Hennen Dirk wrote:Linux doesn't use this tool, Why ??
UNIX-like OS such as Linux but also the many *BSD variants (OpenBSD, FreeBSD, etc.) try everything they can to write any data in an intelligent
way to the disks, e.g. they may reserve the right amount of data for a file that needs to be written in advance before the actual write operation happens. This helps to avoid fragmentation from happening in the first place.
Besides that you're not 100% precise. The modern XFS
filesystem for Linux which originates from Silicon Graphics Inc.
) and their IRIX
Unix OS does have a xfs-defrag tool called xfs_fsr
... But you rarely rarely rarely
will ever need it, because under normal circumstances XFS too will usually try everything it can to avoid fragmentation.
I am not 100% sure anymore about this, but I think that for example XFS auto-optimises itself in the background, you just need to leave the system running. If you're not happy you could still use various xfs-* tools to force a filesystem optimisation even while the filesystem is in use. (read the manuals ....)
Ext3 and ReiserFS try hard to avoid fragmentation from happening by paying attention how they write stuff to the disks in the first place; and even if stuff gets fragmented, they usually arrange all the needed extra-infos (inode tables, superblocks, indexes, and what not) in such a way that all the fragmented bits can be found as efficiently as possible.
So defraggers are really not an issue here on Linux (and the *BSD's).
On commercial UNIX platforms such as HP-UX and Solaris they don't even know what a defrag program is ... they never heard of such a stupid thing