[Grml] EXT3-fs: barriers not enabled

Christian Hofstädtler ch at grml.org
Tue Jan 18 09:14:45 CET 2011


On Tue, Jan 18, 2011 at 2:22 AM, Sven Crouse <svenc at snet.net> wrote:
> I just finished migrating Gentoo from single partition to mirrored
> ( RAID1 ) and LVM2 volumes.  In the process, I learned/realized that the
> Ext3 filesystems contained within raid/volume group are not enabling
> write barriers despite being told by fstab to do so.  This is 2.6.36
> kernel with lvm2 version 2.02.73.  I thought to try to grml 2010.12 as
> well, but problem remains.

This probably means that the underlying blockdevice does not support
write barriers.
2.6.36 should support write barriers in the md and dm layers, but your
underlying block device still has to support that, too.

> My question:  is there any magic "Start" besides mdadm-raid, lvm that
> should be necessary ?


You could try running your test with a stock Debian kernel and see if
it works there, just to do a quick verification.


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