Bryn M. Reeves wrote: > David Brown wrote: > > Of course, any of the re-ordering (SCSI TCQ, or SATA NCQ) requires > > filesystem and driver support of write barriers for reliability. > > Write barriers are not implement in DM, hence LVM, so there is a > > Only the dm-mpath and dm-snap targets treat barrier bios specially (they > return EOPNOTSUPP). Other dm targets pass the barriers on to the > underlying devices unchanged. A simple lvm volume, mounted with XFS gives the following kernel message: Filesystem "dm-11": Disabling barriers, not supported by the underlying device XFS mounting filesystem dm-11 so I'm fairly sure that the write barriers don't work. This is the 2.6.20 kernel. XFS is the only filesystem nice enough to warn you that the result might not be as reliable. Dave _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
