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On Thu, 3 Jun 2010, Paul Hirst wrote:
On Thu, 2010-06-03 at 13:54 +0100, Gordon Henderson wrote:On Thu, 3 Jun 2010, Paul Hirst wrote:We are using DRBD + OCFS2 + KVM here to provide a redundant virtual hosting solution. If you added a bit of monitoring and automatic failover that's pretty much the solution you are looking for. Live migration already works like a charm so adding failover should be simple enough, we just haven't bothered yet.Hm. that's intersting - but doesn't OCFS2 negate the need for DRBD???OCFS2 is a shared access filesystem built on top of a shared block device. Usually you would expect the shared block device to be a SAN but you can instead use DRBD (in master-master mode) for a similar (and generally much cheaper) result.
Of-course. I'm obviously having a brain-fart week - being frustrated with the client I mentioned below - been going through various scenarios to help them maximise storage for their little cluster fork of boxes for a particular application. Mean no-money startups who inherit old kit. Bah.
I did look at OCFS many (7?) years ago and wasn't sure of it's stability then, but just had a quick look now and it's looking very intersting - and I've a client who may benefit from it too... Do you have any idea of performance of it?All I can really say is it's 'fine'. We have DRBD running over a crossover cable to it's pair machine, so that runs at a gigabit. We don't currently have any performance concerns and I haven't run any benchmarks. I was going to run bonnie++ on the OCFS2 filesystem and on a local ext4 filesystem just to see the difference, but it claims I need to use file sizes which are more than twice the amount of ram. The machine has 12G of ram and I don't have 24G of free disk space without moving some things around, so for the moment I'll have to leave it. If I ever get round to doing some benchmarks I'll post the results.
It's to overcome RAM caching of the data - you can force bonnie to run with less than that - try it with just 1MB and look at the results :)
Gordon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html