[sheepdog-users] changing cache in run time

[Valerio Pachera]

2013/5/27 Liu Yuan <namei.unix at gmail.com>:
> Dynamic resizing object cache with running VM seems very easy to cause
> problems. Is this feature really needed?

I was testing it because I saw it was there and to understand if if
was something useful.

> I can't think of a use case...

I try to figure some (not because I'm needing it, but for users in general):
- I run a cluster without cache for safety etc etc.
  At some point I need a guest to perform fast (maybe just for a day).
  In this case it would be good to have the possibility to enable
cache and disable it later without shutting down the cluster.
- The viceversa. This is actually my production cluster case: it's
running with cache enabled (on all nodes).
  Without 'node cache', there's no way to deactivate it in run time.

> ...because formatted partition can't be sized lively.

I do not know the relation between cache and partition.
I didn't think there was any.

> Currently it is only safe to enlarge it dynamically. I am considering of
> removing 'collie node cache'.

Because it's a cause of troubles, I suggest to remove it for sheepdog 0.6.
If users will request this function, it may worth to reconsider it's
implementation.