[sheepdog] read/write during recovery

[Dietmar Maurer]

> It is only safe to run the command if none of the nodes is recovering, you
> said you have node failure event all the time, so there isn't any window for
> you to run the command.

Your target are system with 1000 nodes . Let's say average lifetime of a node about 3 years.
So you get about one node failure per day.

But recovery and cleanup actions can take several hours, so it is quite hard to find a window
on such system?