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XFS / LVM

Posted May 21, 2008 20:29 UTC (Wed) by tarvin (subscriber, #4412)
In reply to: Barriers and journaling filesystems by jengelh
Parent article: Barriers and journaling filesystems

Do XFS' barriers work if the file system is created on an LVM2 logical volume?

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XFS / LVM

Posted May 21, 2008 20:47 UTC (Wed) by nix (subscriber, #2304) [Link]

device-mapper doesn't pass the barriers down, so no. (Actually it asserts 
that it doesn't support barriers, which is safer: the fs can take that 
into account rather than firing off barriers which are just ignored).

(Maybe this has changed recently, but this was the state of affairs a 
month or so back.)

XFS / LVM

Posted May 21, 2008 21:10 UTC (Wed) by jengelh (subscriber, #33263) [Link]

Correct.

[ 51.404922] Filesystem "dm-0": Disabling barriers, not supported by the underlying device [27138.731115] Filesystem "dm-1": Disabling barriers, not supported by the underlying device

Even though I know from before my time of using dm-crypt that only one of sda or sdb does not support barriers at the hardware level.