[Beowulf] RE: Capitalization Rates - How often should you replace a cluster? (resent - 1st sending wasn't posted ).

Greg Lindahl lindahl at pbm.com
Wed Jan 21 13:41:53 PST 2009

On Wed, Jan 21, 2009 at 04:24:13PM -0500, Mark Hahn wrote:

> but I would have guessed search stuff to be  
> disk or memory-dominated.  (both of which have certainly improved over
> the past few years, but much more gradually, no?)

No, we're cpu bound most of the time. We do run the disks hard, but
the bottleneck is cpu.

> ah!  so it appears that disks have improved their active and idle power  
> figures by a factor of ~2 over the past year or so, after having remained
> fairly steady before that.  is that right?  I'm only talking about what
> I think of as the mass market: 3.5" sata.  or do you use 2.5" laptopy disks?
> still only ~10W/disk - I would expect MTBF/AFR/warranty-based considerations
> would more drive your replacement cycle...

Laptop drives are mass market to me, but we don't use them -- we're
too concerned about disk bandwidth... we've got all 3.5" SATA.

-- greg

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