On Jan 21, 2010, at 4:04 PM, Tom Georgoulias <tomg@mcclatchyinteractive.com

wrote:

Ran into a confusing situation today. When I mount an xfs filesystem on a server running centos 5.4 x86_64 with kernel 2.6.18-164.9.1.el5, the barrier/nobarrier mount option as displayed in /proc/mounts is always set to "nobarrier"

Here's an example: [root@host ~]# mount -o nobarrier /dev/vg1/homexfs /mnt [root@host ~]# grep xfs /proc/mounts /dev/vg1/homexfs /mnt xfs rw,attr2,nobarrier,noquota 0 0 [root@host ~]# mount | grep xfs /dev/mapper/vg1-homexfs on /mnt type xfs (rw,nobarrier)

[root@host ~]# mount -o barrier /dev/vg1/homexfs /mnt [root@host ~]# grep xfs /proc/mounts /dev/vg1/homexfs /mnt xfs rw,attr2,nobarrier,noquota 0 0 [root@host ~]# mount | grep xfs /dev/mapper/vg1-homexfs on /mnt type xfs (rw,barrier)

Can anyone else confirm this behavior?

LVM doesn't support barriers.

-Ross