New Data, Storage, and Device Technologies
September 15, 2014, Storage Developer Conference, Santa Clara, CA—Page Tagizad from SanDisk talked about alternate uses and form factors for memory and storage. He also looked at new use cases for flash-type devices.
First, the NVDIMM markets are growing. NVDIMM-N is a mix of DDR3 and NAND to have a persistent memory via writes if the power fails. NVDIMM-F with DDR3 is a block storage alternative to PCIe/SAS and is used for high capacity, low latency SSD block storage through the aggregation of devices on the memory bus. In the future, work by JEDEC and SNIA will address NVDIMM-N2, which is the same configuration as NVDIMM-N with user accessible NAND. The organizations are also considering how to include spin-torque transistor, magnetic RAM, and resistive RAM.
One entrant to the market is a NVDIMM that provides enterprise-class SSD functions from a memory bus. Attaching directly to the memory bus gives the drive access to the high-speed bus lanes and gives very low write latency. The parallel operations and access provide high IOPS and bandwidth, and the controller firmware ensures enterprise endurance.
The internals for the memories are in 19nm MLC flash that can be scaled for performance and capacity by adding more DIMMs. The cards have backup power built in and use a DDR3 protocol configured as a block device through the device drivers. Endurance is rated at 10 full disk writes a day and write latency is less than 5?s.
The applications for this type of hybrid memory are in block devices with low and predictable latency for fast and interactive data analysis. In database apps, the DIMM is configured as a device block or memory extension to increase transactions per second. In a virtualized environment, the block devices help to increase the possible virtual machines and provide a faster response for each vm. Using the DIMMs in empty slots in a blade server enables high-density storage blades. In the future, in-memory compute will use this type of memory for expansion and to reduce analytics response times.
In tests, performance scales at a near-linear rate with additional DIMMs for reads and writes. Write latencies are a few percent of an SSD, due to the direct attach versus the drivers and intervening hardware needed for the SSD. VDI creation and boot storms are mitigated with the flash storage.
