Dump ext3, use xfs.

Edit: oh wait, I just realize that CentOS does not provide xfs - which means you'll need to dump CentOS or compile your own kernel but I don't know whether those are acceptable options.

When hard drives were much smaller than they are today, they were routinely close to being "completely filled up." When files were added or expanded, it was fairly unlikely that sufficient large blocks of contiguous free space existed, anywhere, period. So, "fragmentation" was a fact-of-life, as much because of the problem of "being almost completely filled up" as anything else.

These days, space is usually plentiful. But disk and disk-controller hardware is a lot smarter, too. There is often copious amounts of unused RAM which can be devoted to file-buffers. So the practical impact of fragmentation is for the most part "gone."

Does fragmentation continue to exist? As I said earlier, yes, but it's academic: nobody's "screaming." Some filesystems and storage systems rearrange files on the media for various reasons, but the payoff of a "disk defragmenter" program has vanished.

Are you saying there aren't really electrons and atoms and orbits? I think even in university, that is the official story.

Unless you get into quantum mechanics, which is highly specialized.

Do you really have to revive a thread that has been sleeping for 2 years to react on a post that's over 3 years old

LOL. The thread was sleeping so soundly and happily for 2 years! I am just a troublemaker. We can drop it.

In the very old days when I went to school on this stuff this is the answer I was told.

Backup to tape each night and restore in morning. Backup with tar to tape puts every file in order (some order but not fragmented).

Everyday your system will be both backed up and tested and defragged.


We still back up some systems to tape but the sad fact is tapes can't keep up with the amount or speed needed anymore so you have to back up to some networked or attached raid if you can do it.

Instead of backup you may be able to use other tools depending on what is going on. VM's can compact virtual disks and you can still tar over to a image and back. Might be other ways.


Cat and chunk may be able to fix some single files.

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I note that the next Fedora release will dump the whole ext file system tree in favor of the btrfs (which is fully supported in the new 3.0 Linux kernels). My understanding (from reading, no experience) is that you really don't need to defragment btrfs file systems because the storage medium usage (and access) is optimized by the file system's internal structure.

Since Fedora is Red Hat's "test bed" for new things, if the Fedora experience is positive, newer Red Hat (and CentOS) releases may move to the btrfs in a year or two.

First of all, defragmenting a filesystem in Linux while it is mounted could be a very bad thing.

Secondly, 9 out of 10 times filesystems under Linux generally DON'T need to be defragmented. However, since you seem adamant about making this happen for you, may I suggest the following link:

http://polishlinux.org/apps/cli/defr...x-filesystems/

Just remember that it is a good idea to have a least 10% of the filesystem you want defragmented available for the entire process to be successful. And don't forget, UNMOUNT THE AFFECTED FILESYSTEM BEFORE YOU RUN DEFRAGMENT!

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