Re: Xen 3.0.3 tap:aio disk image fails on RAID5/XFS filesystem

[Steven Haigh <netwiz@crc.id.au>]

On Tue, 27 Apr 2010 19:48:01 +1000, Steven Haigh <netwiz@crc.id.au> wrote:
> On Tue, 27 Apr 2010 12:00:54 +0300, Pasi Kärkkäinen <pasik@iki.fi>
wrote:
>> On Tue, Apr 27, 2010 at 05:19:54PM +1000, Steven Haigh wrote:
>>> 
>>> On Tue, 27 Apr 2010 14:01:17 +1000, Steven Haigh <netwiz@crc.id.au>
>>> wrote:
>>> > Hi all,
>>> > 
>>> > Upon bashing my head against a wall trying to get Xen working on my
> new
>>> > hardware I came across an interesting discovery. Every install using
>>> > virt-install was failing and I could only use the file: access
method
>>> for
>>> > my DomUs. Every time I tries to use tap:aio the guest would error on
>>> boot
>>> > saying it couldn't find the root partition.
>>> > 
>>> > My system is as follows:
>>> > OS: CentOS 5.4
>>> > Xen: 3.0.3-94.el5_4.3
>>> > / = 2 x 80Gb HDDs, dmraid1, ext3
>>> > /mnt/raid = 3 x 1Tb HDDs, dmraid5, xfs
>>> > 
>>> > On whim, I moved the DomU images from /mnt/raid/vm-images to
> /vm-images
>>> > and instantly tap:aio worked again.
>>> > 
>>> > This brings me to my question:
>>> > 
>>> > Why would tap:aio fail when the images are on an XFS/RAID5
filesystem
>>> but
>>> > work correctly when on a RAID1/ext3 filesystem?
>>> > 
>>> > To me, this seems like a bug.
>>> 
>>> Oh, and for the record, this is my config file:
>>> 
>>> name = "mail.crc.id.au"
>>> uuid = "929c5a29-10c2-b388-ff01-42110c4ea66e"
>>> maxmem = 512
>>> memory = 512
>>> vcpus = 2
>>> bootloader = "/usr/bin/pygrub"
>>> on_poweroff = "destroy"
>>> on_reboot = "restart"
>>> on_crash = "restart"
>>> #disk = [ "file:/vm-images/mail.crc.id.au.img,xvda,w" ]
>>> disk = [ "tap:aio:/vm-images/mail.crc.id.au.img,xvda,w" ]
>>> vif = [ "mac=00:16:3E:00:00:13, bridge=virbr0" ]
>>> 
>> 
>> Since you're using EL5 distribution you might want to search Redhat
>> bugzilla
>> to see if there are already existing bugreports about this issue.
>> 
> 
> I did have a hunt around - but I couldn't locate anything relevant -
hence
> my post here to see if it is anything that is already known - and maybe
> documented somewhere...

For what it's worth, a bit more digging turned up this:
https://bugzilla.redhat.com/show_bug.cgi?id=217098

As I'm not quite cluey enough to know exactly what was discovered in this
bug report, I can't say for sure if it is related - however I have filed
this: 
https://bugzilla.redhat.com/show_bug.cgi?id=586387

I believe I have tagged this correctly as a kmod-xfs bug - as I don't
believe it is a problem with Xen as such - however any hints /
contributions to the bug report would be appreciated.

-- 
Steven Haigh
 
Email: netwiz@crc.id.au
Web: http://www.crc.id.au
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Fax: (03) 8338 0299