[mythtv-users] XFS: options when running mkfs.xfs

Andrew Burgess aab at cichlid.com
Thu Sep 6 14:24:10 UTC 2007

>Though they did not test on XFS, they explicitly mentioned plans to do
>so in "the future."  Though their conclusion was that fragmentation is
>not an issue with any modern filesystem as long as at least 5% of the

I would think a more accurate number would be a multiple of the file
size, like keep 5x or 10x times your typical 4GB file free. Percentage
seems wrong to me (IMHO etc), since the filesystem total size is less
relavant that how the free space compares to the file your're trying to

>space is kept free (so they're unlikely to find that XFS changes that

How do you figure that?

>I still don't think fragmentation issues are a widespread problem (i.e.
>causing performance/usability problems).  I'm just saying that MythTV's
>file system usage is not the type of usage that file systems were
>designed around.  I.e. when <name your filesystem> was created, it was
>most likely not designed to prevent fragmentation of files 10's of
>gigabytes in size that are written out slowly over a period of
>hours--sometimes with multiple such files being written concurrently to
>the same file system.

AFAICS the allocsize= XFS mount parameter is designed to prevent 
exactly that.

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