[Sheepdog] [PATCH v5 15/17] collie: enable cluster-wide snapshot command

[Liu Yuan]

On 01/05/2012 05:30 AM, MORITA Kazutaka wrote:

> I confirmed some bugs.
> 
>  - If I took a cluster-wide snapshot just after cluster format, I
>    couldn't restore it.
> 
>     $ collie cluster format -b farm
>     $ collie cluster snapshot   
>     $ qemu-img create sheepdog:test 128G
>     Formatting 'sheepdog:test', fmt=raw size=137438953472 
>     $ collie cluster snapshot -l
>     Index           Snapshot Time
>     1               Thu Jan  5 06:34:36 2012
>     $ collie cluster snapshot -R 1
>     Restore failed: I/O error
> 


This is a real bug, we should refuse to perform snapshot operation when
store is not formatted.

>  - 'collie vdi list' shows wrong information after restoring a
>    snapshot.
> 
>     $ collie cluster format -b farm
>     $ qemu-img create sheepdog:test 128G
>     Formatting 'sheepdog:test', fmt=raw size=137438953472 
>     $ collie cluster snapshot     
>     $ qemu-img create sheepdog:test2 128G
>     Formatting 'sheepdog:test2', fmt=raw size=137438953472 
>     $ collie cluster snapshot -R 1
>     Cluster restore to the snapshot 1
>     $ collie vdi list
>       Name        Id    Size    Used  Shared    Creation time   VDI id
>       test         1  128 GB  0.0 MB  0.0 MB 2012-01-05 06:37   7c2b25
>     Failed to read object 80fd381500000000 No object found
>     Failed to read inode header


This is not a bug, we simply haven't implemented it yet. Currently, we
just have basic snapshot support, that is, we can just restore farm's
state, not sheep system state. I leave system state restore to future
patch, since it is not trivial, because we have to take the membership
change into consideration. We are supposed to try it after farm is merged.

Thanks,
Yuan