General Mac OS X Discussion General Apple and Mac OS X Discussion

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musicopath musicopath is offline
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Lightbulb mac os x needs defrag ? - 11-08-2010, 02:00 PM

Does mac OS X needs an app for defragmentation? I have no idea could you please inform me?

and also what would you suggest for unexpected kernel panics esp. when i am working with ms office for mac?

thanks in advance...

mini 10v, N270, 2GB RAM, 160GB HDD, OSX 10.6.2, NBI0.8.4, windows 7 ultimate dual boot
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Felixz Felixz is offline
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Default 11-09-2010, 12:10 AM

Macs run their own house keeping maintenance scripts daily.weekly,monthly, some people still say they need defragmentation, personally i don't believe they do but if you really still want to try get a copy of 'Drive Genius' it has a Mac defrag. tool, only draw back being it can't defrag the drive it's running from.

about your KP, you really need to give us some more information but a common Kp issue has been the arrow key up-down-side scroll try using either the track pad or bar scroll.

see if that helps any.

Dell Mini 10v 1gb ram 160gb hdd  A04  boot os-OSX.6.7  XP sp3 on Vbox  NBI********51
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cmoney cmoney is offline
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Default 11-12-2010, 04:18 AM

the os defrags anything under 20GB on the fly. repairing permissions every now and then will do enough to keep you speedy. drive genius is good for defrag if you're working with large files.
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fgodfrey fgodfrey is offline
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Default 11-12-2010, 08:21 PM

MacOS doesn't really need defrag for several reasons. First, the underlying block allocation schemes used in HFS are far better than FAT and NTFS (the filesystems used by Windows).

Second, even with better algorithms, you will get fragmentation *but* MacOS automatically defragments files smaller than 20MB. In doing so, it will, over time, clean up the little files scattered everywhere that cause big files to get fragmented in the first place.

Third, modern disk drivers are far better at dealing with fragmented blocks. "Back in the day", you made a request for a block, in the order it was received, waited for the heads and disk to rotate to the right spot, and then read your data. Now, the disk driver chunks up requests in whatever order it determines is best (and preserves the semantics of what you're doing to the file) and then the disk itself can actually cache and reorder data. While I haven't done a test, I suspect that defrag tools on Windows don't get nearly the performance boost that they used to.

Finally, on an SSD (which many of the Dell Mini's have), fragmentation at the level of what you're likely to see simply isn't an issue at all. Because the media doesn't rotate, you don't get appreciably more performance by having no fragmented files.

This article (not written by me) goes into detail on actual performance numbers with HFS and fragmentation: Fragmentation in HFS Plus Volumes
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defrag, mac os x

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