Fragmentation on XFS

Rob Bosch robbosch at
Mon Feb 25 16:14:47 GMT 2008

> Any idea why Glibc's posix_fallocate makes any difference?
> Doesn't it simply write a lot of zeros?  In that case, why doesn't
> rsync writing lots of data sequentially result in the same number of
> extents?

The destination server had a lot of other processes running at the same
time.  I suspect this concurrency is causing the additional extents since
many processes writing to the same disk array.

I thought only 1235 extents without posix_fallocate was pretty good. Under
cygwin and NTFS, an equivalent file was generating around 25000 extents.


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