Fragmentation on XFS

[Rob Bosch]

> 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.

Rob