Riding on the memory bus: Micron brings out 8GB flash DIMM

Rival to Diablo Technologies and SanDisk offerings

Micron UDIMM cards

Micron is launching an 8GB flash DIMM, providing competition for SanDisk and its ULLtraDIMM.

Flash DIMMs mount a flash chip card on a DIMM socket, putting the NAND on the memory bus, which is even faster than the PCIe bus. The idea is to provide an intermediate store or cache between main memory and PCIe flash or SAS-connected flash with disk drives behind that.

The DDR4 NVDIMM product combines an NVDIMM controller, NAND, DRAM and a power source to form a persistent memory sub-system with DRAM-like performance.

Micron's product uses DDR4 DIMMS, like Diablo Technologies' Memory1 product. An earlier Diablo technology was licensed by SanDisk, forming its ULLtraDIMM product, and has been OEM'ed out to Huawei, Lenovo and Supermicro for server use, though without making any visible impact in the market. It's likely that such DDR3 flash DIMMs will be superseded by faster DDR4-based ones.

Flash DIMMs effectively enlarge the storage/memory space close to a server CPU and enable it to run larger datasets in memory, thus making the apps that use them run faster by avoiding slower data access via the PCIe bus and SAS/SATA interfaces out to SSDs and disk.

Micron has provided a comparative view on data access speeds. If a DRAM access takes a second, then a PCIe access will take 22 minutes and a 10K SAS hard disk drive would take 7.6 days.

Suggested use cases for Micron's flash DIMMs are Big Data analytics, storage appliances, RAID cache, in-memory databases and on-line transaction processing.

There will be 3 DDR4 NVDIMM products:

  • 8GB DDR4 NVDIMM w/legacy firmware
    • RDIMM architecture
    • DDR4-2133
    • Single rank x4 configuration
    • In production now
    • Backup power source: PowerGEM or persistent 12V routed to DRAM slot
  • 8GB DDR4 NVDIMM w/JEDEC firmware
    • RDIMM architecture
    • DDR4-2133
    • Single rank x4 configuration
    • Engineering samples available now; Production in early 2016
    • Backup power source: PowerGEM or persistent 12V routed to DRAM slot
  • PowerGEM (ultracapacitor) for 8GB NVDIMM
    • Back-up time: ~40 seconds (the time required for the NVDIMM controller to copy the DRAM content to NAND when power is lost)
    • Back-up power source: tethered ultracapacitor
    • 2.5-inch drive bay form factor

Micron says its Flash DIMMs will provide a bridge to the expected arrival of faster still 3D XPoint DIMMs in 2016, which it is positioning as storage-class memory.

In both cases the main customer will be server OEMs, with the main targets being, we expect, Cisco, Dell, Fujitsu, HP, Hitachi, Huawei, Lenovo and Supermicro, followed by white box server manufacturers like Quanta.

Find out more about the DDR4 NVDIMM at this Micron site, which should come live later today or tomorrow. ®

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