Actually, let me clarify my original question, as re-reading it seems like it was misleading. Since all hypervisors don't support this capability (for example, XS doesn't), but a zone can be heterogeneous (from a hypervisor perspective), we need to support the capability to allow both zone-wide and cluster-only primary storage for any zone. I was wondering if a single cluster needs to support both, seems like it is a nice to have?
Can you elaborate on the "disk offering" comment - are you suggesting we provide the end user the following choices a) local disk (we have this today already) b) zone wide (new - but we indirectly provide this capability already, as CS copies between primary stores if needed - but explicitly choosing this option means finding storage only on the shared store. If not chosen, preference is to place in shared store, if not possible place in cluster-specific primary store we still may not be able to avoid "double" copy - if we have to unmount the disk and remount on a cluster that does NOT have shared zone-wide primary store (or vice-versa), we still may have to resort to the double copy as is done today - Hari -----Original Message----- From: Alex Huang [mailto:alex.hu...@citrix.com] Sent: Thursday, January 3, 2013 1:51 PM To: cloudstack-dev@incubator.apache.org Subject: RE: [DISCUSS] Zone-wide primary storage target > -----Original Message----- > From: Hari Kannan [mailto:hari.kan...@citrix.com] > Sent: Thursday, January 03, 2013 1:46 PM > To: cloudstack-dev@incubator.apache.org > Subject: RE: [DISCUSS] Zone-wide primary storage target > > Hi Alex, Chip, > > That's easy, I will change the name :-) > > @ Alex, I wasn't explicitly expecting co-existence of zone-wide > primary storage and a "local" (cluster-wide only) primary storage. It > seems you have assumed that would be a basic requirement, just wanted to > confirm. No I was giving one use case of where this capability might be useful. It's not a requirement. > > If that were the case, when a user requests a data volume, must there > be an option to choose or how will the allocation work? Will data > volumes always come out of the zone-wide storage and root volume > always is local or cluster- based primary storage? I assume those will go into the disk offering. > > Finally, should we allow multiple zone-wide primary storage? Yes. Every time we plan for only one, it has come back to bite us because physical limits of the resources. We can certainly present to the end user as one zone wide ebs like storage but how it's implemented underneath shouldn't be limited. --Alex
