Does Linux, Mac OS Need Defragmentation Software?

Linux and the BSDs don’t have a file fragmentation problem, but they can, and do, have problems with complete files scattered all over the drive. The standard way to defrag a slice in any of the Unix types, or clones, has been to backup that slice (partition) reformat, and then copy the partition back to the drive. Time consuming, tedious, and really unworkable since drives got to be measured in gigabytes.

I’ve seen programs that will do the task, but they are not widely used, mostly due to the myth that no fragmentation occurs.

Funny to run across your Tweet not 60 seconds after deleting latest DiskKeeper offer from my email.

I have used DK for years on my PCs but have recently (a few weeks ago) moved to a new iMac 24″ machine. I used VMWare’s utility to copy my PC and now run it and all of it’s programs, settings, and data as a Virtual Machine on the iMac.

I was wondering whether the Mac needs disk defragging, so I am interested in hearing what other readers have to say on this topic. I am an MCSE, CCNA and A+ and Network+, but I am a newb when it comes to Mac.

Best regards,

jerry

My understanding is that Linux and Macs do it on the fly. I’ve been using Macs for over 10 years and have NEVER even thought about “defragging”. No issues here!

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Thanks for the information everyone and for your comments.

I just cloned my 120GB on my mac to a fresh 500GB and now the 500Gb is sitting inside. First thing I noticed after switching the disks was that my mac was running slower than before. So I opened iDefrag and there it was, fragmentation everywhere, everything was red. I guess you do need to defrag your mac but only in special cases like mine. But in most cases I think the common belief that macs don’t need to be defragged is quite truthful.

Iin the case of Linux ( I have hands on experience with most of the major distros) due to the partition structures of the OS in general do not develop slowing symptoms as does with Windows. Ubuntu 8.10 has a nifty utility for clearing the OS caches though.

Linux will be adding online defragmentation to its toolkit for at least one of its file systems, ext4.

I’m not sure I buy the kernel changes argument though since most of the linux file systems have been exceedingly stable for a fairly long time. I think it has most that they’ve figured out a way to market it.

In one word: No.

Use XFS.

xfs_fsr -v is your friend.

On the Mac, defragmentation is not as big a problem. However, that’s not to say that it doesn’t exist.

As far as I know, what it means is that whole files are kept defragmented, but this doesn’t mean that related files (eg in a program) are kept together.

Mac OSX only defrags files below a certain size, and core parts of the system on installs. For those who do a lot of image and/or audio work, maybe those who try a lot of different apps too, a defrag done regularly makes a significant difference. I use iDefrag (from Coriolis Systems), and would have to clean install once a year or more if I didn’t. I would never be without it.

Basic computing, or computing that doesn’t produce large quantities of data won’t be an issue for Mac OSX

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

Disk fragmentation doesn’t happen often because Linux/OS X file systems check to see if there is enough space for a full file, rather than throwing the data into the first blank spot.

the oracle is right, however. Files may be complete but could be strewn across your HDD. There are already tools to optimize your HDD, though. iDefrag for OS X. I couldn’t find one for Linux, though.

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I once found a demo of an app. called iDefrag but it was limited to drives of 100MB> (being a demo and all) but it did show me fragmentation on my HDD

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

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

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.

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)

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/

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

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

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

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.