The future is now. For years it seems like non-volatile RAM (NVRAM) has been a technology that is just over the horizon. While there have been some isolated use cases where the technology makes sense and is being used, we are now entering, actually we’ve entered, an era where broad adoption of the technology is realistic. To underscore the state of NVRAM, Everspin Technologies is now shipping its first version of its nvNITRO Storage Accelerator which puts NVRAM technology in the hands of data center planners and storage system builders.
The “Right Now” Use Cases for NVRAM
The Storage System Builder Use Case
One of the most obvious use cases for NVRAM right now is for a very high speed write cache or tier where all inbound writes are cached to NVRAM, coalesced and then written to a NAND flash tier. The combination would prolong the life of NAND and make the use of ultra high density drives less of a performance and reliability concern.
There are more than a few storage system vendors that have the technology to use NVRAM as a write cache. They simply need to replace the current tier 1 technology with NVRAM. The nvNITRO should be relatively easy for these vendors to implement because in its drive mode it appears to the system as a NVMe attached drive. The product is even available in a U.2 form factor so it can insert into a PCIe ready drive slot.
nvNITRO is also NVMe over Fabrics (NVMe-F) ready, which means that a storage system builder can develop a scale-out storage solution where data is mirrored in real time between different storage nodes, for increased protection from data loss.
Storage systems vendors are always looking for ways to differentiate themselves, and because flash is the great performance equalizer, it is difficult to accomplish that goal. A system with NVRAM as a front end tier would have a significant write performance advantage as well as a durability advantage.
The Data Center Use Case
IT professionals don’t need to wait for storage system vendors though, they can implement NVRAM solutions like nvNITRO in high transaction environments. Moving logs and indexes to the nvNITRO tier is safe and should deliver a massive increase in performance for the application. Everspin claims 1.5 Million write IOPS per nvNITRO card. The nvNITRO solution can also be used for file system acceleration and metadata caching/buffer. Again, since it just appears as a drive to the operating system, the integration of the technology into the organization’s applications should be relatively seamless.
The initial use cases for NVRAM tend to be as fast storage, the upgrade to flash NAND. Beyond those use cases, though, is using NVRAM as memory. While the type of NVRAM used will vary in performance compared to traditional DRAM technology, it is much closer from a performance perspective than NAND-based flash or even newer technologies like Intel’s 3D-Xpoint. NVRAM is so close to DRAM performance that most applications will not experience any noticeable impact to performance, but now have access to much higher densities of memory capacity.
The other next step for Everspin is higher density cards. Today’s nvNITRO development board is a 1GB card. The company recently announced new 1GB and 2GB cards that are in production and should ship in Q417.
There are several competing NVRAM technologies, Everspin delivers two that are MRAM based; Toggle MRAM and Spin-Tourque MRAM Technology. While Toggle MRAM delivers higher write performance, it is dramatically more expensive since it is harder to reduce the density of the technology. Everspin’s ST-MRAM technology uses the spin torque transfer property, which is the manipulation of the spin of electrons with a polarizing current to establish the desired magnetic state of the free layer to program, or write, the bits in the memory array.
Spin Torque MRAM, or ST-MRAM, provides a significant reduction in switching energy compared to Toggle MRAM which accounts for its greater scalability and density. Everspin uses Perpendicular magnetic tunnel junctions (MTJ) which is in its third generation. They have developed materials and IP stack designs with high perpendicular magnetic anisotropy, which provides long data retention, small cell size, greater density, high endurance and low power.
NVRAM has been more of a “concept car” seeing very limited use cases. An announcement of general availability of a card that IT planners can buy and deploy is a significant step forward. nvNITRO’s drive mode capability makes initial adoption easy and its NVMe support allows IT planners to adopt the technology with confidence.
The key now is for storage system builders to make their designs use the technology. The fact that nvNITRO can plug into a standard U.2 drive bay allows the vendors to offer the solution at minimal risk, simply offer a write performance upgrade option, and swap out two of the NVMe flash drives with nvNITRO drives.