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RE: [Xen-users] block-attach on dom0 missing

To: "'Tanuj Bansal'" <bansal.tanuj83@xxxxxxxxx>
Subject: RE: [Xen-users] block-attach on dom0 missing
From: "Dustin Henning" <Dustin.Henning@xxxxxxxxxxx>
Date: Fri, 18 Dec 2009 11:02:37 -0500
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        Have you been able to mount other partition images to dom0 with
block-attach?  What about mounting this partition image (or others) to domUs
with block-attach?  If you could, were they using the same kernel as dom0?
I don't have my notes on block-attach with me, and I have only used it on
HVM domUs thus far, but those would be basic troubleshooting steps that
might help you resolve this issue.  I should think block-attach should work
in dom0, but I don't know this for a fact.  I don't even know whether you
can attach anything to PV domUs (dom0 is PV) with block-attach, much less
partitions (vs full disks).
        After re-reading your config, it looks like you are using a disk
image, not a partition image.  In that case, at the very least, your command
should change to this:
xm block-attach 0 tanuj.dsk /dev/xvda w 0

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tanuj Bansal
Sent: Friday, December 18, 2009 02:20
To: Pasi Kärkkäinen
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] block-attach on dom0 missing

Yes, I know to use kpartx and it is easy but need to know this also...please
let me know...where is attached device

On Fri, Dec 18, 2009 at 12:47 PM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
On Fri, Dec 18, 2009 at 12:33:37PM +0530, Tanuj Bansal wrote:
>    I have one domU using the disk file tanuj.dsk
>    [root@tanuj-xen-new virtual]# cat /etc/xen/tanuj
>    name = "tanuj"
>    uuid = "3d9ab75d-e08f-bac9-b56c-1cd6a43d1e35"
>    maxmem = 300
>    memory = 300
>    vcpus = 4
>    bootloader = "/usr/bin/pygrub"
>    on_poweroff = "destroy"
>    on_reboot = "restart"
>    on_crash = "restart"
>    vfb = [  ]
>    disk = [ "tap:aio:/virtual/tanuj.dsk,xvda,w", "phy:/dev/sda11,xvdb,w" ]
>    vif = [ "mac=00:16:3e:32:e9:5f,bridge=xenbr0" ]
>    [root@tanuj-xen-new virtual]#
>    and this domU has disk /dev/xvda1 mounted at /boot
>    [root@tanuj ~]# df -h /boot
>    Filesystem            Size  Used Avail Use% Mounted on
>    /dev/xvda1             99M   13M   81M  14% /boot
>    [root@tanuj ~]#
>    now I am trying to attach that /dev/xvda1 on my dom0
>    #  xm block-attach 0 tanuj.dsk /dev/xvda1 w 0
>    Now I can see the attached device in xm list --long

>    But I am not able to locate that disk /dev/xvda1 on my dom0 and how can
>    mount it even if my domU is down
>    I know that the /dev/xvda1 data can be taken by using losetup and
>    but need to know about this
Why do you need this? just use kpartx (no need for losetup), it's much
easier and it works.

-- Pasi

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