Re: [Xen-users] Inaccessible Disk

[Stephen Nelson-Smith <sanelson@xxxxxxxxx>]

Running through the install again via virt-manager, I note:

http://d.pr/i/RBPP

I've seen a similar error earlier in the day on Fedora 18.  I wanted
to be sure this wasn't something related to 4.2 so I went back to 4.1.
 On F18 I saw:

virt-install --name g1 --location
http://mirror.centos.org/centos/6/os/i386 --ram 512 --disk
/srv/xendomu/g1,size=2

Starting install...
Retrieving file .treeinfo... | 668 B 00:00:00 !!!
Retrieving file vmlinuz... | 7.4 MB 00:00:04 !!!
Retrieving file initrd.img... | 57 MB 00:00:39 !!!
Creating storage file g1 | 2.0 GB 00:00:00
ERROR POST operation failed: xend_post: error from xen daemon:
(xend.err 'Device 51712 (vbd) could not be connected. Hotplug scripts
not working.')
Domain installation does not appear to have been successful.
If it was, you can restart your domain by running:
virsh --connect xen:/// start g1
otherwise, please restart your installation.

S.

On Mon, Dec 31, 2012 at 9:32 PM, Stephen Nelson-Smith
<sanelson@xxxxxxxxx> wrote:
> Hello,
>
> I'm a fairly experienced Xen user, with a large number of guests in
> production running atop CentOS 5.
>
> The time has come to refresh this infrastructure, and I've selected
> Fedora as the Dom0 platform.  For now I'm just running some tests on a
> test box, but I'm running into some unexpected problems.
>
> I'm using Fedora 17, which gives me:
>
> [root@dom0-a xendomu]# xm dmesg | grep "Xen version"
> (XEN) Xen version 4.1.4 (mockbuild@[unknown]) (gcc version 4.7.2
> 20120921 (Red Hat 4.7.2-2) (GCC) ) Tue Dec 18 22:30:42 UTC 2012
>
> I've tended to use virt-install as my standard tool, in the past, so I
> had a go with this initially.
>
> I've created a logical volume:
>
> [root@dom0-a xendomu]# pvs
>   PV         VG      Fmt  Attr PSize   PFree
>   /dev/sdb   xendomu lvm2 a--  298.09g 294.09g
> [root@dom0-a xendomu]# vgs
>   VG      #PV #LV #SN Attr   VSize   VFree
>   xendomu   1   1   0 wz--n- 298.09g 294.09g
> [root@dom0-a xendomu]# lvs
>   LV   VG      Attr     LSize Pool Origin Data%  Move Log Copy%  Convert
>   g1   xendomu -wi-a--- 4.00g
>
> And then ran:
>
> virt-install --name g1 --ram 500 --disk path=/dev/xendomu/g1
> --location http://mirror.centos.org/centos/6/os/i386
>
> As expected this gave me a text installer, which I went through in the
> usual fashion.  The install ran all the way through, but on reboot I
> received  the message:
>
> error: POST operation failed: xend_post: error from xen daemon:
> (xend.err "Disk isn't accessible")
>
> root@dom0-a xendomu]# virsh start g1
> error: Failed to start domain g1
> error: POST operation failed: xend_post: error from xen daemon:
> (xend.err "Disk isn't accessible")
>
> Here's the config:
>
> [root@dom0-a xendomu]# virsh dumpxml g1
> <domain type='xen'>
>   <name>g1</name>
>   <uuid>65d06e7c-a69e-3f4a-d403-b5168fb56d5f</uuid>
>   <memory unit='KiB'>512000</memory>
>   <currentMemory unit='KiB'>512000</currentMemory>
>   <vcpu>1</vcpu>
>   <bootloader>/usr/bin/pygrub</bootloader>
>   <os>
>     <type>linux</type>
>   </os>
>   <clock offset='utc' adjustment='reset'/>
>   <on_poweroff>destroy</on_poweroff>
>   <on_reboot>restart</on_reboot>
>   <on_crash>restart</on_crash>
>   <devices>
>     <disk type='block' device='disk'>
>       <driver name='phy'/>
>       <source dev='/dev/xendomu/g1'/>
>       <target dev='xvda' bus='xen'/>
>     </disk>
>     <interface type='bridge'>
>       <mac address='00:16:3e:af:bb:f6'/>
>       <source bridge='virbr0'/>
>       <script path='vif-bridge'/>
>     </interface>
>     <console type='pty'>
>       <target type='xen' port='0'/>
>     </console>
>   </devices>
> </domain>
>
> The device surely exists:
>
> [root@dom0-a xendomu]# ls -l /dev/xendomu/g1
> lrwxrwxrwx. 1 root root 7 Dec 31 20:46 /dev/xendomu/g1 -> ../dm-0
>
> [root@dom0-a xendomu]# fdisk -l /dev/xendomu/g1
>
> Disk /dev/xendomu/g1: 4294 MB, 4294967296 bytes
> 255 heads, 63 sectors/track, 522 cylinders, total 8388608 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x00082140
>
>            Device Boot      Start         End      Blocks   Id  System
> /dev/xendomu/g1p1   *        2048     1026047      512000   83  Linux
> /dev/xendomu/g1p2         1026048     8388607     3681280   8e  Linux LVM
>
> Puzzled as to why this doesn't work, I decided I'd try a different approach:
>
> dd if=/dev/zero of=/srv/xendomu/centos6.img oflag=direct bs=1M seek=3800 
> count=1
> wget http://mirror.centos.org/centos/6/os/i386/isolinux/vmlinuz -O
> /boot/vmlinuz-xen6-install
> wget http://mirror.centos.org/centos/6/os/i386/isolinux/initrd.img -O
> /boot/initrd-xen6-install
> cat <<EOF > /etc/xen/centos6
> kernel = "/boot/vmlinuz-xen6-install"
> ramdisk = "/boot/initrd-xen6-install"
> name = "centos"
> memory = "512"
> disk = [ 'tap:aio:/srv/xendomu/centos6.img,xvda,w', ]
> vif = [ 'bridge=virbr0', ]
> bootloader="/usr/bin/pygrub"
> vcpus=1
> on_reboot = 'destroy'
> on_crash = 'destroy'
> EOF
> [root@dom0-a xendomu]# xm create -c centos6
> Using config file "/etc/xen/centos6".
> Error: Disk isn't accessible
>
> I'm getting the impression I'm missing something fundamental here....
>
> Any hints / suggestions?
>
> Thanks,
>
> S.



-- 
Stephen Nelson-Smith
Technical Director
Atalanta Systems Ltd
www.atalanta-systems.com

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