[BBLISA] RAM speed difference?

[Edward Ned Harvey]

Strangely enough I recently went through this same exercise.  Basically what
it comes down to is:

The blades are highest cost and lowest performance.  The only reason I can
see to get the blades is if you're really tight on real estate.  Holds 2
disks, 2.5" means smaller capacity too.  The blades don't have a caching
raid controller, although they do have hardware support for mirroring, the
disk performance is quite poor.  For fast disks, you have one option only:
SAN.

The 2950's have 8 memory slots, 2U.  Fast internal raid controller with
cache & BBU, able to hold 6 disks.  Assuming you put in at least 4-6 disks,
you end up with 5-20x faster disk than a single disk without the raid
controller.  (Depending on your usage habits.)  If you need to expand later,
you are able to addon external DAS that's also fast, and of course SAN is
also an option.

The 2900's are just like the 2950's, except:   12 memory slots, 4U, and 8
disks.

I bought the 2900's because I have plenty of real estate, and I need 16G
with possibility of expanding without throwing away the old memory.  The
cost difference between 8x2G dimms (with 4 slots open in the 2900) vs 4x4G
(with 4 slots open in the 2950) was significant.




> -----Original Message-----
> From: bblisa-bounces at bblisa.org [mailto:bblisa-bounces at bblisa.org] On
> Behalf Of Scott Ehrlich
> Sent: Saturday, December 22, 2007 5:36 PM
> To: bblisa at bblisa.org
> Subject: [BBLISA] RAM speed difference?
> 
> I'm pricing out some servers (from Dell) and deciding between their
> 1955 blade
> server and a 2950 2U server.   I learned the 1955 has only 4 RAM slots,
> whereas
> the 2950 has 8.  Thus, I could populate with 4 x 4 GB modules, or 2 x 2
> GB
> modules (cost savings).  But, for compute-intensive work, where the
> majority of
> a program will work between CPU and RAM, how much of a cost, compute-
> wise, is
> there, between 4 GB and 2 x 2 GB?
> 
> I could go with 10 blades, or 10 2950 machines.   The benefit of the
> 2950 would
> be more slots for RAM and, with its architecture, easier to manage and
> expand
> (I work with two of the 2950 machines anyway, and have seen the 1955).
> 
> I'm not a/the programmer.  I'm just relaying, and using my resources to
> get the
> best hardware that fits the need.
> 
> Thanks for insight/feedback.
> 
> Scott
> 
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