Tag Archives: IBM

Memory choices for the IBM System x3300 M4

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.

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Latency and throughput figures for LRDIMMs emerge

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)

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HyperCloud branding should suggest a better RDIMM

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.

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VLP RDIMMs for virtualization on Blade Servers

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.

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Memory for VMware virtualization servers

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.

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Market opportunity for load reduction

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:

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LRDIMMs future and end-user risk factors

LRDIMMs validated by JEDEC without licensing relevant IP

LRDIMMs are based on a single-sourced “iMB” buffer chipset from Inphi (more on that below).

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What are IBM HCDIMMs and HP HDIMMs ?

Comparing RDIMMs, LRDIMMs and HCDIMMs/HDIMMs

UPDATE: 07/06/2012 – VMware certifies Netlist as sole memory vendor

Adding this as an entry point (or crash course) for folks asking about HCDIMMs and HDIMMs on twitter.

IBM HCDIMMs are Netlist HyperCloud.

HP HDIMMs are Netlist HyperCloud (called “HP Smart Memory HyperCloud”).

HP Smart Memory includes some other diagnostic/error features, and so that feature set has been extended to the HyperCloud and it is therefore also called a “HP Smart Memory”.

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Second take

UPDATE: added 06/24/2012: Invensas on LRDIMM design inferiority vs. HyperCloud

Basically LRDIMMs and DDR4 are both going to be using NLST IP.

This article gives a good introduction:

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First the short take

LRDIMMs is at end-of-life and DDR4 is copying NLST IP.

The new Intel Romley virtualization/data center servers from IBM and HP have support for Netlist (NLST) HyperCloud memory.

This is the memory DDR4 is going to copy (license).

LRDIMMs are already copying it – but have implemented it with asymmetrical lines – leading to latency issues – and inability to deliver 1333MHz at 3 DPC.

With HP Smart Memory HyperCloud – you can get 1333MHz at 3 DPC at 24DIMMs on the 2-processor DL360p and DL380p servers.

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