[sheepdog] [PATCH V2 00/11] INTRODUCE

[Liu Yuan]

On 08/21/2012 12:07 AM, Christoph Hellwig wrote:
> Another thing that sprang into mind is that instead of the formal
> recovery enable/disable we should simply always delay recovery, that
> is only do recovery after every N seconds if changes happened.
> Especially in the cases of whole racks going up/down or upgrades that
> dramatically reduces the number of epochs required, and thus reduces
> the recovery overhead.
> 
> I didn't actually have time to look into the implementation implications
> of this yet, it's just high level thoughs.

I think negatively to delay recovery all the time. It is useful to delay recovery
in some time window for maintenance or operational purposes, so I think the idea
only to delay recovery manually at some controlled window is useful, but if we extend
this to all the running time, it will bring cluster to a less safe state (if not
dangerous) at any point. (we only upgrade cluster/maintain individual node only at some time,
not all the time, no?)

Trading data reliability is always the last resort for a distributed system, which highlights
data reliability compared to single data instance in local disk.  

-- 
thanks,
Yuan