DIMM wars in SSD servers

how significant is Diablo's Memory1
for the enterprise data ecosystem?

• memory caches on the CPU chip,

• caches external to the CPU chips,

• real DRAM (the kind of modules you see plugged into the motherboard) and

• emulated DRAM (the virtual memory which gets swapped in and out of HDDs and SSDs).

• DRAM latency at the hardware level (as seen by local CPUs) is worse than it was in the year 2000.
  
  There are many reasons for this - the chief being that enterprise memory systems have been optimized for density and cost rather than speed. And the growing complexity of multi processor cache designs means that worse case latencies are much longer than you might think. See more here - latency loving reasons for fading out DRAM in the virtual memory slider mix.

• DRAM latency - as seen by applications - is really the "virtual memory" latency which arises from the cumulative impact of several different system behaviors. These include upstream storage, cache properties and the software stacks. In effect all legacy applications have been "trained" during the past decade or so to operate with a DRAM latency which has statistical latency properties which are good enough rather than guaranteed.
  
  During the first 5 years or so of the PCIe SSD market it became clear that making storage latency faster (than the HDD models assumed in rotating storage architecture) could enable trade offs in memory size in which DRAM could be replaced by flash within certain operating bands and achieve similar application performance at much lower operating costs.

• software which remaps big RAM memory into flash SSDs.
  
  For example:- SanDisk's ZetaScale. This operates with a wide range of SSD interfaces - so users have a lot of freedom to optimize their latency / cost profile. At the extreme limits Memory1 may be faster in latency terms than most PCIe SSDs - but my guess is that some kind of future ioDrive like product (possibly optimized to strip away non volatility) would give very similar performance.
  
  Other SSD software companies which until recently have been in stealth mode are also coming into the latency lowering flash market.

• in-situ processing - combined with PCIe SSD platform.
  
  Companies which have been talking about this since last year include:- NxGn Data, Memblaze and others. And earlier this year further validation of the concept came from researchers at MIT who showed that flash can come close to RAM rich server performance by using clunky app-specific FPGAs combined with flash.

• Netlist? - This company which was embroiled for over a year in legal actions aimed at Diablo's first product - the MCS SSDs - is one of several in the hybrid DIMM market which might make a future pitch in this market. Having said that there's a world of difference between these DIMM compatible RAM SSDs and Memory1 - where the RAM which is used is actually in another socket supplied by someone else. Other companies in this category include Micron. But due to the market risks of shooting its other products in the foot I think Micron will prefer to position its response to this application in different ways first (with higher priced solutions).

• Already mentioned above - high density 3D PCM from Intel and Micron. Details at the present time are sketchy. But it's reasonable to assume this will initially be offered at much higher cost than flash solutions - because it's a new technology and unlike Memory1 - a key characteristic it offers is non volatility.

• 1999 to 2007 - the dominant focus and center of gravity was FC SAN SSD accelerators.
  
  That was the pragmatic place for SSD accelerator leaders to focus - because it was relatively easy to integrate in legacy installations which had been conceived by users with pre-SSD era thinking.
  
  Furthermore FC SAN users - as a market - were representatitive of a user base which was focused on performance and which had more money and technical resources to engineer systems which were performance oriented than other segments in the storage market.
  
  That period was especially complex for users because it overlapped with the transition within the enterprise SSD market from dominance by RAM SSDs to flash based SSDs - which introduced many technology signals to the market which were easily capable of being misinterpreted by vendors and users alike - due to the fact that in the previous 2 decades there had been relatively few disruptive technology changes in the enterprise server market.
  
  And further complicating factors were that FC SAN SSD accelerators were being marketed by small vendors directly to SSD illiterate end users and bypassing the existing hostile distribution channels of the encumbant SSD ignorant server and storage heavyweights.
  
  And all this was being done before the existance of an SSD software market - which would later automate and simplify SSD integration and therefore accelerate sales.

• 2007 to 2014 - the dominant focus and center of gravity was PCIe SSD accelerators.
  
  It was the rapid and domino effect-like adoption of 3rd party PCIe SSD accelerators by every mainstream server manufacturer - which had been predicted years earlier as an inevitable consequence of CPU-SSD equivalency - which changed the way that SSDs were perceived from being an alienlike technology promoted by industry outsiders to being a necessary option which was expected to be supported inside every new server product line.
  
  What we've been seeing in the enterprise PCIe SSD market in recent years is that most vendors are focusing on making these products more affordable rather than trying to push the limits of performance.
  
  In the performance enhancement region of the market - the emerging changes have been towards getting better application performance by better integration with software rather than speedier flash or interface speeds.
  
  These efforts include:- application optimized stacks, incremental standards such as NVMe, 3rd generation controller architecture (multi-level partitioned flash movements) and in-situ processing.

• 2014 - 2018 - the new dominant focus and center of gravity in large memory systems will be DIMM wars - which revisit long held assumptions such as - what is memory? - where's the best place for it to go? - and how much memory of each latency is best to have in each location? (Given that multiple distinct memory and storage latencies have found viable and enduring economic and architectural product classication silos already.)
  
  These questions are being asked due to growing confidence from the SSD market experience that application architectures and the design of data processing engines are not (as once seemed) set in stone. They can be changed - if it makes sense from a business perspective. And although the investment costs are huge - the enterprise market has already learned to adapt to many changes caused by flash and to many adptations within the evolving flash architecture experience itself. So that opens the door for other memory types too.
  
  The territory for future DIMM wars includes already established emerging technologies (memory channel SSDs, NV DIMMs / hybrid DIMMs) but also new products such as ultra high capacity DIMMs, nonflash NVDIMMs, memory fabric expansion (by PCIe and IB) and probably big memory fabricated onboard CPU chips (as an alternative to simply adding more DRAM cache or more cores).
  
  A big incentive for server makers to engage in DIMM SSD wars is that integration with motherboard resources and firmware promises better lock-in at the customer level because traditionally end users have been less willing to exercise their freedoms to choose 3rd party competitive suppliers for DIMM components.
  
  It may be that the DIMM SSD could become a stickier component for server makers than PCIe SSDs. It's certainly the case that many of the early generations of DIMM enhanced SSD products have required special cables or power or bios customizations by server makers to support their operation.

• the fastest SSDs

• rethinking DRAM

• RAM in an SSD context

• why buy SSDs? - user value propositions