Wilkins, Vern wrote:
I agree, all the talk of certain filesystems not needing defragmentation (not
just XFS), is all just talk. In the real world I have seen heavy
defragmentation on all my machines, regardless of filesystem. All it takes is
a limited amount of freespace and/or a lot of file creation/deletion. Mail
servers as already mentioned are a good example of the heavy file
creation/deletion scenario, as are audio/video editing workstations. On a/v
editing workstations I have seen greater than 90% fragmentation in a fairly
short time using virtually any filesystem. The ability to easily defrag XFS is
pretty significant in my choice of filesystems.
There are, however, things that can be done to limit/reduce filesystem
fragmentation. XFS uses delayed allocation, meaning that blocks for a
file are not immediately allocated - this allows the allocator to
allocate more blocks at a time, and do a more efficient job of keeping
blocks in a file unfragmented.
On the other hand, some applications are just brutal for filesystems -
go download a linux distro iso image via bittorrent & see how many
extents you get!
-Eric
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