Dave Miner wrote: > james hughes wrote: >> Does ZFS have a feature that allows diffs to be placed another >> space? This would be valuable to Xen clients where all the clients >> are booted off the same golden master. >> > > While we need to have much more conversation with the Xen project > about the topic, I think we'd agree that their current usage model for > that scenario based on the diskless client setup would be vastly > improved by using ZFS clones, which do a form of "another space". I > suspect you're suggesting a much more flexible redirection than ZFS > clones allow, in which case UnionFS or its ilk might be helpful. But > I still wonder at that point if the complications (and resulting > costs) there are worse long-term than spending some time re-thinking > how the system is put together to make such overlay machinery > unnecessary to get "another space" for the pieces which truly need > it. Would probably be interesting for someone to start playing with > the FunionFS stuff from FUSE (assuming we have that working) just to > understand how it might fit.
Another wild idea: Extend the zpool framework to handle a mix of read-only and writable devices. The pool can be imported initially from a R/O device with a R/W device being added later on. The R/W device can host writable clones of filesystems on the R/O device thus providing UnionFS like behavior but being much more time and space efficient. Regards, Moinak. > > Dave
