[Openstack] Recovering VMs in OPenStack ESSEX

Razique Mahroua razique.mahroua at gmail.com
Tue Nov 12 08:41:04 UTC 2013


Ok, 
in that case, use kpartx from the host against the disk image to discover partitions:
kpartx -lv /var/lib/nova/[…]/disk
to see if you find any partition

You can as well try to recover it by using a live-cd.
Can you show me the xml file of the domain?

On 11 Nov 2013, at 23:59, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:

> It’s a snapshot and the VM is trying to boot from the snapshot. It’s a linux image.
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 08:53
> To: Narayanan, Krishnaprasad
> Cc: openstack at lists.openstack.org
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> Is it a Linux or a W$ image?
>  
> On 11 Nov 2013, at 23:29, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> It returned “No errors were found on the image”.
>  
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 08:22
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> it’s a different problem now.
> Can you run :
> qemu-img check /var/lib/nova/[…]/disk
>  
> thanks !
>  
> On 11 Nov 2013, at 23:14, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> In the virsh list, I could see the instance status “running”. The GUI seems to be synchronized with the data from virsh. I don’t see an error now. In the VNC I could see an error message “Booting from floppy. Boot failed:could not read the boot disk. No bootable device”.
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 08:12
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> if you run:
> virsh list from the node, is the instance started?
>  
> On 11 Nov 2013, at 22:56, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> I am able to start the VM in virsh. I got a new entry in the GUI but it said Error Spawning.
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 07:31
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> Yes, give the files to the nova.nova user:
> chown nova: /var/lib/nova/etc…
>  
> On 11 Nov 2013, at 22:30, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> 
> Do I have to change the ownership of these two files?
>  
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 07:29
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> yup, should be good : 
> # root > qemu-img create -f qcow2 /var/lib/nova/instances/_base/fc1ff06266a986df09d4293a0be3dbb18884dc1d_0_None 0G
> On 11 Nov 2013, at 22:28, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> 
> 
> I created the base image using the command below. I got a new error “Unable to allow access for disk path /var/lib/nova/instances/_base/ephemeral_0_20_None: No such file or directory”.
>  
> Can I use a similar command to create the ephemeral disk?
>  
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 07:22
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> it’s only an empty file provisioned according to your flavour.
> run this as root:
> # root > qemu-img create -f qcow2 /var/lib/nova/instances/_base/fc1ff06266a986df09d4293a0be3dbb18884dc1d_20 20G
>  
> (pay attention to the last characters, I added the size “20G”)
>  
> Razique
>  
>  
> On 11 Nov 2013, at 22:02, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> 
> 
> 
> Oh I am sorry. I found the disk. You can ignore my previous email.
>  
> I see a new error now
> “error: Failed to start domain instance-0000041c
> error: Unable to allow access for disk path /var/lib/nova/instances/_base/fc1ff06266a986df09d4293a0be3dbb18884dc1d_20: No such file or directory”
>  
> This means that the base image is missing. Can I know is it possible to get this file fc1ff06266a986df09d4293a0be3dbb18884dc1d_20?
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 06:49
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> The _base directory contains only the base (or backing files) images, from which qemu-kvm creates the instance images. 
> Everytime you spawn an instance, OpenStack creates a copy (not exactly a copy) of the image. It puts the base image inside _base (if it doesn’t exist) and create a light image that inherits the changes (the instance) inside /var/lib/nova/instance/instance-UUID/disk
>  
> the disk is linked to that backing file.
>  
> If you haven’t terminated it though, the file “disk” should be there. Is it an instance you’ve been able to use or a new one (meaning you never used it)?
>  
>  On 11 Nov 2013, at 21:45, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> 
> 
> 
> 
> I only rebooted the instance using the GUI. The instance was never terminated. Can I know what is present inside the _base folder in /var/lib/nova/instances?
>  
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 06:40
> To: Narayanan, Krishnaprasad
> Cc: openstack
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> That means the disk no longer exists. Did you terminated the instance?
> if so, then you won’t be able to retrieve it. Maybe you have backups?
>  
> On 11 Nov 2013, at 21:38, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I did as what you had suggested. I see an different error message now.
>  
> “error: Failed to start domain instance-UUID
> error: Unable to allow access for disk path /var/lib/nova/instances/instance-UUID/disk: No such file or directory”
>  
> This means that the disk is missing. Is it possible to create a disk?
>  
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Dienstag, 12. November 2013 05:24
> To: Narayanan, Krishnaprasad
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> No, 
> if you only need the file, create it manually using the prompt:
> root #> touch /var/lib/nova/instances/instance-UUID/console.log
> root # > chown nova. !$
>  
> On 11 Nov 2013, at 20:02, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If I get it correct, it has to be created from the virsh console. Can I know is the following procedure correct for the creation of the instance
> a)      dumpxml the instance that is Shutoff
> b)      create an instance using the output of a)
>  
> If this is the case, it wouldn’t be recognized in OpenStack. Am I missing any link here?
>  
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Montag, 11. November 2013 19:51
> To: Narayanan, Krishnaprasad
> Cc: openstack at lists.openstack.org
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> Try to create it and chown it to nova:
>  
> 
> 
> On Monday, November 11, 2013, Narayanan, Krishnaprasad wrote:
> Hi Razique,
>  
> I executed the start command on the compute node using the domain name option. I got an error message saying that
> Error:“Failed to start domain instance-UUID”
> Error: Unable to precreate char dev file ‘/var/lib/nova/instances/ instance-UUID/console.log: No such file or directory.
>  
> Can I get help to get rid of this problem?
>  
> Thanks,
> Krishnaprasad
> From: Razique Mahroua [mailto:razique.mahroua at gmail.com] 
> Sent: Montag, 11. November 2013 17:22
> To: Narayanan, Krishnaprasad
> Cc: openstack at lists.openstack.org
> Subject: Re: [Openstack] Recovering VMs in OPenStack ESSEX
>  
> You have many solutions for that
> first try to power it on via 
> $ virsh start 
> and check /var/log/libvritd.log
>  
> you can use kpartx to discover the partitions within the images, and use the different builtin system tools to fix the partitions
> fsck.ext4/ xfs_adm, etc…
>  
>  
> Razique
>  
> On 11 Nov 2013, at 04:14, Narayanan, Krishnaprasad <narayana at uni-mainz.de> wrote:
>  
> 
> Hallo all,
>  
> I looked in to forums about recovering VMs in OpenStack ESSEX.  In the dashboard, I could see that the VMs status is “Hard rebooting” with power state Shutoff.  In virsh, I could see that the state is Shutoff. The complete process is taking longer time to finish and I assume it is in a unrecoverable state. Can anybody help me in recovering the data on the VM and the VM itself?
>  
> Thanks,
> Krishnaprasad
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