Comments on: Does Linux, Mac OS Need Defragmentation Software?

By: Gnoom

Gnoom — Wed, 12 May 2010 15:20:42 +0000

It is a myth that Linux and/or OS X file systems do not fragment. OS X on-the-fly defragments files smaller than 20MB, though. My current Linux install is about a month-old, and fragmentation figures for my partitions are as follows:

/ fragmented files: 36.973%; average fragments per file: 1.339

/home fragmented files: 78.920%; average fragments per file: 2.879.

Note: I am running ext3 for both / and /home. Running a file system that supports extents and/or delayed allocation (e.g. xfs or ext4) should reduce fragmentation, but I don’t think fragmentation will ever be zero in any case.

Regarding performance implication of fragmentation in Linux and/or OS X, I haven’t seen any convincing benchmarks that could tell me whether there’s a performance degradation as a result of fragmentation or not.

In conclusion, I would say that one should not worry about fragmentation as long as his/her computer performs normally.

By: Ryan Farmer

Ryan Farmer — Thu, 30 Apr 2009 09:33:26 +0000

Data fragmentation is really never a problem on Linux file systems (it can be, but you’d really have to beat the crap out of the file system and leave it with very little free space)

Ext2/3 are probably the most vulnerable, and after 2 years of daily use on an Ext3 partition, it was 1.9% fragmented.

XFS has xfs_fsr which you can invoke to “defragment” the file system, but it fragments even less than Ext2/3 do and the package which brings in xfs_fsr is not usualyl even installed by default (xfsdump).

Ext4 will have E4defrag, which is basically just a front end to the functionality that’s already in the kernel/driver.

Really fragmentation is an afterthought because most of the reason, I think, Microsoft keeps NTFS with the behavior it exhibits is because Executive Software and Raxco are both MS partners and pay them a percentage of their sales.

There’s really just no reason to design a file system that is susceptible to this. You also risk data loss on NTFS due to file fragmentation in some cases.

By: Connor Bryant

Connor Bryant — Sat, 25 Apr 2009 22:49:58 +0000

It’s one of the things PC’s have that Mac’s don’t.

By: gozlag.com » Such is the Life of a Geek

gozlag.com » Such is the Life of a Geek — Sat, 25 Apr 2009 08:31:24 +0000

[...] Do Linux or OS X need defragmentation software? [...]

By: 3G Chromakey ~ Windows Fanatics

3G Chromakey ~ Windows Fanatics — Sat, 25 Apr 2009 01:00:22 +0000

[...] Do Linux or OS X need defragmentation software? [...]

By: Roy Schestowitz

Roy Schestowitz — Fri, 24 Apr 2009 20:17:31 +0000

I keep seeing people who bring up the Net Applications figures, which are Apple|MS-sponsored. http://boycottnovell.com/2009/02/04/microsoft-apple-net-applications/

By: bob

bob — Fri, 24 Apr 2009 20:11:07 +0000

Linux only needs defrag if the hard disk is getting full.

Otherwise, no it doesn’t.

Linux does have defrag tools, but they only work if you unmount the disk before you run them – not practical in many cases (especially if you want to defrag the drive with /bin on it)

By: Gary Greene

Gary Greene — Fri, 24 Apr 2009 15:47:51 +0000

As a distribution developer that pays attention to filesystem development, I know for fact that fragmentation of files and of data segments CAN occur. Ever had a crash in Linux and then watched as fsck happily told you that you have 8.9% or more fragmentation? Yes. While in most cases, it is file and not data segments that are strewn across the drive, it does occur in those cases. I use XFS for the very reason that it has a “defrag” utility as part of it’s toolset. Mind, I’d love to see if the tool from Diskkeeper will include optimising directories, since on a mail server that would be killer.

By: kesav

kesav — Fri, 24 Apr 2009 15:37:17 +0000

FWIW, I use Diskeeper 2009 Pro on my 2 XP desktops and a vista notebook, and it does a great job. Never had a problem with it, and it’s been unintrusive but efficient in doing it’s work behind the scenes. I don’t intend on switching to Mac or Linux any time soon, but I would be curious to see what the Diskeeper guys come up with.

Searching for OS X on the DK site throws up this field study exercise. Have any of you guys participated?
http://www.diskeeper.com/blog/post/2009/02/04/Mac-Fragmentation-Field-Study.aspx

By: Ron Schenone

Ron Schenone — Fri, 24 Apr 2009 11:50:07 +0000

Again, thanks to all of you who have made a comment. I learned something new.