Solved: 16 GB DIMMs on UCS

dani_bosch · ‎02-10-2011

Hello all,

I've just seen Cisco 16 GB DIMMs in Netfomx...I was expecting them to be twice the price as 8 GB DIMMs (price per GB) but they are surprisingly cheaper than this...roughly 50% more expensive...

What is Cisco's advise on using this DIMM's?? If they can be positioned everywhere, that's pretty much the end of Extended Memory's advantage...am i wrong??

Thanks a lot,

jiding · ‎02-11-2011

Dani,

I am not sure where you get the 16GB price. Based on what I am seeing (and confirmed with our UCS product managers), the 16GB DIMM price listed on Netformx is exactly the twice the 8GB DIMM price.

Currently the quad-rank 16GB DIMM price is twice the price of the 8GB DIMMs. But the quad-rank DIMMs will operate at 800MT/s speed when you populate 2-DIMMS-per-Channel (2DPC) pattern in x5500/x5600 based two socket servers. That means a 12 x 16GB = 192GB server will have DIMMs operating at 800MT/s, compared to Cisco UCS B200/C250 servers with 48 x 8GB = 394GB memory operating at 1333MT/s.

The dual-rank 16GB DIMMs is still very expensive. Last time we checked, some of the system vendors list their price on the web over $3300 per piece. This price may go down gradually, but it will take some time to be twice the 8GB DIMM price. Even for that, 2DPC pattern wil still be 12 x 16GB =192GB capacity, only half of the 394GB capacity that UCS B250/C250 is able to achieve. If a x5500/x5600 server supports 3DPC, then all the dual-rank 16GB DIMMs will be operating at 800MT/s with a capacity of 18 x 16GB = 288GB (< 384GB)

Hence, Cisco extended memory technology still have an edge of using lower density and lower cost DIMMs to achieve higher capacity and higher performance.

Jason Ding

Cisco SAVBU

View solution in original post

jiding · ‎02-11-2011

Dani,

I am not sure where you get the 16GB price. Based on what I am seeing (and confirmed with our UCS product managers), the 16GB DIMM price listed on Netformx is exactly the twice the 8GB DIMM price.

Currently the quad-rank 16GB DIMM price is twice the price of the 8GB DIMMs. But the quad-rank DIMMs will operate at 800MT/s speed when you populate 2-DIMMS-per-Channel (2DPC) pattern in x5500/x5600 based two socket servers. That means a 12 x 16GB = 192GB server will have DIMMs operating at 800MT/s, compared to Cisco UCS B200/C250 servers with 48 x 8GB = 394GB memory operating at 1333MT/s.

The dual-rank 16GB DIMMs is still very expensive. Last time we checked, some of the system vendors list their price on the web over $3300 per piece. This price may go down gradually, but it will take some time to be twice the 8GB DIMM price. Even for that, 2DPC pattern wil still be 12 x 16GB =192GB capacity, only half of the 394GB capacity that UCS B250/C250 is able to achieve. If a x5500/x5600 server supports 3DPC, then all the dual-rank 16GB DIMMs will be operating at 800MT/s with a capacity of 18 x 16GB = 288GB (< 384GB)

Hence, Cisco extended memory technology still have an edge of using lower density and lower cost DIMMs to achieve higher capacity and higher performance.

Jason Ding

Cisco SAVBU

dani_bosch · ‎03-02-2011

Well actually the 16 GB DIMMs are exactly 22% more expensive than 8 GB DIMMs (price per GB), but I presume that is because the Low Voltage feature introduces this price premium.

When will Cisco sell the dual rank 16 GB DIMM's? Why not to do it now?

Thanks a lot Jianxun.