Virident PCIe SSD delivers 320,000 read IOPS with 24-year service life

Add Virident to the growing list of companies that have introduced SSDs in the form of PCIe expansion cards to achieve higher storage throughput. The company’s just-introduced tachIOn Drive delivers 200,000 4-kbyte read/write IOPS for 75/25% read/write workloads. The SSD board incorporates a fan-cooled Flash controller and eight Flash modules to create a 200-Gbyte SSD. The Flash modules can be stacked and the board accommodates as many as eight additional Flash modules to create a 400-Gbyte, single-board SSD. These Flash modules can be added or replaced in the field for upgrade or repair purposes. Virident has reportedly qualified flash modules from Samsung, Toshiba, and Micron. According to NetworkWorld, the tachIOn Drive is Virident’s first “broadly launched” product although the company has been developing products for “about” three years.

PCIe drives require an extra software layer to make them look like drives to the OS. The downside of this requirement is that there’s an extra layer of software. However, there are several upsides. The first is raw performance. Peak random read performance for the tachIOn Drive is 320,000 IOPS for 4-kbyte random reads. Although the write performance is not specified in the data sheet, Flash write performance is always slower and the 200,000 IOPS rating for the 75/25% read/write workload suggests that the tachIOn Drive’s write speed is considerably below 200,000 IOPS.

The second advantage of a PCIe storage software driver is that it permits extensive processing of the storage data to optimize the mix and sequence of the read and write streams and to boost reliability and performance of the SSD through wear-leveling and advanced error-correction routines tailored specifically to NAND Flash failure mechanisms. As a result, Virident claims a 24-year lifetime for the tachIOn Drive with 5 terabytes worth of writes per day. The uncorrectable bit-error rate is 10-17. Because some of this management software runs on the server’s host processor, the software driver’s performance only improves as server processors get faster. One disadvantage of this approach, however, is that the drivers run only on x86 processors—for now.