I generally prefer freely available (in the sense of beer and speech) open source solutions that I can tinker with, but I recognize that sometimes a complete, well packaged and well supported solution is a win. I find it especially nice if I know it is really well packaged open source. As a friend says, “I do not do my own dentistry”
I came across LeftHand Networks http://lefthandnetworks.com/ last fall, and was excited that they were doing a sales presentation in Ottawa in March. What they offer is a virtualized SAN. You run a special virtual machine on each of you diskful physical machines, give them the bulk of your local disk space and these Virtual Storage Appliances (VSA) communicate together than present an iSCSI target. The contents of the disks are replicated (RAID’ed) between machines, so even if one machine goes down, then disk contents continue to be available.
You then point your virtualization infrastructure at this iSCSI target and spin up more virtual machines as guests. This solves an annoyance about the various “live migration” or “vMotion” facilities: you need to have a SAN to make it possible, and the SAN is now a single point of failure, and can be really expensive.
LeftHand supports ESX(i) at present, but my guess is that you can run qemu-img on the vmdk files and boot the thing under XEN. It’s clearly a Linux system inside, and they might even have para-virtualization support in (2.6.26+ kernels have that available), so it might “just work” under XEN, even without HVM (VT/Pacifica).
You can download the appliance and run them, and then you tell two of them to join the same group, and they can replicate disks, and you get 30 days of demo license to do this… I’m at day 15, and it was time to find out what the solution will cost.
I got a quote: $5839CDN. Wow. You can buy physical SANs for that price. You can hire consultants to setup http://www.Openfiler.com for you for that price.
I think LeftHand/HP has missed the boat here. I expected to pay $500 to $900 per system and/or site. (I can see many licensing options here).