Re: [Openstack] Recover data after VM crash

2012-10-12 Thread Vishvananda Ishaya

On Oct 12, 2012, at 9:10 AM, Ben  wrote:

> Hi the list,
> 
> I have an instance in inconsistent state, and I would like to recover the 
> data stored in.
> 
> The story : I had a very high load average on the instance, so I decided to 
> reboot it with nova reboot command. The instance didn't went up (may be root 
> fs corruption ?), so I tried to rescue it with nova rescue command.
> 
> Now when I try to start the instance, I see in the compute log an exception 
> message telling that kernel.rescue file is not present. Same thing if I try 
> to unrescue (playing with state in db to allow the command).
> 
> So I'm stuck with a probably broken image, in a broken rescue state.
> 
> Questions :
> - how can I rescue or unrescue the instance ?

Does your instance have a separate kernel and ramdisk? I'm not quite sure what 
went wrong with rescue, but you might try navigating to the instance directory 
and doing something like
cp kernel kernel.rescue
cp ramdisk ramdisk.rescue

You could also attempt to change the xml in libvirt to get it bootable again 
using virsh
virsh dumpxml 


> - how can I recover the data (by mounting instance file to browse its content 
> ?)

You can mount the instances root filesystem using qemu-nbd.  An example of 
doing this is in my nova-debug script here:

https://github.com/vishvananda/novatools/blob/master/nova-debug#L51

Vish


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[Openstack] Recover data after VM crash

2012-10-12 Thread Ben

Hi the list,

I have an instance in inconsistent state, and I would like to recover 
the data stored in.


The story : I had a very high load average on the instance, so I decided 
to reboot it with nova reboot command. The instance didn't went up (may 
be root fs corruption ?), so I tried to rescue it with nova rescue command.


Now when I try to start the instance, I see in the compute log an 
exception message telling that kernel.rescue file is not present. Same 
thing if I try to unrescue (playing with state in db to allow the command).


So I'm stuck with a probably broken image, in a broken rescue state.

Questions :
- how can I rescue or unrescue the instance ?
- how can I recover the data (by mounting instance file to browse its 
content ?)


Thanks

Ben

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