HP’s New 32GB DIMMs Too Expensive?

A reader recently commented on my article about HP’s new 32GB DIMM, “At $8039 per DIMM, HP can support 384GB in a BL460c at the cost of $96,000 per server just for the memory! If you filled just one rack with these servers, you would spend $6 million just for the memory. And the memory would run at a paltry 800MHz.
Cisco can stuff 384GB of RAM into a B250 blade for almost one fifth the cost using 8GB DIMMs… and run that memory bus at 1333MHz. I realize the Cisco B250 is twice as big as the HP BL460c, but when you’re saving $75,000+ in memory on EVERY SERVER and getting better performance out of that memory, you can afford to buy an extra slot in a blade chassis
.”  This reader brought up some good points, so in today’s article, figured I’d dig into this a little.

First, let’s examine the maximums (per 42U rack):


Cisco UCS B250 M2 (using 8GB DIMMs)
HP BL460 G7 (using 32GB DIMMs)
28 servers 64 servers
56 CPUs 128 CPUs
448 cores 768 cores
10.752TB Max Memory 24.5TB Max Memory

The table above shows that the HP BL460G7 with 32GB DIMMs offers a higher server density, more CPUs and cores as well as memory over the Cisco B250 M2.  As the reader commented in the opening above, the Cisco UCS B250 M2 offering is much cheaper but is half of the max memory of the HP 32GB DIMM offering.  Based on the differences in the table, I’m not sure comparing the Cisco UCS B250 M2 with the HP BL460 G7 with 32GB DIMMs is a fair comparison.  Perhaps a better comparison would be to look at the HP BL460 G7 using 16GB DIMMs per 42U rack: 


Cisco B250 M2 (using 8 GB DIMMs)
HP BL460 G7 (using 16GB DIMMs)
28 servers 64 servers
56 CPUs 128 CPUs
448 cores 768 cores
10.752TB Max Memory 12.28TB Max Memory

The full-width form factor of the Cisco B250 M2 limits the quantity of servers you can into a 42U rack, which affects the overall maximums when compared to the HP BL460 G7 using 16GB DIMMs.  Of course, at $3619 (U.S. List) each, the 16GB DIMMs aren’t cheap either.    In fact, a fully loaded BL460 G7 would cost $43,428 in memory alone – which equals $2,779,392 per 42U rack.  Keep in mind, this is memory costs alone.  The chassis, servers, etc would require a lot more.

If you are trying to get the maximum amount of RAM in a 42U rack, without breaking the bank, check out the maximums using HP’s 2x220c G7 blade servers in a 42U rack:


Cisco B250 M2 (using 8GB DIMMs)
HP BL2x220c G7 (using 16GB DIMMs)
28 servers 128 servers
56 CPUs 256 CPUs
448 cores 1536 cores
10.752TB Max Memory 12.28TB Max Memory

The 16GB DIMMs used in the HP BL2x220c are $999 (U.S. List) so that makes a maxed out BL2x220c G7 node cost $5,994.  Multiplied out for the 128 server nodes you can get in a 42U rack, the HP BL2x220c G7 would cost $767,232 for all of the memory in a 42U rack.  How this compares, in price, to the Cisco UCS B250 M2, I don’t know – Cisco doesn’t have a method of looking up list prices.   

The reality is that it is very unlikely that someone will fill up a rack full of servers with maximum memory, much less large memory DIMM sizes like 32GB.  If there was a sole need for maximum RAM per 42U, there are better ways to achieve than using large memory DIMM sizes, as shown in the examples above. Yes, in the examples above, I used HP but they aren’t necessarily the leaders of max memory per rack.  The other blade server vendors also have large memory solutions.  Dell’s PowerEdge M710HD server (http://bladesmadesimple.com/2010/06/dell-announces-new-blade-servers-m710hd-and-m610x/) can offer 12.28TB of maximum memory in a rack.  IBM’s HX5 (http://bladesmadesimple.com/2010/03/announcing-the-ibm-bladecenter-hx5-blade-server-with-detailed-pics/) that has memory scalability to large amounts of memory per rack using the MAX5

I have to give Cisco credit.  The way they get 384GB RAM is very impressive.  The B250 blade architecture takes 4 x 8GB DIMMs and presents it to the system as a single 32GB DIMM.  Check out this post here on details on how that works:
http://bladesmadesimple.com/2010/01/384gb-ram-in-a-single-blade-server-how-ciscos-making-it-happen/.  I will be curious to know if there are plans for Cisco to create the ability to run 768GB on the B250 M2 with 16GB DIMMs.

Conclusion
Yes, the $8k per 32GB DIMM is hefty.  I don’t know of a lot of users who are buying 16GB DIMMs because the price tag is too large.  The best thing that the 32GB DIMM may bring to the market as Dell, IBM and even Cisco begin selling it is that it will drive down the cost of the 16GB DIMMs making the 8GB DIMMs become “the standard” and possibly eliminate the 4GB DIMMs.