Open Stack

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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