created this site because so many of the Macintosh users that I have
encountered have expressed frustration that they don't know what to do,
or what to use, for performing routine maintenance on their Macintosh
running OS X. There is also a huge amount of misinformation going
around on the subject. Even Apple has contributed to the confusion with
conflicting tech notes on their Web site. With the assistance of a few
free utility programs, routine maintenance under OS X is very easy. The
problem for most users is figuring out which utility to use, and for
what. This site will tell you that.
Just a little routine
maintenance can make a Macintosh that is acting old and slow run like
it was new again! It can also banish vexing spinning beachball cursors,
rid you of "out of memory" error messages, and keep your valuable data
from being lost.
The Philosophy behind this site:
is not (necessarily) a site for experts and power-users. What I
recommend here is what I see as the easiest, quickest, surest, least
intimidating, and least expensive way to accomplish valuable routine
maintenance. If you enjoy inputting arcane commands at a UNIX prompt,
if you know UNIX inside and out, if you have money burning a hole in
your pocket for commercial software with lots of questionable features,
or if you enjoy playing around with the features of powerful (and
potentially dangerous) software that you don't really understand, this
site isn't meant for you. I freely admit that there are other ways to
do the routine maintenance suggested on this site, but the procedures
that I recommend here are designed to be the best ones for the average
I've tried to make it easy as possible. I
tell you what you should do, and what you should do it with, and
roughly how often. If you are an average user, you can just follow my
recommendations and be happy that you have done what is necessary. If
you want to know more...the "why," or the other options, or any
controversy that exists in the Macintosh community over the need for
these procedures, I've provided a "Discussion" section for each bit of routine maintenance, as well as a bunch of linked citations.
are several very common myths circulating about Macintosh maintenance.
I don't know anywhere else where they are all acknowledged in one
place. I have endeavored to mention them all on this site. Look for the
headings: "Maintenance Myth".Note:
Many problems that one might experience while running OS X, especially
performance and memory error problems, can be traced to not having
enough RAM (memory) installed. The amount of RAM that comes standard
with a new Macintosh (assuming that you haven't paid to have more RAM
installed at the time of purchase) usually the bare minimum necessary,
and adding more RAM to your Mac is usually a good idea. In my personal
opinion, in no case should a Mac running OS X have less than 512MB of
RAM, for decent performance. OS X 10.5 should probably have at least
1GB of RAM available. More RAM is just about always better.
If you want to find out if you need more RAM, try this free utility:
"Do I Need More Memory?"
(As of the date of this writing, "Do I Need More Memory" is no longer supported by its developer, but it still works perfectly.)
Web page doesn't cover troubleshooting hardware problems. For instance,
many, maybe even most kernel panics (i.e. system crashes)
under OS X, are caused by hardware problems such as bad RAM,
problematic USB hubs, incompatible PCI cards, etc. For more information
on troubleshooting hardware, please have a look at my Jaguar and
Panther troubleshooting Web sites, referenced below.
Disclaimer: When using any Disk Utility,
there is always the slim possibility that things can go horribly wrong.
So, it is always a really good idea to have an up to date backup of all
of your important data before using any Disk Utility.
Actually, its just simply a good idea to always keep a backup of your
data in any case, because hard drives are notorious for failing when
you would least expect them to and you can least afford them to. For
backup software, I suggest that you check out SuperDuper ($28)
and consider getting a FireWire hard drive to backup to. At this time I prefer Other World Computing FireWire hard drives:
you are experiencing a problem with your Macintosh, performing all of
the suggested routine maintenance on this page will often fix the
problem. If it doesn't fix the problem, check out my two OS X
troubleshooting Web sites:
How To Deal With Common OS X 10.2 Jaguar Problems
How To Deal With Common OS X 10.3 Panther Problems
page only refers to Macintosh OS X versions 10.2, 10.3, 10.4, 10.5 and 10.6.
If you have an earlier version of OS X I strongly advise upgrading to a
more recent version, as OS X, in my personal opinion, didn't become a
really good product until version 10.2.
maintenance necessary for OS X 10.2 through 10.6 is almost
identical, but 10.4 through 10.6 can often handle corrupted user
preferences files automatically, and you no longer have to be mindful
of OS X’s built-in maintenance scripts when using OS X 10.5 or later, as they
automatically take care of themselves.
Return to Table Of Contents
Slow operation and generally unusual behavior are signs that may
indicate that permissions need to be repaired on your Macintosh's hard
drive. To do so you can run Repair Disk Permissions from within Disk Utility
, located on your hard drive at: Applications/Utilities/Disk Utility
Note: There is no need to verify permissions before you repair them. Unless you can read the report and understand what Disk Utility proposes to do, there is little point in verifying first.
some reason permissions often seem to get fouled up under OS X 10.2.
Under OS X 10.3 through OS X 10.6, file permissions are less of
a problem. But you should still run Repair Disk Permissions regularly.
Maybe once a month, and every time after you have installed new
software. (Contrary to popular belief, it is not at all necessary
to run Repair Disk Permissions prior to installing new software.
Though doing so won’t hurt anything.)
Open Disk Utility,
and on the left side of the screen select your hard drive, then select
the First Aid tab on the right side and click on "Repair Disk
for further details.
Some users are reporting that they run Repair Permissions over and over
again, and the same permissions are reported as being incorrect, and
they are not being repaired. You should know that, in addition to
reporting faulty permissions, until very recent versions of OS X,
running Repair Permissions in Disk Utility
also gave you advisory messages. For instance, it might report that it
is using an updated set of rules to determine if any permissions needs
to be repaired. These are not error reports and they will not change no
matter how many times you run Repair Permissions. Advisory messages do
not indicate that anything is wrong, and they can safely be ignored.
"We are using special permissions for the file or directory
New permissions are 33261"
As of OS X 10.4.6, Repair Permissions no longer gives these advisory messages.
With OS X 10.5 (Leopard) a number of problems were introduced for some users when
trying to repair permissions. Early versions of Leopard had a
problem whereby running Repair Disk Permissions might take a long time
and you might get a lot of SUID or ACL error messages. For most, but
unfortunately not all, users, this can be remedied by updating to the
latest version of Leopard or updating to Snow Leopard (OS X 10.6). (For those for which updating does not help,
sometimes downloading and running the latest updater again helps.)
About "ACL found but not expected" or “Warning: SUID file” error messages
These messages can safely be ignored.
"Permissions nightmare with Leopard (10.5)”
Some users have noted that their permissions revert to apparently
incorrect settings every time that they restart their Macintosh. Disk Utility/Repair
Disk will correct their permissions, but the next time that they
restart the permissions have been changed again. This has been
traced to the fact that these users are running security software such
as Intego’s Virus Barrier. The security software is intentionally
modifying permissions to close off potential malicious exploits.
Note that in this case, it is neither necessary, or even
desirable, to repeatedly repair your permissions to “fix” this
Maintenance Myth #1: "You need to repair permissions from a copy of Disk Utility that resides on the drive that you are repairing."
This is a myth that is very prevalent.
used to be that you were warned against repairing permissions on one
disk while booted from another because only the receipt files on the
drive you were booted from would be consulted, not the receipt files on
the drive you were repairing, and thus not all permissions would be set
correctly. Though it hasn't been documented by Apple, this is no longer
necessary. As of late in OS X 10.2, you can run Repair Permissions
while booted from a disk other than the one that you are repairing
(e.g. the OS X installer CD-ROM), and it will correctly use the
receipts on the disk being repaired.
From Macintouch (http://www.macintouch.com) on 2/18/06:
Frakes (author of the excellent book Mac OS X Power Tools and a staff
member of Macworld magazine), followed up on "repair permission"
David Marshall wrote, "Those who warn against
repairing permissions on one disk while booted from another seem to be
basing that warning on a mistaken premise...In fact, repairing
permissions uses the receipts from the /Library/Receipts folder on the
volume you're repairing permissions on, not the volume you're repairing
This likely stems from the fact that in older
versions of Mac OS X (pre-Jaguar, I believe), the Repair Permissions
procedure did indeed use the /Library/Receipts folder on the boot
volume, even if you were trying to fix an alternate volume. (This was
even noted in Apple's support documentation. For example, if a
permissions issue prevented you from booting off your normal boot
volume, Apple recommended using the Repair Permissions function while
booted from the Mac OS X Install disc and then, once you were able to
successfully boot from your normal volume, use the procedure again to
ensure the "correct" receipts were used.)
Jaguar (again, as I recall), the procedure was changed -- without much
documentation -- to use /Library/Receipts on the volume being repaired,
boot or not. Unfortunately, many people who had become familiar with
the original procedure never realized it had changed.
See Mark Douma's Disk Utility post in the Apple Discussions User Tips Library for more info.
Myth #2: There are some folks who are very adamant that you never need
to repair permissions under OS X. While repairing permissions isn't a
panacea, they are wrong, it is definitely worth your while to repair
permissions occasionally. The reality is that Repairing Permissions
doesn't require that you purchase anything to do it, it can be
accomplished fairly quickly, it doesn't hurt anything, and after
repairing permissions sometimes the problem(s) that the user is
experiencing are gone. In addition, often the curative effects of
repairing permissions are repeatable and predictable. I don't see any
reason not to do it.
Apple has been clear about the fact
that repairing permissions is sometimes necessary, that you should do
so routinely, and they have provided a tool to do so (Disk Utility/Repair Disk Permissions).
It seems to me that Apple's engineers know best.
Apple offers a list of reasons why you may need to repair permissions
Mac Help (the built-in help system that is part of OS X) tells you that repairing permissions should be done routinely.
Here is a (rather extreme) example of the "it's never ever necessary" school of thought:
Exercises in Futility Part 2: Repairing Permissions is Useless
From the folks at MacFixIt, who recommend routine repair of permissions:
Another follow-up to the Repair Permissions debate
The MacFixIt article makes this excellent point: While Disk Utility's
Repair Permissions feature only repairs permissions for Apple Software
(and not any third party software), much of that Apple software is
system software, and that system software contains routines that are
accessed and used (and used often) by third-party applications. Thus,
incorrectly set permissions, contrary to what some would tell you, can
cause problems with third-party applications.
articles further explain what repairing permissions does, and they
document real-world cases where repairing permissions was extremely
helpful to users.:
Unraveling the Repair Disk Permissions controversy
Repair Permissions Success Stories
More Repair Permissions Success Stories
Dan Frakes has written an excellent article for Macworld on permissions and the need to repair them:
Repairing permissions: What you need to know
Microsoft Office, and especially Microsoft Word, often requires, and responds very well to repairing permissions:
Return to Table Of Contents
1) REPAIR DISK
2) RUN ROUTINE MAINTENANCE SCRIPTS
X runs its own built-in maintenance routines, sometimes called "cron
jobs", or "maintenance scripts", automatically between 3:00 am and 5:30
am each day. (There are daily, weekly and monthly scripts).http://support.apple.com/kb/HT2319
thing is that these scripts do just about nothing of great
importance. If they don't run for weeks, or even months, it's
just not a big deal. So, despite the fact that these are called
"maintenance routines," don't get concerned if they haven't run in a
long time. Don't ignore doing this entirely, though, because in
time failure to run the maintenance scripts will allow your Mac's hard
drive to fill up with a bunch of invisible log files.
You can find a rundown of what the built-in maintenance routines do at:http://arstechnica.com/civis/viewtopic.php?f=19&t=454874http://discussions.apple.com/message.jspa?messageID=8906776#8906776
to OS X 10.5, if you didn't leave your computer on 24 hours a day, or
if you left it on but you let it go into sleep mode at night, these
routines weren't run. As of OS X 10.5 and later your Mac
will run its maintenance scripts automatically at
the next available opportunity if you put your Mac into sleep mode all
night. Though the scripts still won't run if you shut your Macintosh down at night.http://discussions.apple.com/message.jspa?messageID=6552347http://discussions.apple.com/thread.jspa?threadID=2143195&tstart=0http://developer.apple.com/macosx/launchd.html
NOTE: As of OS X 10.5 the maintenance scritps are no
longer handled by the UNIX facility "cron", they are now handled by a
similar facility called "launchd," if that means anything to you.
you are running OS X 10.2 you should probably run all the maintenance
scripts manually every month or two if you shut your Mac down at night.
You can run these routines manually, whenever your want, with the free utility MacJanitor
is not compaitlble with OS X 10.5 and beyond. For OS X 10.5 and beyond,
if you decide that you want to run the maintenance scrips manually, you
can instead use this free utility:Maintidgethttp://www.giantmike.com/widgets/Maintidget.html
If you are running OS X 10.3 to OS X 10.6, the easiest thing to do is to download and install the free utility PseudoAnacron
which will make sure that your routine maintenance scripts run every time that you startup your Macintosh:http://www.jaw.it/pages/en/x_misc.html
NOTE: On PseudoAnacron
's Web site it says that it works with OS X 10.4 to OS X 10.5. I've been in touch with PseudoAnacron
's developer, and he says that it works perfectly with OS X 10.6 also. There is an earlier version of PseudoAnacron
available for OS X 10.3.Discussion.
you want to be sure that the built-in maintenance tasks have been run,
the daily, weekly and monthly maintenance scripts each write the
details of every run into their own log file, which you can check. Open
application (located at: Applications/Utilities/Console), go to:
File --> Open Quickly --> /var/logs/. Select "daily.out", "weekly.out" or "monthly.out" for the maintenance logs.
Return to Table Of Contents
3) CLEAR CACHES
though running the routine maintenance scripts clears out some
temporary files, none of the system caches are touched by them.
Occasionally caches become corrupted, impacting the performance and
stability of your Mac. So it is a good idea to every rare now and
then use a utility that clears the system caches, and/or your Internet
browser caches. Deleting caches won't hurt anything. However, over time
a cache speeds up your computer (assuming that you do some things
repetitively), so if you aren't experiencing any problems, you may want
to leave your caches alone. On the other hand, if it has been ages
since you have flushed your caches, or if your computer is running
slowly, or if you are experiencing odd problems, it might be a good
idea to flush them. Use your discretion.
Cache Out X is a free program
which cleans out system and Internet browser caches. This can prevent
some very hard to diagnose flaky behavior. (You may not want to
regularly clear your browser cache if you have a slow speed connection
to the Internet. Until your browser cache is rebuilt, your access
to favorite sites may be very slow.) You can get Cache Out X from:
According to MacAddict, October 2005, page 20, it is a good
idea to occasionally clear out application-specific caches. They
specifically recommend clearing out the two main cache folders in Mac
1) /Library/Caches, and 2)~/Library/Caches. ("~"
stands for the folder with your username on it in your Users folder.)
While Apple doesn't recommend doing this routinely, they indicate that
it is a good idea in certain situations:
A MacOSXHints tip also suggests clearing out the application cache files occasionally:
This hint notes that there may be quite a few extraneous cache files in your ~/Library/Caches folder.
You get to the ~/Library/Caches folder by following the path:
[hard drive] --> Users --> [your user name] --> Library --> Caches.
You get to the /Library/Caches folder by following this path:
[hard drive] --> Library --> Caches
should be able to delete everything safely. However, if you want to be
extra careful, just create a new folder on your desktop, and drag
everything from your Caches folder into it and restart. You can trash
the folder on your desktop when you are certain that everything is
Return to Table Of Contents
4) REPAIR AND BACK UP PREFERENCES
become corrupted way too often under OS X 10.2. This is still a problem
under OS X 10.3, but much less of a problem under OS X 10.4 and later.
If an application or applications quits unexpectedly under OS X, the
first thing to suspect is that you have one or more corrupted user
is a free utility that will check for corrupted preferences files. (It
will sometimes even locate preferences files that are corrupted before
you start experiencing any problems from them, so it is a good idea to
use Preferential Treatment regularly. About once a week.) Preferential Treatment
allows you to delete any corrupted preferences files from right within
the program, so that they will be rebuilt when you restart the effected
all of your preferences files are known
to be in good shape, it is a good idea to back them up. That way,
in the future if you have a problem with a corrupted preferences file,
you can replace the corrupted file instantly with a clean copy. This
also allows you to avoid having to re-set any application or system
preferences settings. You can use a backup program for this, or
you can copy your entire Preferences folder manually. You can
find your user Preferences folder at:
You get to the ~/Library/Caches folder by following the path:
[hard drive] --> Users --> [your user name] --> Library --> Preferences
a copy of the user Preferences folder by holding down the Option key
and click-dragging the folder to your desktop. This will leave
the original in place and make a copy on your desktop. Click on
the copy on your desktop once to select it, and choose File -->
Create Archive. This will compress the folder, making it inactive
(so your Mac's system doesn't get confused by having a duplicate
Preferences folder for any reason) and stash the duplicate folder
somewhere where you can find it if you ever need it. (Do NOT keep
the duplicate anywhere in the Library folder.)
the event of corruption of either individual preferences, or the entire
folder, you can simply substitute the backed-up preference file, or the entire backed-up Preferences folder for the existing
one. This eliminates the need to troubleshoot your
user preferences if you suspect that one of your preferences files is
If an application unexpectedly quits under OS X
10.4 or later, you are given the option of restarting that
application with its ".plist" (preferences) file(s) deactivated, to see
if that was the problem, and if it was, a new ".plist" is substituted
for the old one. This approach isn't as pro-active as using Preferential Treatment routinely, but it should be entirely adequate and effective.
Tiger's new and improved “application crash” dialogs
Preferences Files: The Complete Story (Part V); How .plist files become corrupt and troubleshooting the results
Return to Table Of Contents
5) DO A FILE SYSTEM CHECK AND REPAIR DISK
recommend that you occasionally restart your Mac, and hold down the
Shift key right after the startup chime is played, and keep it held
down until the spinning black bar cursor appears. There is
no need to hold down the Shift key past the time that the
spinning bar cursor appears.http://support.apple.com/kb/HT1455?viewlocale=en_US
This procedure invokes what Apple calls a "Safe Boot":
and your Mac will report that it has been booted (started up) into Safe
Boot mode. During startup in Safe Boot mode your Mac will do a file
system check, entirely in the background, with no working status
indicated, or report generated, and any problems will automatically be
It may take a while for your Mac to start up in Safe Boot mode. Be
Patient. Once it has fully started up, you should immediately
restart your Mac normally, because certain files are deactivated when
you startup in Safe Boot mode.
Note: A wireless or Bluetooth
keyboard and mouse may not allow you to startup in Safe Boot mode.
(Also, be sure that all of the latest updates for your computer
you may prefer to check your hard drive, and repair any problems, by
using the method outlined below. The advantage of using the method
outlined below is that both a working status indicator, and a report,
are generated. The disadvantage is that you will have to have, and
start up from, your OS X Installer CD-ROM.
Put your OS X
Installer CD-ROM (or DVD) into your optical drive (if you have multiple
installer disks, use the first one), and startup from it (by holding
down the "C" key during startup or restart). From there you can choose Disk Utility
from the Installer menu. Click on the disk that you want to repair in
the left column and then choose the First Aid tab, and then click on
Repair Disk. (If the Repair Disk button is gray, you either didn't
click on the correct item in the left column, or you aren't started up
from the Installer CD-ROM. You can't repair the disk that you have
started up from.)
Macintosh users know that under OS 8 and OS 9, if you were experiencing
nasty problems with your hard drive, that running Apple's Disk First Aid usually didn't fix them. In such cases, users often resorted to using the commercial product Disk Warrior,
which could perform near miraculous feats of repair on your hard drive.
It was also an invaluable tool for routine preventative maintenance.
Under OS X, Disk Utility/Repair Disk is the replacement for Disk First Aid. So, the question most folks have is, 'is Disk Utility/Repair Disk as lame as Disk First Aid, and is Disk Warrior still an invaluable utility to have?' There is an interesting thread on TidBits Talk that covers this topic:
Looking for Disk Warrior Justification
The answer is that Disk Warrior
is a marvelous tool...when you need it. Fortunately, under OS X you
don't need it as often as you needed it under previous versions of the
Mac OS. For instance, you don't need to run Disk Warrior
routinely as a preventative measure. (Though doing so, if you already
own Disk Warrior, isn't a bad idea.) OS X is plenty stable without
having to constantly rebuild its directory. And so, in my opinion,
there is no need to purchase Disk Warrior (for about $100) unless a
situation arises where Disk Utility/Repair
Disk reports that it can't repair a problem with your hard drive. This
is not to demean Disk Warrior. When you do need Disk Warrior, because
your disk directory has developed errors that Disk Utility can't fix, it is a godsend to have.
For further information about disk repair software, have a look at:
with a follow-up on TechTool Pro at:
are other ways to run a file system check/Repair Disk under OS X, such
as by booting into Single User Mode, or by running the command "fsck"
from the Terminal, but these are more advanced ways to do exactly the
same thing, that I don't think that the average user needs to know
Return to Table Of Contents
For more information than you need, see:
6) DEFRAGMENT A HARD DRIVE THAT IS LOW ON CONTIGUOUS FREE SPACE
Macintosh Myth #3
: Most folks with an opinion will probably tell you
that Mac's running OS X never need to have their hard drives
Here is a quote from a MicroMat technician, that I think is very insightful:
The claim that installations of Mac OS X on HFS+ volumes do not
fragment is a myth believed by people who do not have disk optimizers
that allow them to see how much fragmentation their disks have. It is
an example of ignorance that is not able to be removed by any amount of
evidence. I think theologians call that "invincible ignorance". It is
now a widespread form of the pollution of information space.
Macs running OS X can benefit quite a bit from defragmenting their
hard drive. But not for the reason that you might expect There is often
little in the way of performance to be gained by defragmenting your
hard drive. But defragmenting your drive can stave off some very flaky
behavior, out of memory errors, and possibly even data loss.
X handles "file" fragmentation (a file being broken up into chunks and
strewn across your hard disk) automatically, and fairly well, every
time that you launch a fragmented file under 20MB.
(registration required to access)
But OS X doesn't handle "drive" fragmentation (small bits of free space
between files) well at all. In fact, OS X is prone to huge amounts of
Drive (as opposed to file)
fragmentation under OS X is mostly irrelevant with respect to
performance, as long as it isn't severe. Where hard drive fragmentation
becomes important is when there are no longer any large contiguous
chunks of free space left on your drive for OS X to use for working
space, for virtual memory, temp files, databases, etc. When this
happens, OS X can start acting flaky, and eventually, in extreme cases,
it will suffer from data loss.
used to recommend that folks defragment their hard drive when it was
approaching 80% full (no matter how large the drive is), because I've
heard from so many folks who were experiencing out-of-memory errors and
flaky behavior at this level (no matter how large their drive was), and
defragmenting invariably fixes the problem. But I've heard from a number
of users who made heavy use of their drive, and they have experienced
the problem as early as around 60% full. And other folks won't
experience the problem until their drive is well over 80% full. Clearly
how you use your drive makes a difference as to when, or if you run out
of free contiguous space on your hard drive.
instead of using a rough rule of thumb on when you should consider
defragmenting your hard drive, what I recommend is that folks check to
see how much free contiguous space the is on their drive routinely,
once their drive is over 50% full. You can do this quickly and easily
with the free demo version of iDefrag:
or the free utility ShowVolumeFragmentation
There is no need to purchase anything until and unless you need to.
When you have no large chunks of free contiguous space left, you can
expect problems to begin to appear if you don't defragment your drive.
Note that if you let this problem advance too far, it may become for
any utility to work on your drive, protesting that there isn't enough
free space on your drive for it to be able to run. (This despite the
fact that you may have many gigabytes of "total" free space left on
You may never need to defragment your drive
(prior to purchasing a new one because the old one is becoming too full)
or you may need to do so much earlier than you would expect, but by
checking with one of these free tools you won't have to guess whether
it is necessary or not.
If you drive needs to be defragmented, the "only" hard drive defragmentation utility that I recommend is iDefrag. (See my comments about other hard drive defragmentation utilities in Note 1.
below) It is the only one that I know of that can optimize the files on
your hard drive in a totally OS X-savvy way. OS X, under OS 10.4 and
10.5, has a journal, a hot band, virtual memory, metadata, etc. to keep
track of. It is very important that these things be located properly on
the disk or performance will be compromised.
Technical data about the hot band and meta data on hard drives running OS X 10.4 and later:
is the only hard drive optimization tool that does this perfectly
(despite what some of the other companies that make hard drive
defragmentation tools say).
The downside to iDefrag
is that you can't do a comprehensive defrag without booting from a
volume other than the one that you are defragmenting. Coriolis Systems
offers free software to allow you to make a boot CD-ROM to run iDefrag from.
option, instead of defragmenting your hard drive with a software
utility program, is to simply purchase a new, bigger hard drive; copy
all of the data on the old drive to the new drive, and then
reinitialize (i.e. wipe clean) the old drive and start over with it.
Moving all of your data from one drive to another will automatically
defragment your data. Though it won't optimize it.
have to reinitialize your data on the old drive for this plan to work,
because if you just move "some" data from your old drive to your new
drive, the old drive will still be badly fragmented, and without
defragmenting the old drive it will still probably be flaky. (That is,
even if you free up some space on the old drive, there more than likely
still won't be the large chunk of contiguous free space available that
the OS likes to run properly.)
Defragmenting your hard
drive prevents any unusual behavior from your OS because it creates
contiguous space, combining fragments of space strewn all over your
drive into one large chunk of space.
Note that clearing
off data from your drive, even a large amount of data, without also
defragmenting, may not create enough "contiguous" space to keep your
Mac running well.
Definition of Terms:
Types of fragmentation:
1) "File fragmentation, where file are broken up and are not contiguous
2) "Drive" fragmentation, where, though files may be contiguous, the free space on the drive is fragmented.
means that things (that is, data, e.g. files and applications, and free
space) are made contiguous (that is, not broken up into small bits and
strewn about at different places) on your hard drive.
means that not only is the drive defragmented, but data is put where it
should be and.or is put where it will provide optimum performance.
Let's refer to files A, B, C and D, and free space "__".
is a drive with no file fragmentation. All the files are contiguous,
but free space is fragmented. In other words, there is no file
fragmentation but there is disk fragmentation:
Here is a drive with both the files and free space fragmented:
is a drive with no file or free space (disk) fragmentation. All of the
files are contiguous, and all of the free space is contiguous:
take a look at that first example, where there is a lot of disk
fragmentation even all of the files are contiguous. Have you ever run a
Mac under OS X with too little RAM? It was a dog, wasn't it? That's
because your Mac was hitting your disk in a big way, using virtual
memory instead of RAM for tasks. Now, think of the effect that you
might see if you forced your Mac to use hundreds of little spaces all
over your drive to write virtual memory to, instead of having it
written to one big contiguous space. That's why drive fragmentation is
more important than file fragmentation.
OS X automatically defragments files. OS X doesn't do any drive defragmentation at all.
that if you actually defragment your hard drive as part of a routine
maintenance program (rather than just keep track of how much free
contiguous space is available), let's say every coupe of months, then
it won't take long to defragment your drive each time, and any
potential problem will never rear its head. In addition, you should be
able to use close to every last gigabyte of space on your hard drive,
and you will always have every last ounce of performance that your Mac
can give you as as side benefit.
See Note #1 below for more information on file defragmentation.
Return to Table Of Contents
7) CHECK S.M.A.R.T. STATUS
drives are quite a bit more reliable these days than they were just a
few years ago. Unfortunately, the old saying that "all hard drives die
eventually" is still true. It would be nice to know in advance when a
hard drive is going to fail. That way you would have time to backup
your data before your drive ultimately met its end. S.M.A.R.T.
(Self-Monitoring Analysis and Reporting Technology) is a feature built
into most modern hard-drives that acts as an "early warning system" for
pending drive problems. OS X 10.3 and above have this ability built-in,
but it only works if the actual hard drive in your Mac has this
technology built-in also. Disk Utility
which comes with OS X (it is in your Application/Utilities folder),
under OS X 10.3 and above can tell you the S.M.A.R.T.-status of your
hard-drive. Unfortunately, you have to remember to regularly launch Disk Utility
to check this. (See below for free utilities that will automate this process.)
To check your drive's S.M.A.R.T.-status using Disk Utility, launch Disk Utility
and select your hard drive. If at the bottom of the window it says
"Verified," your drive is in good shape. If it says: "About To Fail"
you need to:
1) Not shut down your computer and hard drive until you have done the following...
2) Back up your hard drive, which you should do immediately, if you haven't already done so.
Hard drives on their last legs often will finally fail by refusing to start up.
I've been told that there is no hope for an internal drive once it
reports "Failing" as its S.M.A.R.T status. Its time to get a new drive.
is a free application that can automatically warn you of hard-drive
failures before they actually happen! It does so by periodically
polling the S.M.A.R.T.-status of your hard-drives.
is a free utility that reads mounted disks' S.M.A.R.T. status and
reports it. You add it to your Mac's login items to have it run
Volitans' SMART Utility ($20 for a 10 copy license) is different from other similar utilities which only read the overall S.M.A.R.T. Status. SMART Utility
goes farther and displays the individual attributes tracked by
S.M.A.R.T in an easy to read format so that you can see their status
and information, and it also uses its own internal algorithm based on
those attributes to detect drives failing before S.M.A.R.T. normally
would. This pre-fail detection can save your data well before
S.M.A.R.T. has determined that the drive is failing.
Note: FireWire and USB hard drives (that is, external hard drives),
even if their internal mechanism is S.M.A.R.T.-enabled, can't be
checked for S.M.A.R.T. status.
There was a study released by Google:
Return to Table Of Contents
Failure Trends in a Large Disk Drive Population, which concluded that S.M.A.R.T. wasn't a reliable predictor of drive failure.
More information on S.M.A.R.T. technology:
8) CLEAR YOUR DESKTOP
Moving things to a location other than on your desktop is an easy and
free way to pick up better performance. Users have noticed that
reducing the number of items on their Mac’s
desktop can noticeably increase the performance of certain activities
in OS X. This is easy to do. You can even create one folder on your
desktop and put everything on your desktop in it. That will do the
trick. Nested items within folders on the Desktop don't count. It is
only the total number of items directly on your desktop that matter.
way to go is to put all of the items that would normally reside on your
desktop, that you want to be able to access quickly, in a folder; park
that folder somewhere other than on your desktop, and then drag that
folder to your Dock so that it is always available from the Dock.
Whenever you click and hold (or Control-click, or right-click on a two
button mouse) on that folder in the Dock, you will be presented with a
menu of everything in that folder to choose from. Sort of like the old
classic Apple Menu.
Under OS X 10.5 this problem is ameliorated
because your Mac’s desktop is no longer the default location for new
downloads. There is a separate Downloads folder in your Dock.
that you put on your desktop don't really reside there. They actually
reside in a folder in your user account. The Desktop folder can be found at:
[hard drive icon]/Users/[your user name]/Desktop
otherwise known as: ~/Desktop, or your user desktop folder.
Open this folder and you will find everything that you see on your desktop!
would be logical to conclude that the things represented on your
desktop use a good chunk of cached memory and/or that it is CPU
intensive to draw the icons for the things that reside on your desktop.
And to a certain extent this is true, because under OS X each icon on
your desktop is more like a folder than an ordinary icon.
However, I’m told that another source of the slowdown from
keeping an excessive number of items on the Desktop is due to the
“windowserver” process generating a huge number of logfiles, which
draws resources away from other system tasks.
Return to Table Of Contents
9) RESET SAFARI
Lots of folks have problems with Safari bogging down and/or exhibiting
the spinning beachball. When this starts to be a problem, there are
several things that you can do to fix this.
This hint from MacFixIt, http://www.macfixit.com/, works really well for some:
"… go to /(username)/Library/Safari folder and delete the Icons folder."
This will clear cached favicons (little icons that appear in the address bar).
This tip from Mac OS X Hints will keep this folder from filling up with favicons again:
Mac OS X 10.3.x and Mac OS X 10.4.x there exists and issue where some
users experience a stall in Safari or other Web browsers when accessing
certain Web sites that usually leads to a complete system freeze
accompanied by the unending "spinning beach ball" process indicator.
One solution to this problem is the free utility Unlockupd:
rather extreme, but simple and usually quite effective thing to do is
to restore Safari to like-new performance is to reset Safari, which
will clear Safari's cache and other gunk:
Choose "Reset Safari" from the Safari menu and click "Reset".
Resetting Safari clears the history, empties the cache, clears the
Downloads window and removes all cookies. It also removes any saved
user names and passwords or other AutoFill data and clears Google
search entries. I'm also told that resetting Safari alters your
keychain and bookmarks. For this reason you may want to make copies of
so that those can be restored after resetting Safari.
of Safari 3.0 the "Reset Safari" command has been substantially
improved, now offering users the option to customize the "reset", and
"delete only select items". It also now has the capability to remove
all Web site icons ("favicons"), which can have a surprisingly dramatic
performance boosting effect for Safari.
There are lots of great hints for Safari maintenance here:
Safari performance tips from MacFixIt:
Safari performance tips from MacRumors:
Return to Table Of Contents
10) REBUILD SPOTLIGHT'S DATABASE
Sometimes, under OS X 10.4, your Macintosh will slow to a crawl, and
you can hear that there is a lot of hard drive activity, even though
you aren't doing anything disk-intensive with your Mac. To determine
what's running in the background, start up Activity Monitor (in
Applications/Utilities folder), set it to show "All Processes" and sort
by down-arrow "% CPU". That'll show which processes are running, and
which, if any, are hogging CPU cycles to the point of drastically
slowing down your Macintosh. Look for Dashboard widgets that are
hogging CPU cycles. Poorly coded widgets have been known to hog CPU
cycles even when you would expect them to be inactive. Uninstall any
CPU hogging widgets.
If the culprit is something named "mds" or "mdimport" (the
processes that handle Spotlight data), it could signal corruption of
your Spotlight database. (Make sure that you aren't just seeing normal
Spotlight indexing. See if this problem perseveres after your computer
has been left on all day.) If this problem persists, you can easily
rebuild your Spotlight database by opening System Preferences, choose
the Spotlight panel, click on the Privacy tab, and drag your main
drive's icon into the Privacy window. Now highlight your hard drive's
icon within the Privacy window and
click on the "-" button (that is, the minus button in the Privacy Window).
you could highlight the hard drive icon in the Privacy window and hit
the delete key. This will cause the Spotlight database to be deleted
and automatically rebuilt. (You won't be able to use Spotlight while
its database is being rebuilt.).
After doing this, leave
your Mac on for an entire day (making sure to set the Energy Saver
System Preferences so that your Mac won’t go to sleep) and allow
Spotlight to index your entire drive uninterrupted.
have suggested that it might be a good idea to rebuild your Spotlight
database after every time that you update to a new version of OS X (a
full "point" release, e.g. 10.3 to 10.4) .
Return to Table Of Contents
11) REBUILD MAIL’S DATABASE AND BACK UP YOUR EMAIL
As of OS X 10.4, all archived messages in Apple’s Mail program are kept
in individual Finder-readable files. There are no archived messages in
Mail's database. OS X keeps your archived mail messages in this
This is a good thing. Some other e-mail programs, notably
Microsoft’s Entourage, store all of your messages in one big monolithic
database. If the database in a program with a monolithic database
becomes corrupted and unrepairable, you can lose all of your archived
However, Mail’s performance can lag, and it can become less stable, as you store more and more archived messages in it:
deleting old, unwanted e-mail messages, and rebuilding Mail’s database,
will usually give Mail a very noticeable performance boost, and help
ensure continued trouble-free operation.
Since there are no
archived e-mail messages stored in Mail’s database, it is quite safe to
rebuild Mail’s database, because if something goes wrong with the
rebuild, you can just start over, having lost nothing.
now and then (or, ideally, routinely as you use Mail) you should go
through all of your mailboxes in Mail and delete all of the messages
you no longer wish to keep. Then, in Mail, choose:
Mailbox menu --> Erase Deleted Messages --> In All Accounts to purge all deleted messages.
After doing this, quit Mail.
You can then use this free utility to quickly and easily rebuild Mail's database:
SpeedMail (free, donations accepted)
Or, instead, you can use this program, which has the advantage that you can set it to run automatically on a schedule:
many folks, storing their old e-mail messages, and being able to search
through them, is very important. Unfortunately, if you use Mail
itself to store huge amounts of archived e-mail, eventually doing so
will impact both Mail's performance and stability. There are a
number of automated backup/archive utilities for Mail, listed on the
following Web site, that will allow you to both backup and search
through archived mail outside of Mail itself:
I've been asked if just backing up all the folders in:
a sufficient job of backing up one's e-mail. I've heard from a
number of users who have had to restore their e-mail from backups of
this type, and they have reported problems getting Mail to integrate
and recognize individual messages when they have had to restore them
from such a backup. Most of the application-specific Mail backup
programs claim to instantly do that for you. Which sounds like a nice
feature to have. (Of course, as of OS X 10.5, you can just use
Time Machine to back up and access archived e-mail messages.)
For background on what SpeedMail does, see:
Return to Table Of Contents
Note #1) More On Defragmenting Your Hard Drive
I indicated above, there are those who will tell you that you *never*
need to defragment your hard drive, and to some extent they are
correct. Certainly the average user, with a hard drive that isn't
anywhere close to being full, and using applications that don't require
every last bit of performance that can be mustered, won't notice any
significant performance gain, or other benefit, from defragmenting
their hard drive. (Though you may find defragmenting your hard drive to
be important if you do disk-intensive work, such as video editing.)
Just about all of the experts agree that there is a Macintosh
problem that manifests itself when your Macintosh gets somewhere around
80% full. However, not all of these experts seem to realize that the
problem is due to a lack of free contiguous space on your hard drive.
As a result, these folks usually advise that you deal with this whole
problem by purchasing a new drive when your old drive gets to be about
80% full. That will work, but, personally, when I have a 200GB drive,
with 40GB unused, I expect to be able to use that 40GB before I have to
buy a new drive. 40GB is a huge amount of space and it seems silly to
just give up on it. Frankly, it seems to me that advising that one
always keep a ridiculously large amount of free space available on
their drive, to assure reliable operation, isn't the best course.
See under: "Make sure you have enough free space on your startup volume"
Realistically, 20 percent of your Mac OS X startup volume should be
kept clear in order to achieve best performance and avoid disk problems.
Rob Griffiths, of MacOSXHints.com and Macworld magazine writes:
Keeping at least 10% of your drive space free is advice that I've
followed for quite a few years; I don't know if that figure is too high
or too low, but I've never run into any drive-space-related issues
using it as a benchmark.
Joe Kissell of Macworld magazine recommends defragmenting your hard drive as it starts becoming too full or when there is severe disk fragmentation.
Macworld, February 2008, page 102.
a UNIX system employs non VM for memory management (that is, real
memory) the issue of swapping is a different beast altogether. This is
because when swapping memory out it has to be done in large contiguous
chunks (not small pages of 4096 bytes). For this reason it's important
that the swap file space on disk be a contiguous set of
tracks/cylinders and if possible have a separate data path to avoid
interfering with other user i/o activities.http://www.macosxhints.com/article.php?story=20010613140025184
Apple says that you generally don't need to defragment your hard drive if you are running OS X 10.2 or higher:
But then they say: If your disks are almost full, and you often modify
or create large files (such as editing video...), there's a chance the
disks could be fragmented. In this case, you might benefit from
defragmentation, which can be performed with some third-party disk
Here they say that in some instances defragmenting your hard drive may be necessary:
So, Apple seems to be saying that you don’t need to defragment your
hard drive...except in those instances where you need to defragment
your hard drive.
adheres to the "leave a ridiculously large amount of free space on your
drive and then replace your drive when it prematurely begins to hit its
head" concept. They admit that defragmenting your hard drive is a good
idea, but they will only admit it for those who badly need to do it.
(Folks who really give their drives a workout, and those who edit
video.) For everyone else they feel that its just fine for them to
purchase a new hard drive when they encounter a problem with a lack of
free contiguous drive space. As Apple says, modern hard drives are big.
Apple knows that for many users it will take a long time for them to
fill their drive up to around 80% full, if ever. They aren't about to
recommend maintenance that isn't necessary for everyone. In addition,
Apple has always been reluctant to admit to users that they might not
be able to get along without some third party utility. For instance,
under OS 8 and OS 9 Disk Warrior was practically a necessity. But you never heard Apple admit this.
to one of their technicians, MicroMat feels that under certain
circumstances that defragmenting your hard drive is very important, and
may be even be critical to preventing data loss, and based on my
experience I concur:
Continuation of discussion on fragmentation by MicroMat tech:
MacFixIt has an article on defragmenting your hard drive, including a test of iDefrag:
“...in our informal testing, we noticed significantly snappier
operation of Spotlight and quicker response from Mail.app after
performing only the least invasive of iDefrag's optimization routines.”
“The bottom line is that users with large files will benefit most
greatly from defragmentation routines in Mac OS X. However, use of the
disk optimization routines offered by tools like iDefrag can also serve as a boon to casual users of Mac OS X looking for a speed boost.”
Other Defragmentation Utilities...and Disk Warrior:
manufacturers use the terms "defragmentation" and "optimization"
interchangeably. For instance, as far as I can tell, MicroMat does this
even though TechTool Pro doesn't really do any optimization when defragmenting your hard drive.
Prosoft's Drive Genius
does both file and disk defragmentation, but as far as I can tell, no
optimization. However, their advertising seems to use the terms
"defragmentation" and "optimization" interchangeably.
Intech Speed Tool's documentation:
http://www.speedtools.com/Users Guides/Disk Defrag Guide.pdf
says that the product defragments your drive, but it does not optimize
it. So it would appear that Intech's product is not an optimal choice.
NOTE: Alsoft refers to what Disk Warrior,
their popular hard drive repair utility, does as "optimization" and/or
"defragmentation." However, they are referring to the drive's
directory, not to defragmentation and optimization of the drive’s files
(data) and free space on the drive. Many folks get confused by the
terminology used and think that Disk Warrior is a hard drive
defragmentation utility, and it is not. Your Macintosh maintains a
"directory" which is an invisible structure that is a catalog of all of
your Mac's files and system parts. (It is actually more complex than
this simple explanation.) If the directory becomes corrupted your Mac
can lose track of what is on your hard drive. (e.g. Your files
For a more detailed and technical explanation, see:
fixes your Mac's directory by rebuilding a new optimal one from
scratch. Other utilities attempt to fix the directory by patching the
directory structure rather than by rebuilding it. Disk Warrior also optimizes the structure of the directory for maximum overall disk performance.
Alsoft's hard drive defragmentation product, PlusOptimizer,
is many years out of date, and it runs in OS 9 only. I highly recommend
against using this product at this point (assuming that you even can),
as it is not OS X-savvy and its use may seriously degrade your hard
Return to Table Of Contents
Note #2) Routine Maintenance Or Troubleshooting Technique
A couple of well-known Macintosh authors have recently said that many
of the procedures listed on this Web page, such as Repairing
Permissions, are not what they consider to be routine maintenance, but
rather they are best reserved to be used as troubleshooting techniques
when your Macintosh shows signs of decreased performance or starts
acting in an unusual manner. They say that you can go a long time
without having to perform any of the procedures that I list here.
can’t say that they are wrong. However, I compare it to checking
and adjusting the air in the tires of your car. Do you do that
regularly, or do you wait until your tires start to show signs of
unusual wear and/or your car starts to handle poorly? Many people
do the latter, and I can’t say that they are wrong in doing so.
if it took less than ten minutes to check and adjust the air in your
car’s tires, and you didn’t have to get your hands dirty, or leave the
comfort of your home to do so? Would you then be more likely to
check the air in your tires regularly, especially considering the
benefits of better handling, longer tire life, etc.? It seems to
me that it would be well worth your while to do so.
where my feelings are as far as the procedures on this Web page.
You can do them all quickly (see below), easily, and at no
monetary cost, and there is no downside to doing them. But the
upside to doing routine maintenance is that your Macintosh will always
be running at its best (not just when you have noticed that things are
really out of wack, and you decide that its time to troubleshoot and
repair them), and you may even avoid some nasty problems down the road.
You can decide for yourself if the extremely modest investment of time
and effort is worthwhile to you.
Return to Table Of Contents
Routine Maintenance In Under 10 Minutes!
so there’s been a lot of information to digest on this Web page.
By now you may be thinking that all of these maintenance tasks
will take way too long to do routinely, and that there are too many
utilities to keep track of to do it all. Well, fortunately, that
doesn’t have to be the case. First, not all of the above eleven tasks
have to be done frequently, and some can be set to be performed
automatically. Also, there are what is known as “multi-function”
utilities that can do most of what needs to be done all in one program,
to make things faster and easier. The one that I recommend is
YASU (Yet Another Software Utility), which is free (a donation is
requested) from Jim Mitchell.
Here is what you need to get for
performing routine maintenance in under 10 minutes:
iDefrag (demo version)
all three in your Utilities folder (located inside of your Applications
folder). Drag the icons for these three utilities, one at a time, to
your Dock so that they are always easy to get to.
and, if you are using a version of OS X prior to 10.5, download Anacron
and install all three according to their included instructions.
Here are 5 steps for performing all of the necessary routine maintenance in under 10 minutes.
1) Launch YASU and make sure the following are UNchecked:
Make sure that everything else in YASU
’s main window is checked.
Choose: Restart After Done.
Click on Start.
2) When your Mac restarts after YASU
is done, immediately after the startup sound, hold down the Shift key
until you see the spinning pinwheel. Let go of the shift key and
wait for your Mac to start up fully. (Which might take noticeably
longer than usual.) Once your Mac is fully started up, choose
Restart in the Apple menu and allow your Mac to restart again normally.
(This time don’t hold down the Shift key.)
3) Run Preferential Treatment.
4) Run iDefrag, or the demo of iDefrag,
have a look at the chart showing the data on your drive, and check to
see that there is at least one large chunk of contiguous free space (in
white) left on your hard drive.
5) Launch Mail, and erase all deleted messages in Mail.
Mailbox menu --> Erase Deleted Messages --> In All Accounts
Then quit Mail.
your desktop clean is an ongoing task. You only need to reset
Safari or Spotlight when they need it. Rebuilding Mail’s
database, the built-in maintenance tasks, and monitoring of your hard
drive’s S.M.A.R.T. status will be handled automatically.
Return to Table Of Contents
Software mentioned on this site, and where to get it.
"DO I NEED MORE MEMORY?"
CACHE OUT X
ANACRON for Tiger (OS X 10.4)
ANACRON for OS X 10.2 and 10.3
Free multi-function utilities:
Ordinary users might find some of the options included in typical
multi-function utilities confusing and/or intimidating. Even worse,
they might find some of them to be dangerous! The following
multi-function utility is easy to use and unlikely to get anyone in
trouble. A multi-function utility will often save you time when doing
routine maintenance, however, if you are intimidated by all of the
features in the following multi-function utility, it might be best to
stick with single-function utilities.
There is no need to write and tell me about the dozen or so other
multi-function utilities for OS X that are available. I've left out
mention of them on purpose for the above reason.)
YASU (Donation requested.)
can take the place of several of the above recommend utilities. YASU
runs the cron jobs, clears caches, repairs permissions, and more. I
recommend YASU because it doesn’t get ordinary users in trouble by
providing dangerous features, it is free (a donation is requested by
its developer), and it is quick and easy to use. On the negative side,
it doesn't give an estimate for the time it will take to complete a
task, and it doesn't give you a log of errors found and repairs done.
MACARONI ($9) (runs maintenance tasks automatically on a regular schedule)
DISK WARRIOR (Highly recommended if you have hard drive problems that Disk Utility/Repair Disk can’t repair.)
iDEFRAG (Highly recommended for defragmenting your hard drive.)
Return to Table Of Contents
The following are not sponsors, but rather products that I recommend highly.
If you have any additions to this Web site to suggest
I would very much appreciate hearing your suggestions.
Send them to:
Randy B. Singer
I'd like to give special thanks to Charles Lindauer for helping me with this site.
is a wiz with Dreamweaver. If you would like to hire a web
designer/developer, or if you need a Macintosh consultant in the North
San Fransciso Bay Area, e-mail me and I will get you in touch with him.
About The Author Of This Web Site
Randy B. Singer is:
- The head of the MacAttorney User Group
with, at this writing, well over 8,000 members!;
- A co-author of The Macintosh Bible (4th, 5th and 6th editions);
- Author of the ABA publication:
The Macintosh Software Guide for the Law Office
If you are a Macintosh-using attorney or legal professional (including law students)
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