[sheepdog] read/write during recovery

[Dietmar Maurer]

> On 07/26/2012 04:06 PM, Dietmar Maurer wrote:
> > But recovery and cleanup actions can take several hours, so it is
> > quite hard to find a window on such system?
> 
> We are always optimizing the recovery performance. For now, 30 nodes with
> dozens of TB data, the recovery process is less than 30 mins. Note, recovery

Likelihood of node failure during cleanup is still very high on such system. 
Lest say both recovery and cleanup takes 30min, likelihood that they occur at same time
is about 1/48 (> 2%).