The ever-increasing density of virtual infrastructures, and the need to scale databases larger than ever, is creating an ongoing need for faster storage. And while flash has become the “go to” performance option, there are environments that still need more. Nonvolatile DRAM is the heir apparent, but it often requires customized motherboards to implement, for which widespread availability could be years away. Netlist, pioneer of NVRAM, has introduced a product that is viable for most data centers right now: the EXPRESSvaultTM EV3.
The Flash Problem
While flash has solved many performance problems, it also creates a few. First there is a legitimate concern over flash wear, especially if the environment is write-heavy. There is also a concern about performance. While flash is fast compared to hard disk drives it’s slow when compared to RAM, especially, again, on writes.
But flash does have two compelling advantages over DRAM. First it is less expensive and second, it is nonvolatile. This means that if power is removed from the server, flash does not lose the data it stored; but DRAM does.
The EXPRESSvaultTM EV3
Netlist’s EXPRESSvaultTM EV3 is a nonvolatile implementation of DRAM, where DRAM is protected from power loss by a capacitor, which provides enough power for the data to be copied to flash. These three components are installed on an industry standard PCIe board, making the solution ready to use the day it ships, no motherboard or ROM bios tweaks required. The ExpressVault EV3 comes in 4GB, 8GB and 16GB capacities and backup of RAM can be done in 24 to 96 seconds.
Use Cases for EXPRESSvaultTM EV3
While the above capacity sizes may seem small by today’s flash standards, they are perfectly sized for write caching and the metadata table storage typically used by deduplication and snapshot engines, as well as file systems. Since EXPRESSvaultTM EV3 uses an industry standard PCIe card, storage system integrators and even traditional data centers can adopt the technology as a safe way to accelerate write I/O and metadata table information. At 6.5GB per second write speed and 400K IOPS, bandwidth and latency characteristics of EV3 are order of magnitudes superior to PCIe SSD, and at fraction of the cost.
It seems like the most obvious market for the EXPRESSvaultTM EV3 is as an OEM solution for storage system builders. Cisco and Nimble Storage are already customers. Using EXPRESSvaultTM to store deduplication tables and as a write I/O ‘shock absorber’ would allow all-flash array vendors to extend the performance and life expectancy of their storage systems significantly. This write-based application might even enable the safe and durable use of TLC flash, which would give the vendors the opportunity to adopt such a configuration at a significant price advantage without sacrificing too much performance.
The only roadblock to widespread adoption is the board’s limited compatibility, currently Linux (CentOS / RedHat). Although not an issue for storage system builders, since their products often have Linux at the core, a Linux-only driver might be problematic for data centers. If Netlist would add VMware driver support then it would be easier for software defined storage solutions like VMware’s VSAN, Atlantis’ USX, Maxta, Nutanix and others to support the hardware, allowing users to easily implement a high performance, software defined virtual infrastructure.