[Beowulf] clustering using xen virtualized machines
tjrc at sanger.ac.uk
Thu Jan 28 12:34:25 EST 2010
On 28 Jan 2010, at 4:23 pm, Gavin Burris wrote:
> Sorry, I'm not drinking the virtualization/cloud koolaid. I'd love to
> have everything abstracted and easy to manage, but I find
> on an OS or two and keeping things as stock as possible is easier, and
> cheaper to manage at this point. In my situation, virtualization just
> adds complexity and has a price/performance penalty.
For HPC, I think you're probably right at the moment. But for more
run-of-the-mill servers, the cost/benefit and simplification is
definitely good. I've got about 9 physical servers providing virtual
machines for web servers, development nodes, infrastructure services
(mail, and so on) and all that stuff. Those 9 servers are running 170
virtual machines, which in the old days would mostly have been
separate boxes, and in many cases redundant pairs for failover. OK,
so the servers are meatier, and cost maybe four times what the basic
tin we'd have used would have cost for a single server. I still make
that about 75% less money on hardware than we would otherwise have
spent for that number of services. The saving is much larger than
what it cost to buy vSphere. Power consumption is more like a 90%
saving - my entire virtualisation setup consumes about 3.6kW (not
counting the storage), which is, what, about 20W per VM (and we're not
full yet). And it all sits in 9U of rack space.
And then there are all the fringe benefits which save me time;
simplified storage allocation, reduced deployment time, almost
complete elimination of service downtime for hardware maintenance,
guest OS patch management and automated remediation (for Windows, SLES
and RHAS anyway - most of our machines run Debian which sadly they
don't do patch management for). I get HA for free, so I no longer
have to fart about with heartbeat and redundant server pairs. I get
lock-step fault tolerance for free, too, if I need it, so I can
finally get rid of that Marathon abomination. Backups become simpler
(meh, just back up the whole VM with Consolidated Backup).
You're still right that the management of VM setup takes quite a lot
of time, but it's a lot less than if I were having to configure and
deploy the same wide variety of services on physical hardware.
But Cloud stuff, I'm right with you and slightly skeptical at the
moment. Especially for our extremely data-heavy CPU-lite
applications. It's more likely to have application in our line of
work for the ability to ship arbitrary untrusted code to data. My
dream world is for all the sequencing sites to present their data to a
cloud interface in a consistent manner, and if I want to analyse, say,
Broad's data, I just ship my VM to them and run my analysis there.
Similarly, we provide hosts for running their VMs. No more shipping
disks around by Fedex, which is what the scientists currently do. But
it's probably never going to happen. *sigh*. Far too much "not
invented here" politics.
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