[Sheepdog] Backup/Images

[Liu Yuan]

On 10/09/2011 01:07 PM, MORITA Kazutaka wrote:
> At Sun, 9 Oct 2011 11:21:52 +0800,
> Yibin Shen wrote:
>> Use mmap is much simpler than local backup image, and without
>> any influence to consistency. but it doesn't improve availability
>> while whole sheepdog cluster is die(such as some odd network
>> partition issue).
>>
>> anyway, if no one againsts, I will try to implement it in the
>> near future (after we solved most stability issues)
> Can we implement it as an extension of the cache mechanism?  If the
> local cache file has whole data in the Sheepdog VDI, we can regard it
> as a local backup image.
>
> Thanks,
>
> Kazutaka

Maybe we can read-ahead in the whole data if network is not busy 
gradually? When the whole image is read in, we can mark it as 
'complete'.  If some time the cluster crashes, the complete image would 
help the VMs on the very node to survive the crash. The dirty bits will 
be flushed into cluster store in recovery stage.

This would improve availability on the node basis.

Thanks,
Yuan