Nick Fisk wrote: "So it looks like each parallel IO thread is being allocated next to each other rather than at spaced out regions of the disk." It's possible that the "filestreams" XFS mount option may help you out. See: http://www.xfs.org/docs/xfsdocs-xml-dev/XFS_User_Guide/tmp/en-US/html/ch06s16.html Regards, Richard