----- "Jeff Zheng" <Jeff.Zheng@xxxxxxxxxx> wrote:
> We are trying to control where the files are being allocated on the
> disks, and we tried xfs preallocation. What we found is that each time
> the file being reopened the location of the pre-allocated space could
> change (not all the time). Is there a way to do persistent
> preallocation in xfs, like the same file will always be on the same
> location on the disk given that the requested size doesn’t change?
Sounds like you are truncating the file (on open?), and hence discarding
the preallocation. XFS preallocation is persistent already, so I think
something you are doing must be discarding those preallocated extents.
Could you post a test program, or sequence of xfs_io commands, that would
demonstrate the problem?