On Thu, May 10, 2012 at 12:09:36PM +0800, Liu Yuan wrote: > Hmm, DIO object cache doesn't need extra client(gateway node) memory, > this should probably be the default option because then it becomes > completely a disk cache that can survive the host crash. Even then it it consumes disk resources on the gateway. In a setup where networking is very fast and the storage nodes provide low latency I/O that's not nessecarily the right tradeoff - especially not if the gateway nodes have close to no local storage dedicated to the gateway. > Also I want to mention that, for starting up hundreds of (cloned) Guest > VM concurrently, object cache seems to be a must on a massive nodes > cluster. We also get the benefit that all the cloned VM on the same node > would share large scale of cached objects. As said, there totally are use cases for it - just making it unconditional on the sheep side seems like a fairly bad idea. I'd actually love to be able to en/disable it on a per VDI basis. Especially for read-only base VDIs that never get written to during normal operation it seems extremely useful. |