Mac Maintenance, Repair and Optimization

Avoid data recovery, stop your mac from freezing and getting the spiny pinwheel. Make your Mac run faster than when you got it! I tested many of the common troubleshooting techniques to find out how much faster they make your computer.


  1. Update anything/everything.
  2. Repair your permissions.
  3. Restart your computer.
  4. Repair your disk.
  5. Run DiskWarrior.
  6. Run TechTool Pro.
  7. Zap your PRAM/NVRAM.
  8. Empty suspicious caches.


  1. Optimize with Onyx.
  2. Run your crontabs.
  3. Update your prebindings.
  4. Run DiskWarrior.
  5. Defragment your hard drive/partition.
  6. Run Optimization and Maintenance in TechTool Pro.

Repair permissions

When: Repair permissions when things aren't allowed to happen, like opening files, launching programs or saving documents.

What: Permissions dictate who's allowed to do what. Repairing permissions resets these values to what certain applications specify at install. More...


  1. Open the Disk Utility in /Applications/Utilities/
  2. Click your hard drive in the panel on the left (Default is Macintosh HD).
  3. If the "First Aid" tab isn't selected, select it now.
  4. Click "Repair Disk Permissions."
  5. Wait until the repair is finished. If errors occur, repeat.
Tested properties
Time 1min 2sec
Roboficiency + .7%


When: It never hurts to restart your computer.

What: OS X attempts basic maintenance during startup.


  1. Click on the apple in the very top left corner of your screen.
  2. Go down to "Restart..." which is third from the bottom.
  3. When the dialogue appears, click "restart" or just wait for the computer to restart automatically.
Tested properties
Time 30sec
Roboficiency + .19%

Repair disk

When: Repair your disk when you're having startup issues or if you suspect a problem.

What: The built in Disk Utility can find and fix minor disk problems. More...


  1. Insert the OS X install disk that came with your computer.
  2. Restart while holding down the C key.
  3. If prompted, select a language.
  4. Choose Disk Utility from the Utilities or Installer menu.
  5. Click the first aid tab.
  6. Select your volume from the column on the left.
  7. Click Repair Disk and wait.
  8. Restart your computer.
  1. Boot from a second OS.
  2. Open the Disk Utility found in /Applications/Utilities.
  3. Follow steps 5-8 above.
This page has screenshots of every step.
Tested properties
Time 54sec
Roboficiency + .19%


When: If other repair techniques fail for any reason, give DiskWarrior a try.

What: DiskWarrior is a repair utility made by Alsoft.


  1. Insert the DiskWarrior DVD.
  2. Restart while holding down the C key.
  3. Make sure the Directory tab is selected.
  4. Choose your volume from the menu.
  5. Click Rebuild.
  6. Wait. If it gives you the option, choose Replace.
  7. Click on the Files tab.
  8. Click start and wait.
  9. Restart your computer
  1. Boot from a second OS.
  2. Open Diskwarrior.
  3. Follow steps 3-9 above.
Tested properties
Time 52min
Roboficiency + 10.36%

TechTool Pro ~ Maintenance

When: If you suspect a hardware problem, try Techtool Pro.

What: TechTool Pro is a diagnostic and repair utility made by Micromat.


  1. Insert the TechTool Pro DVD.
  2. Restart while holding down the C key.
  3. Make sure the Tests tab at the top left is selected.
  4. Click Check Computer under Test Selection.
  5. Click Check Computer in the bottom right corner.
  1. Boot from a second OS.
  2. Open TechTool Pro.
  3. Follow steps 3-5 above.
Tested properties
Time ≈2hrs
Roboficiency + 8.79%


When: If you're having hardware problems like speaker volume, screen resolution or startup disk selection.

What: PRAM/NVRAM stores hardware information for easy access. More...


  1. Shut down your computer.
  2. Turn your computer on.
  3. Immediately press and hold the Command-Option-R-P keys.
  4. Continue holding the keys as you hear the computer restart and chime two more times.
  5. Release the keys and allow the computer to start as normal.
Tested properties
Time ≈2min
Roboficiency + .85%

Empty caches

When: If settings are screwed up or applications are behaving funny, try erasing your caches.

What: Caches store settings and other information for easy access; erasing them resets these settings. More...


  1. Restart your computer.
  2. Press and hold the Shift key immediately after you enter your login information or before the system automatically logs in.
  3. Use a utility like Onyx or Leopard Cache Cleaner to erase all your system and user caches.
Tested properties
Time 11sec
Roboficiency - 3.53%


When: If your system is slow or broken, or every month or so.

What: Onyx can run a number of different troubleshooting and optimizations at once.


  1. Download Onyx
  2. Restart your computer.
  3. Press and hold the Shift key immediately after you enter your login information or before the system automatically logs in.
  4. Open Onyx
  5. Hit "Continue" if prompted to check S.M.A.R.T. status.
  6. Hit "Continue" if prompted to verify hard drive.
  7. Enter your system administrator password.
  8. Click on the "Automation" tab.
  9. Check all the boxes.
  10. Click "Execute."
Tested properties
Time 49sec
Roboficiency + 2.24%


When: If your system is not on for long periods of time and is starting to get slow.

What: Crontabs run built in maintenance routines in the background on a daily, weekly and monthly basis.More...


  1. Download Onyx
  2. Restart your computer.
  3. Press and hold the Shift key immediately after you enter your login information or before the system automatically logs in.
  4. Open Onyx
  5. Hit "Continue" if prompted to check S.M.A.R.T. status.
  6. Hit "Continue" if prompted to verify hard drive.
  7. Enter your system administrator password.
  8. Click on the "Maintenance" tab.
  9. Click on the "Scripts" sub-tab.
  10. Check all the boxes.
  11. Click "Execute."
Tested properties
Time 43sec
Roboficiency + 2.9%


When: If your system is slow and you haven't installed any apple software for a while.

What: Prebinding looks up and stores information that is required to run programs ahead of time.More...


  1. Download Onyx
  2. Restart your computer.
  3. Press and hold the Shift key immediately after you enter your login information or before the system automatically logs in.
  4. Open Onyx
  5. Hit "Continue" if prompted to check S.M.A.R.T. status.
  6. Hit "Continue" if prompted to verify hard drive.
  7. Enter your system administrator password.
  8. Click on the "Maintenance" tab.
  9. Click on the "Rebuild" sub-tab.
  10. Check the "dyld's shared cache" box.
  11. Click "Execute."
Tested properties
Time 55sec
Roboficiency + 7.62%


When: After moving lots of files large than 20MB or every couple months.

What: Defragmentation puts files together and arranges them in optimal order.More...


  1. Buy Drive Genius or iDefrag and follow their instructions.
If you have a free second hard drive or partition of equal or greater size:
  1. Insert the OS X install disk that came with your computer.
  2. Restart while holding down the C key.
  3. If prompted, select a language.
  4. Choose "Disk Utility" from the Utilities or Installer menu.
  5. Click the "Restore" tab.
  6. Drag your main hard drive/partition from the left to the "Source" field.
  7. Drag your second hard drive/partition from the left to the "Destination" field.
  8. Click "Restore" and wait.
  9. Choose "Startup Disk" from the Utilities or Installer menu.
  10. Choose your second hard drive/partition to start from.
  11. Restart your computer.
*If you can't boot form your second hard drive/partition, erase your main hard drive from the disk utility and restore the version from your second hard drive back to it.
Tested properties
Time 2.5hrs
Roboficiency + 11.52%

TechTool Pro ~ Optimize

When: After moving lots of files large than 20MB or every couple months.

What: Completely reconstructs critical data structures, optimizing them and improving overall system performance. More...


  1. Insert the TechTool Pro DVD.
  2. Restart while holding down the C key.
  3. Click "Tools" section in the top left corner of the window.
  4. Click "Volume Optimization" in the bottom left corner of the window.
  5. Select your hard drive from the menu to the right.
  6. Click "Run Volume Optimization" and wait.
  7. Restart your computer and enjoy.
  1. Boot from a second OS.
  2. Open TechTool Pro.
  3. Follow steps 3-6 above.
Tested properties
Time 2min 45sec
Roboficiency + 13.01%

How to follow along at home:

If you want to: Defragment your hard drive, Run DiskWarrior, Repair with the disk utility, or run TechTool Pro; you will need to 'unmount' your hard drive in the process.
In order to unmount your hard drive(or partition) you must not be booted from it and you must not be running anything from it.
You have three options.
Booting from a hard drive is better than booting from a DVD because it: By installing an operating system on the device you are using you will have a lot less problems with different tools and you can multitask while you are fixing/optimizing things.

Second Hard Drive or Partition

A second hard drive is better than two partitions because if there is a problem with the hard drive itself it will be easier to diagnose, repair and recover.
If your second hard drive is large enough, simply install OS X on it, then install all your maintenance, recovery, repair and optimization tools. If you have any extra space left, check out my partitioning article for ideas on how to use the additional space.
If you want to use a second partition instead of HD you will either need to use an 'on the fly' partitioner like DriveGenius or start out with a hard drive you don't mind erasing.
If your second hard drive or partition is very small--like a flash drive--there is a bootable image which you can copy to any media with the disk utility.

Bootabe CD/DVD

You could burn a bootable CD/DVD for every program you want to run. You would use your OS install disc for the disc utility. You can get the bootable version of DiskWarrior and TechTool Pro. If you want to run iDefrag you will need to download Coriolis CDMaker.
You could try to burn all of them to one master bootable CD/DVD. This is great in theory but a little harder in practice.
The easiest way is to just download and use my bootable image.
The third option is to download TechTool ProToGo or DasBoot. These programs will allow you to create a bootable DVD that will work with your platform.
The downside is that a lot of tools don't work with it. DiskWarrior and TechTool Pro do, however iDefrag doesn't last I checked. The other downside is that believe it or not, not everyone has a DVD drive these days.
The final option is to find and download Leopard 911(by the one-byte-wonder).


There is really more than one matter at hand here. There are the things that you are supposed to do regularly/things that will speed up your computer, and the things that you should do if you have a problem. I will do my best to take them one at a time. I should also point out that when I looked at the different areas of my computer that were sped up in these roboficiencys, it was all of them except OpenGL. Because everything was improved I think it makes sense to talk about saving you overall computer time as opposed to just time rendering a movie or writing things to disk.


There are plenty of people who swear by doing the things I tried but there are just as many who will tell you that they are a waste of time. After looking at the results I am going to have to agree with the former. If you look at how long it took to do some of these things and how much faster they make your system, you can tell that doing them occasionally is beneficial. The real question is, how beneficial and how often should you do them?
That really boils down to how much you use your computer and what you are doing with it. If you are the type of person that is always learning a new programming language, seeing what things can do, has to try every program just to see it work, and does a lot of Video/Audio/CAD stuff, you will probably want to do this on a regular basis. If you are the type of person who writes papers, checks their email, talks to friends and listens to music, you might not need to do this as often. My tests may display much higher results than yours do as I tend to fall into the first category.
Regardless of which group you fall into, how much you use your computer is a big part of it too. Lets look at three examples: TTP Maintenance, iDefrag and Crontabs.
The TTP Maintenance increased the efficiency of my computer by 13.01% and only took three minutes to complete if you take into account a restart. That 13.01% increase saves me 7.81secs for every minute I spend on the computer. That means that after using my computer for about 23min I have already made up for the time it took to run maintenance. It would take me almost 22hrs. of computer use to make up for defragging with iDefrag! It will only take 25mins. to make up for running cron tasks. Does that mean that you should run your crontabs every 25mins? Of course not. These problems build up over time, making the effects of running one of these things greater. The more you do them, the less they will do.
There are also some key differences between the things you do. TTP Maintenance took only 3min, but it was three minutes I couldn't use my computer. Running crontabs on the other hand only took 43sec of which I could be using my computer. These key differences appear in repairing your permissions. Yes, you might not fix your problem but its only 1min that you can even keep using your computer during; so really, what's the harm?
It is also important to realize that these things keep your computer optimized even after you have used your computer to make them worth while. While it will only take you 25min to pay off running crontabs, it wont do as much for you in the future. For instance, lets say that you decide to run your crontabs and defragment your hard drive in succession. After that you start using your computer. After 25mins running the crontabs has paid off but you are regretting ever running the defrag. After 22hrs the defrag has paid off but you are still happy with your decision to run the crontabs because they have saved you 38min now since you have started. However, a little more than 5hrs. after that(29hrs since you started), you decide that defragging was a good after all. At this point both defragging and crontabs have saved you 50mins! The difference between them is that at from now on defragging will save you 4 times as much time. Bare in mind that all those numbers are purely theoretical. The fact is, while you are saving that time you are saving less and less time every hour. After almost 30hrs of computer use your hard drive will be moderately fragmented. If I knew the rate of decline for all the roboficincies I could factor those into the equation although I'm sure that they decline at different rates. Of course, that would also depend on what you do on your computer. If you only listened to music 30hrs. straight, chances are that your hard drive didn't get very fragmented. If you used that time to edit your movie you might have completely refragmented your drive.
I could keep my setup the way it is and every day backup and run the optimization and see how effective it is after x-number of days. That would only really provide information for me, and the amount of time it would take me to do that would by far counteract the benefits of the information it would yield.


Unlike optimizing, none of these tricks were meant to speed up your computer. Other than erasing your caches which proved detrimental to speed(no surprise there) all of the benchmarks were within the margin of error, although it's probably not coincidental that they were all slightly faster. The main thing to look at in these tests is not how much faster they made your computer, but how long they took to do. Repairing my permissions only took about a minute of usable computer time. Chances are repairing your permissions isn't going to fix your problem; but it has fixed some of mine in the past. I would say that you should give it a try. You should also restart your computer and verify your disk. If that doesn't work I would turn to DiskWarrior... unless it is a hardware problem, then reset your PRAM/NVRAM or run TTP Hardware tests. You could also empty your caches. Because that decreases your roboficiency I would try to remove only ones that you think might be causing the problem.


In short, if you computer is acting weird or you know there is a problem, here are some things you should try and the order you should try them in:

If you want to speed up your computer, here is what you should do and a suggested order:

Repair Summery

The most important thing when fixing a problem is to think. Think what you may have done to cause it or what might be done to fix it. Having more than one user on your computer is a good idea. If the problem persists on more than one user you know it is a larger system issue. If it is account isolated you know it is a smaller problem. Diskwarrior tends to help the larger system issues. It is also nice to have more than one partition/hard drive. If a problem persists over another OS installation, check your hardware. It is also very helpful to look online. Rarely do problems only happen to you. There is a lot of useful information on the internet; go get it!

Optimization Summery

If you use your computer for a wider variety of things or a substantial amount of time, running basic maintenance/optimization will pay off. If you are programming and video editing, run them more frequently than if you just talk online and listen to music. The frequency that you run these things is up to you. If your computer is always off when the crontabs are scheduled to run then maybe you should run them manually once and a while. If you don't restart or update things on your computer often maybe you should update your prebindings every now and then. I could never really tell you not to run diskwarrior as it will fix and optimize your hard drive in ways you might not have even dreamed of. It turned out that while defragging does speed you up it also takes a long time to do and may not be worth while for all people. Maintenance in TechTool Pro was about the best thing you could do and I would recommend doing it every so often because it is nice to have TechTool Pro look at you hardware so you can catch a serious problem before it starts anyway.


I began with a blank 250GB internal SATA hard drive. The first thing I did was partition it exactly in half. I installed an operating system and all my software on the first half. I used the first half for a good while until it really started to slow down and get both minor and major problems. After that I booted up from another hard drive and did a full copy with the disk utility from the first partition to the second partition on my new hard drive. From this point on I didn't touch the first partition on that hard drive. I then restarted my computer into the second partition on the new hard drive holding down shift while logging in to prevent login items from starting. I then ran all of my benchmarking tools and recorded the results. I would then try one of the things listed above recording how long it took to run. Finally, I would run all the benchmarks again to see what it did for my computer(allowing a restart before if required). Before you get on my case about that restart effecting the final benchmarks, I did a dry run restart to find its effects.
After that I would boot back into my old hard drive and start the process over. Of course I took the difference between the original and the backup into account.
Here is some useful info before I continue:


Haxial Benchmark
Disk Speed Bench X
Speed Tools

Only some of the utilities provided easy to analyze useful data. Of course I did multiple tests with the ones I used without doing a thing to my system to find their margin of error. Here are the ones I used and their margins of error:

Haxial: .32%
Cinebench: .47%
Cocoabench: 1.17%
Xbench: 3.04%
Finally, here are the specs for my machine in case you want to verify my results:

Xbench Version 1.3
System Version 10.4.8 (8L127)
Physical RAM 2560 MB
Model PowerMac7,2
Processor PowerPC 970x2 @ 2.00 GHz
L1 Cache 64K (instruction), 32K (data)
L2 Cache 512K @ 2.00 GHz
Bus Frequency 1 GHz
Video Card ATY,RV350
Drive Type WDC WD2500KS-00MJB0

It is also important to keep in mind that everything I did that involved unmounting the target disk I did from another hard drive not from a CD/DVD. This greatly reduces the time it takes to do these things and allows me to continue using my computer in the process. Other than that, the reason I did it this was; that is how I would do it in real life. I have found that it makes life SO much easier if you have a repair drive with all your tools installed on it. This makes fixing/optimizing your computer so much quicker and easier. It also helps in diagnosing system wide problems. It is for that reason that I didn't use CD/DVD's and highly recommend that everyone seriously considers getting a second hard drive or making a repair partition on your current one.