Reverting to 3 memory channels per processor – max at 2 DPC
Thanks to Daniel Bowers for clarifying the use of “socket B” Xeon E5-2400 processors in this server.
IBM has announced the x3300 M4 servers – which are 2-socket servers containing 12 DIMM slots.
The 12 DIMM slots suggest these are running at 3 memory channels per processor (as opposed to the 4 memory channel Romley processors seen so far on this blog). And maximum memory capacity is at 2 DPC.
LRDIMMs exhibit 45% worse latency and 36.7% worse throughput at 3 DPC
LRDIMMs (which are a new standard and incompatible with DDR3 RDIMMs) exhibit significant performance impairment at 3 DPC compared to RDIMM-compatible HCDIMMs:
– LRDIMMs have 45% worse latency than HCDIMMs (235ns vs. 161.9ns for HCDIMMs)
– LRDIMMs have 36.7% worse throughput than HCDIMMs (40.4GB/s vs. 63.9GB/s for HCDIMMs)
And this is when HCDIMMs are run at a SLOWED down 1066MHz at 3 DPC (in order to match the lower max achievable speed of the LRDIMMs).
This comparison – at SAME speed – highlights the architectural weaknesses of the LRDIMM design irrespective of the speeds.
When compared at the MAXIMUM achievable speeds (LRDIMMs at 1066MHz at 3 DPC and HCDIMM at 1333MHz at 3 DPC):
– LRDIMMs have approx. 45% worse latency than HCDIMMs (235ns vs. 161.9ns for HCDIMMs)
– LRDIMMs have 40% worse throughput than HCDIMMs (40.4GB/s vs. 68.1GB/s for HCDIMMs)
A reader commented on a problem that end-users face when presented with HyperCloud as a solution – firstly that it is not qualified on the server that THEY use, and secondly that the HyperCloud naming/posturing is not immediately suggestive of an RDIMM-compatible product which may have made them consider it even though it was not qualified on their server.
Why Netlist 16GB VLP RDIMM outperforms the competition
UPDATE: 07/06/2012 – VMware certifies Netlist as sole memory vendor
Netlist claims their 16GB VLP RDIMM has improved performance and reliability/robustness vs. the competitors’ products. And is also cheaper to make.
VMware has certified Netlist 16GB VLP RDIMM memory modules for use with VMware products – it is the only VLP memory product certified by VMware.
VMware certification limited to Netlist HyperCloud and VLP only
Netlist becomes the only memory certified by VMware on it’s virtualization products.
I cannot find a VMware testimonial in favor of LRDIMMs.
Industry estimates of “attach rates”
UPDATE: added 06/19/2012: IDTI comments
UPDATE: added 06/22/2012: analysts on attach rates
UPDATE: added 07/03/2012: Netlist conservative $500M revenue estimate
UPDATE: added 07/03/2012: Netlist conservative $7.5B revenue estimate for 2014
UPDATE: added 07/04/2012: isuppli.com on LRDIMM market
For DDR3, load reduction is essential at:
LRDIMMs validated by JEDEC without licensing relevant IP
LRDIMMs are based on a single-sourced “iMB” buffer chipset from Inphi (more on that below).