I may be confusing myself here so I'm asking for some clarification.
I have a large XenServer install that is currently using lvmoiscsi. I am looking for ways to reduce actual disk space usage. I am running ONLY linux VM's in this environment.
The sparse provisioning and chaining that the VHD format supports seems like the ticket but it seems to only support Windows bases VM's using NFS SR's or the the supported StorageLink SR's.
So, can I have linux VM's using sparse provisioning and chaining? Everything I keep reading and what I understand says no. I'm willing to re-work my storage setup if necessary. I currently am using Nexenta filer to serve up my iSCSI LUN's but it can serve most anything out there.
Someone please help me clear this up!!!
Best Answer
This is possible and is actually far easier than I thought it was.
Get your NFS server up and running, use XenCenter (or the xe CLI) to add a new SR to the pool with type of "NSF VHD" and create all your VM's as normal. They will be stored in .vhd format on the NFS server. You can then use your first VM as the parent in a chain of VM's. There are some limitations to the length of the chain but you can read about those in the XenServer docs if you want.
One extremely good piece of advice I picked up during my research was, "DO NOT, EVER, expand your vdi if you have snapshots." If you do you'll have a great time trying to put things back together again.