[Xen-users] xen-3.2 & barriers

[Christian Kujau <lists@xxxxxxxxxxxxxxx>]

Hi,

I'm using xen-3.2 (from Ubuntu 8.04) and have some trouble with i/o 
barriers. During boot (a paravirt DomU with a more current kernel), 
blkfront reports:

blkfront: xvda: barriers enabled
blkfront: xvdb: barriers enabled
blkfront: xvdc: barriers enabled
blkfront: xvdd: barriers enabled
blkfront: xvde: barriers enabled
blkfront: xvdf: barriers enabled

But as soon as I mount e.g. btrfs or ext4 with barriers support and write 
to the filesystem, I see:

[386046.164004] blkfront: xvdb: write barrier op failed
[386046.164017] blkfront: xvdb: barriers disabled
[386046.164023] end_request: I/O error, dev xvdb, sector 2100400
[386046.164031] end_request: I/O error, dev xvdb, sector 2100400
[386046.164050] JBD2: wait_on_commit_record: sync failed on xvdb-8 - disabling 
barriers

So, is xen-3.2 perhaps not able to handle barriers? Are later versions 
able to handle barriers? (I could not find anything about barriers in the 
wiki)

One more word on the setup: the devices for the domU are LVM2 volumes in 
the Dom0, but I thought LVM could handle barriers, right?

For the record, dmesg and .config for both domU and dom0 are on:

  http://nerdbynature.de/bits/2.6.24-24-xen/

Thanks,
Christian.
-- 
BOFH excuse #246:

It must have been the lightning storm we had (yesterday) (last week) (last 
month)

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