On Windows, there is Disk Defragmentor that runs every so often to make files contiguous again.

I explain this to users in lay-men terms, but at the same time, I would like to mention yet another +1 about our company, but really have no understanding of the Solaris process to even know if that would work, so how is it done in Solaris?

If it is different depending on filesystem, I it would be nice to know about ZFS, UFS, and whatever the most popular Linux filesystem is.


1 Answer 1


The most popular Linux files systems are ext2/3/4, xfs, reiserfs and the upcoming btrfs. None of these files systems need to be routinely defragmented. Other care can be taken, but that isn't part of regular maintenance. Constant fragmentation is a problem peculiar to windows file systems.

From my knowledge of zfs it doesn't either, but my knowledge of ufs is limited.

  • UFS fragmentation information can be found here
    – user591
    Jun 7, 2011 at 20:38
  • @Caleb strictly speaking EXT2/3/4 can fragment but only if the volume is nearly full. Jun 7, 2011 at 21:25
  • 4
    Strictly speaking, all the usual unix filesystems can become fragmented. It's just that they don't quickly tend to become fragmented the way FAT32 and NTFS, especially if your disk isn't almost full. Jun 7, 2011 at 22:25
  • @Amazed and @Gilles are of course correct, the technically possibility exists. I changed the tone of my answer a little bit to reflect this. Any system that has been run at full disk capacity for any length of time likely suffers some. Usually doing normal housekeeping on the files will allow the filesystem to do it's job and houseclean internally. I believe a few ext tools even exist to force this, but as a general system admin procedure they are not needed.
    – Caleb
    Jun 7, 2011 at 23:06
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    I wouldn't limit fragmentation-as-a-problem to Windows. Other filesystems that allocate in extents or runs, like ODS-2 or SGI's old EFS, needed regular defragging. UFS, ext2/3/4, allocate files by block, so non-contiguous files don't mess up performance as obviously.
    – user732
    Jun 7, 2011 at 23:50

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