6 posts • joined 20 May 2012
why can't DELL do the same 25% memory speedup
IBM says that it has an edge over Dell's PowerEdge R820 racker in that it can safely overclock the memory in the System x3750 M4 by 25 per cent compared to Intel's own specifications using either RDIMM or LR-DIMM memory across all four memory channels on the E5-4600 sockets that have three sticks per channel.
Is this something that is preventing DELL from doing this ?
Both IBM and HP are claiming similar 25% speedup on their systems for the RDIMMs.
Installing memory on the HP DL360p and HP DL380p and IBM System x3630 M4
Memory choices for the HP DL360p and DL380p virtualization servers and the similar IBM System x3630 M4 server.
Hope it is simple to understand.
May 24, 2012
Installing memory on 2-socket servers – memory mathematics
May 24, 2012
Memory options for the HP DL360p and DL380p servers – 16GB memory modules
May 24, 2012
Memory options for the HP DL360p and DL380p servers – 32GB memory modules
May 25, 2012
Memory options for the IBM System x3630 M4 server – 16GB memory modules
May 25, 2012
Memory options for the IBM System x3630 M4 server – 32GB memory modules
new thing is HP Smart Memory HyperCloud
For the HP DL360 and DL380, the new thing is:
HP Smart Memory HyperCloud
which is Netlist's HyperCloud memory - whose IP is being copied for DDR4.
LRDIMMs are at end-of-life - long live HyperCloud
I wonder if the author will do an extensive examination of Netlist HyperCloud and what it portends for DDR4 and the future of memory.
HP DL360 and DL380
For the DL360 and DL380, the new thing is the availability of Netlist's HyperCloud 16GB memory modules.
HP Smart Memory HyperCloud offers a "load-reduction" and "rank multiplication" solution.
LRDIMMs offer the same (but is copying Netlist IP and has been very aggressive about it). Inphi has recently experienced a shock with it's challenge of Netlist patent at USPTO having failed. This is negative for the future of LRDIMMs - as Netlist IP has suddenly become unassailable by Inphi in Netlist vs. Inphi.
That is, there could be danger of recall if Inphi is required to destroy all infringing product (like MetaRAM had to do some years back when it conceded in Netlist vs. MetaRAM that they had done so - they conceded and went out of business - incidentally Inphi has hired MetaRAM CEO as "Technical Advisor" so no wonder it is going down the same road).
Inphi is currently the only one making LRDIMM buffer chipsets.
IDTI has prudently postponed LRDIMMs to end of 2012 (skipping the Romley rollout altogether).
Texas Instruments has not been interested in LRDIMMs - possibly because of settlement in Netlist vs. Texas Instruments some years back.
In addition LRDIMMs are end-of-life - as their centralized buffer chipset does not translate to DDR4.
In contrast it is the HyperCloud design which the DDR4 standard is starting to look more and more like.
In addition, LRDIMMs have high latency issues and are not able to outperform the 16GB RDIMMs (2-rank) even at 3 DPC.
For this reason HP/Samsung will not be pushing 16GB LRDIMMs (IDF conference on LRDIMMs).
Currently the 16GB HyperCloud is the only "load-reduction" solution at 16GB at HP. It is being offered as a factory installed option - at the full 3 DPC at 1333MHz on the DL360 and DL380 servers - which are for virtualization (heavy use of memory).
At the 16GB level the need for "load-reduction" is required at 3 DPC. For 1 DPC and 2 DPC, you would be better off with the 16GB RDIMM (2-rank).
16GB LRDIMMs do not appear in HP docs.
When 32GB RDIMMs become available - they will be 4-rank. This will mean "load-reduction" will be required not only at 3 DPC, but also at 2 DPC !! (so not just virtualization but any server requiring 2 DPC will need it). IBM docs list 4-rank memory performing at 1 DPC at 1066MHz and 2 DPC at 800MHz (they won't work at 3 DPC) !!
32GB LRDIMMs can outperform the 32GB RDIMMs (4-rank) for this reason (despite the high latency problems with LRDIMM).
However they do not outperform the 32GB HyperCloud (which will be available mid-2012). IBM lists the 32GB LRDIMMs as "Available later in 2012" - I do not know if 32GB LRDIMMs will appear before 32GB HyperCloud at HP.
32GB LRDIMMs are listed in HP docs.
32GB LRDIMMs cannot deliver 1333MHz at 3 DPC on HP servers. Plus they have the high latency issues.
What to buy
So at 16GB, for 1 DPC and 2 DPC, you would buy 16GB RDIMMs (2-rank) (assuming you are not planning to go to 3 DPC later).
And if you really need 3 DPC now or (upgrade) in the future, you would buy the 16GB HyperCloud.
When 32GB RDIMMs become available - or people want to buy 32GB, you would need 32GB HyperCloud not only at 3 DPC, but also at 2 DPC (and possibly 1 DPC).
32GB HyperCloud will deliver 1333MHz at 1 DPC, 2 DPC and 3 DPC.
And HyperCloud seems to be the design that DDR4 is copying.
Netlist has said HyperCloud will be the first proprietary memory adopted by the industry (if so one would expect JEDEC licensing Netlist IP soon).
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