[CentOS] md raid 10

Luke S. Crawford lsc at prgmr.com
Thu Mar 8 15:13:04 EST 2012


On Thu, Mar 08, 2012 at 02:51:58PM -0500, m.roth at 5-cent.us wrote:
> John R Pierce wrote:
> > On 03/08/12 6:33 AM, m.roth at 5-cent.us wrote:
> >>> >  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.
> >
> > ok, how do you figure 3 48 core modern servers are not more powerful
> > computationally than 6 8 core servers?   the 1950's were "cloverton"
> > which were dual core2duo chips, 2 sockets, at ~ 2-3GHz, for your 8 cores
> > per 1U.
> 
> I'm sorry, but to me, the above is a non sequitur. I was talking about how
> much power the servers drink, and that the UPSs that I have can barely,
> barely handle half as many or less, and I'm running out of UPSs, and out
> of power outlets for them in such a small space (that is, a dozen or so in
> each rack), without trying to go halfway across the room.

If you need lots of smaller servers, supermicro makes a very nice single 
socket amd G34 board:
http://www.supermicro.com/Aplus/motherboard/Opteron6000/SR56x0/H8SGL-F.cfm

I have a bunch of those in production, and they work well. Most of mine only
have 32GiB ram;  I bought them back when 8GiB modules were expensive;  but 
if I bought one today, they'd have 64GiB, as 8GiB reg. ecc ddr3 is cheap
now.  They use more than half what a dual G34 board with double the ram/cpu 
would use, but not a lot more than half.  

One of those single-socket G34 boards should use rather less power
than a dual-socket 1950 with FBDIMMs and it should give you rather more
compute power and ram. (ugh.  as someone that uses a lot of ram and pays a 
lot for power, I hate FBDIMMs.  I was almost entirely AMD socket F during 
that time period for the reg.ecc ddr2.  all my new stuff is intel 56xx 
with reg. ecc ddr3.) 

Also, they make lower power G34 CPUs... they cost a bit more, but when 
you are paying California prices for power, it's usually worth it, especially
if you plan on keeping the thing for 5 years rather than just 3. 



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