[CentOS] md raid 10

Thu Mar 8 15:52:02 UTC 2012
Les Mikesell <lesmikesell at gmail.com>

On Thu, Mar 8, 2012 at 8:33 AM,  <m.roth at 5-cent.us> wrote:
>>> VM's? Sorry, we're doing very serious scientific computing - the couple
>>> or so VMs we had are going away. I mean, when, for example, one guy I
>>> support gets on a 48 core box, and proceeds to fire up an R job, and
>>> uses*all*  of them.... Plus, we're running out of UPSs to stick them on
>>> to, and sockets to reach....
>> ok, so 3 x 48/64 core servers uses the same power as 6 x 4/8 core ?
>> thats still major win.
> Um, no - that's what I'm saying is *not* the case. The new suckers drink
> power - using a UPS that I could hang, say, 6 Dell 1950's off of, *if* I'm
> lucky, I can put three of the new servers. And at that, if a big jobs
> running (they very much vary in how much power they draw, depending on
> usage), even with only three on, I've seen the leds run up to where
> they're blinking, indicating it's near overload, over 90% capability.

Yes, part of the power savings are deceptive - they only kick in when
the CPUs are idle and your users would be one of the rare cases that
peg them for long intervals.   I think this is getting better in the
current generation but haven't followed the latest changes.

   Les Mikesell
     lesmikesell at gmail.com