Fragmentation on XFS

[Jamie Lokier]

Rob Bosch wrote:
> Destination file on XFS

> 	- ftruncate, 59GB file, Execution time 52776 secs, 1235 extents
> 	- posix_fallocate, 59GB file, Execution time 53919 secs, 11 extents

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?

-- Jamie