[sheepdog-users] Few questions about cache

Liu Yuan namei.unix at gmail.com
Thu Jun 6 14:30:07 CEST 2013

On 06/06/2013 07:51 PM, Valerio Pachera wrote:
> What's the difference between 'vdi flush <vdiname>' and 'collie vdi
> cache flush <vdiname>' ?

'vdi flush' just sends a FLUSH request to sheep, while 'vdi cache flush'
do a flush & delete in the collie connected node.

Maybe we should remove 'vdi cache flush' because it can be done by
'collie vdi flush' and 'collie vdi cache delete'. And for a better
naming, we should name them as:

collie vdi cache flush # flush only
collie vdi cache delete # try hard to delete as before

'vdi cache delete' will try to delete all the caches of this vdi in all
the nodes.

> I have a guest running on node 0.
> I kill -9 the guest and start it on node 1.
> Is it safe to remove the cache on node 0 by 'vdi cache delete <vdiname>'?
> In such case, I do not want it to get flushed.

Yeah, it is safe, it just deletes the object cache of this vdi on all
the nodes.

> Is there any known scenario where flushing the vdi cache of a running
> guest may cause problems/errors?

No problems, users can flush it anytime by collie command.


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