Skip navigation
This discussion is archived

Defrag in Mac?

8068 Views 10 Replies Latest reply: Mar 24, 2008 12:49 PM by Mac Shunsuke RSS
Mac Shunsuke Level 1 Level 1 (0 points)
Currently Being Moderated
Mar 23, 2008 1:26 PM
Hi, I'd like to know if on Mac's disk utility there are functions similar to "defrag" and "scan-disk" on windows... somebody can help me?
Mac Book, Mac OS X (10.4.10), apple ipod 4 GB
  • Kappy Level 10 Level 10 (221,095 points)
    Currently Being Moderated
    Mar 23, 2008 1:35 PM (in response to Mac Shunsuke)
    No, because OS X defrags all files under 20 MBs on the fly. Since modern hard drives are much faster than in the past it's really unnecessary to defrag a drive, and defragmentation presents a potential risk to your data.

    Kappy's Personal Suggestions for OS X Maintenance

    For disk repairs use Disk Utility. For situations DU cannot handle the best third-party utilities are: Disk Warrior; DW only fixes problems with the disk directory, but most disk problems are caused by directory corruption; Disk Warrior 4.0 is now Intel Mac compatible. TechTool Pro provides additional repair options including file repair and recovery, system diagnostics, and disk defragmentation. TechTool Pro 4.6.1 is Leopard compatible; Drive Genius is similar to TechTool Pro in terms of the various repair services provided. The current version, 1.5.1, is Intel Mac compatible.

    OS X performs certain maintenance functions that are scheduled to occur on a daily, weekly, or monthly period. The maintenance scripts run in the early AM only if the computer is turned on 24/7 (no sleep.) If this isn't the case, then an excellent solution is to download and install a shareware utility such as Macaroni, JAW PseudoAnacron, or Anacron that will automate the maintenance activity regardless of whether the computer is turned off or asleep.

    OS X automatically defrags files less than 20 MBs in size, so unless you have a disk full of very large files there's little need for defragmenting the hard drive. As for virus protection there are few if any such animals affecting OS X. You can protect the computer easily using the freeware Open Source virus protection software ClamXAV. Personally I would avoid most commercial anti-virus software because of their potential for causing problems.

    I would also recommend downloading the shareware utility TinkerTool System that you can use for periodic maintenance such as removing old logfiles and archives, clearing caches, etc.

    For emergency repairs install the freeware utility Applejack. If you cannot start up in OS X, you may be able to start in single-user mode from which you can run Applejack to do a whole set of repair and maintenance routines from the commandline. Note that presently AppleJack is not compatible with Leopard.

    When you install any new system software or updates be sure to repair the hard drive and permissions beforehand. I also recommend booting into safe mode before doing system software updates.

    Get an external Firewire drive at least equal in size to the internal hard drive and make (and maintain) a bootable clone/backup. You can make a bootable clone using the Restore option of Disk Utility. You can also make and maintain clones with good backup software. My personal recommendations are (order is not significant):

    1. Retrospect Desktop (Commercial - not yet universal binary)
    2. Synchronize! Pro X (Commercial)
    3. Synk (Backup, Standard, or Pro)
    4. Deja Vu (Shareware)
    5. PsynchX 2.1.1 and RsyncX 2.1 (Freeware)
    6. Carbon Copy Cloner (Freeware - 3.0 is a Universal Binary)
    7. SuperDuper! (Commercial)
    8. Data Backup (Commercial)

    The following utilities can also be used for backup, but cannot create bootable clones:

    1. Backup (requires a .Mac account with Apple both to get the software and to use it.)
    2. Toast
    3. Impression
    4. arRSync

    Apple's Backup is a full backup tool capable of also backing up across multiple media such as CD/DVD. However, it cannot create bootable backups. It is primarily an "archiving" utility as are the other two.

    Impression and Toast are disk image based backups, only. Particularly useful if you need to backup to CD/DVD across multiple media.

    Visit The XLab FAQs and read the FAQs on maintenance, optimization, virus protection, and backup and restore.

    Additional suggestions will be found in Mac Maintenance Quick Assist.

    Referenced software can be found at and
    Mac Pro 2.66 Ghz; MacBook Pro C2D 2.33 Ghz; MacBook Pro 2.16 Ghz, Mac OS X (10.5.2), Intel iMac C2D 17 "; MacBook 2.0 Ghz; 30 GB iPod Video (Black); iPod Nano 2 GB
  • First Magus Level 6 Level 6 (15,850 points)
    Currently Being Moderated
    Mar 23, 2008 1:36 PM (in response to Mac Shunsuke)
     BlackBook Core Duo, 2 GB RAM, WD 320 GB HD, Wireless Mighty Mouse, Mac OS X (10.5.2), iPod 5G Video, iPod color, iPod 1G Shuffle 
  • M a cB o ok Level 2 Level 2 (335 points)
    Currently Being Moderated
    Mar 23, 2008 1:44 PM (in response to Mac Shunsuke)
    Hello Mac Shunsuke,

    Apple computers automatically defrag and clean the system themselves at 3 am as long as: 1) your Mac is ON at 3 am. 2) you have the "+Put the hard disk(s) to sleep when possible+" deselected. (Under the energy Saver in System Preferences)

    But if you would like to do this manually download this application: (Free)

    Hope this helps!

    MacBook 2GHz 250GB HD 2GB RAM (White) - 20" iMac 2.4GHz (Aul), Mac OS X (10.5.2), AirPort Base (N) w/printer, 500GB Ext HD, 17" Ext Display, 2GB Nano, FireFox 3B4
  • tele_player Level 5 Level 5 (5,380 points)
    Currently Being Moderated
    Mar 23, 2008 2:04 PM (in response to M a cB o ok)
    None of the '3 am' scripts defrag (except perhaps as a side-effect, due to the way OS X keeps certain files unfragmented), and those scripts don't depend on the setting of the hard disk sleep preference.
    MacBook 2.0GhzCore2Duo, 2.Gig, 160G HD, PowerBook G4 1.5Ghz 15", Mac OS X (10.5.1), Logic Studio 8, Focusrite Saffire
  • Sheri Ball Level 1 Level 1 (105 points)
    Currently Being Moderated
    Mar 23, 2008 2:55 PM (in response to Mac Shunsuke)
    It was previously sated, but OS X automatically defrags files 20 megabytes and under. If you do a lot of photo / video / audio (other than iTunes music) you may have larger files.

    If you feel you do need to defragment the disk check out iDefrag:

    Here's Apple's article:

    And here's a couple other resources:

    Hope that helps!
    MacBook 2GHz (CD) White, Mac OS X (10.5.2), 2GB RAM 200GB HD, Problem Free! Aperture 2!! :-)
  • Kappy Level 10 Level 10 (221,095 points)
    Currently Being Moderated
    Mar 24, 2008 11:10 AM (in response to Mac Shunsuke)
    No, there's nothing automatic. This is a manual operation.
    Mac Pro 2.66 Ghz; MacBook Pro C2D 2.33 Ghz; MacBook Pro 2.16 Ghz, Mac OS X (10.5.2), Intel iMac C2D 17 "; MacBook 2.0 Ghz; 30 GB iPod Video (Black); iPod Nano 2 GB


More Like This

  • Retrieving data ...

Bookmarked By (0)


  • This solved my question - 10 points
  • This helped me - 5 points
This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.