May 18, 2011

Texas Memory Systems Pushes SSD Envelope

Michael Feldman

Enterprise SSD maker Texas Memory Systems (TMS) has been kicking up some dust lately, announcing record-breaking performance results with its RamSan-630 product and launching its latest PCIe flash offering. Specifically, TMS recently put up some rather impressive numbers in two key benchmarks established by the Storage Performance Council (SPC). And then this week, the company introduced its next-generation PCIe flash memory product, the RamSan-70, which incorporates the latest NAND technology from Toshiba.

First to the SPC results. The TMS RamSan-630, a network-attached 3U enclosure that can hold up to 10 TB of flash memory, was able to deliver a record-setting 400,503 IOPS on the SPC-1 benchmark at a price performance of $1.05/IOPS. That beat the SPC competition by a wide margin, specifically, two disk-based IBM systems that approached the TMS gear in total IOPS, but were far behind in price-performance. In the first case, a 6-node IBM System Storage SAN Volume Controller v5.1 hit 380,489 total IOPS, but at $18.83/IOPS, a far cry from the RamSan-630. The less expensive IBM Power 595 with PowerVM delivered 300,993 IOPS, but still at a cost of $10.77/IOPS.

The SPC-1 benchmark is geared for random I/O, so plays into the strength of flash memory, but it’s still a rather grueling test for SSD technology. The workload uses about 60 percent writes and is sustained for eight hours. Also, the device needs to be prefilled with data at the start. That kind of environment is not very SSD-friendly. To get a sense of that, the RamSan-630 SPC-1 result is less than half the peak performance of the 1,000,000 IOPS that TMS claims for the solution.

The SPC-2 benchmark, on the other hand, is geared for sequential I/O workloads like online transaction processing (OLTP), so one wouldn’t expect great results from an SSD setup. (In fact, the RamSan-630 is the first SSD-based system submitted for this SPC benchmark). But the TMS system managed a respectable 8.3 GB/second average over the three SPC-2 workloads: large file processing, large database query and video-on-demand.

That wasn’t as fast as the top-rated IBM System Storage DS8800 system at 9.7 GB/second, but the RamSan-630’s price-performance of $49.37 undercut the $270.38 result for the IBM system rather handily. An HP and Hitachi storage system both delivered about 8.7 GB/second, but at a price-performance of around $187 they were still considerably more expensive that the RamSan box.

According to Jamon Bowen, TMS’s director of sales engineering, the SPC-2 results point to a new use case for enterprise SSD offerings. Whereas before, flash-based systems were only seen as a way to optimize storage IOPS, Bowen says we’re now beginning to see their utility for traditional bandwidth-sensitive workloads, as found in high performance computing and other applications suffering from the data deluge.

Bowen does admit that their SSD box is still going to be about three or four times as expensive as a typical JBOD array built for low cost and MB/second-level bandwidth. But according the him, when you start needing 7 or 8 GB/second for relatively modest-sized storage systems, it’s just cheaper to go the SSD route. “You can now build high bandwidth systems out of SSDs at a lower price than you can disk systems,” he says. “You don’t get the same amount of capacity, but it’s not that far behind.”

Currently there are only a few submissions from SSD vendors to the Storage Performance Council, but at least half of the new members to the group are using flash technology. “I would not be surprised if this becomes the de facto SSD proving ground,” says Bowen.

Besides the network-attached SSD arrays like the RamSan-630, TMS also offers direct-attached flash via its enterprise-class PCIe products like the 450 GB RamSan-20. Those cards are meant to be plugged into workstations and servers for applications that can make use of very fast local storage. For cluster setups, it offers a high performance I/O without the overhead imposed by a network storage solution.

In particular, for large clusters using a shared nothing architecture, the PCIe SSD offer maximum scalability, minimum I/O latency, and the best price-performance. In HPC, these apply to Hadoop-type analytics applications and direct-attached Lustre nodes. In general, any highly parallel application that can partition data along with the computation is ideal for PCIe-based SSDs says Bowen.

This week, the TMS came out with its next-generation PCIe flash card, the RamSan-70. It incorporates Toshiba’s latest 32nm SLC NAND flash chip (which has already been incorporated into the RamSan-630). Compared to the older RamSan-20, the new card delivers about 3 times the performance (330,000 sustained IOPS), twice the usable capacity (900 GB, although a 450 GB version is available too). And because of the smaller NAND geometries, the RamSan-70 takes up half the space of its predecessor and costs about 15 to 20 percent less per GB.

Like many of the latest enterprise-class SSD devices on the market, the RamSan-70 is upping its game in flash longevity and robustness. According to TMS, at 15 percent of the device’s maximum bandwidth (18 TB/day), the RamSan-70 can be expected to last 30 years. Unlike some of its competition, however, all TMS flash management is done with in-house technology. In the case of the RamSan-70, the TMS-developed flash controller logic is implemented with an on-board Virtex-6 FPGA. Bowen says the advantage of such a setup is that the FPGA can be easily reprogrammed — relative to spinning a new ASIC — when new NAND technology is adopted or if new management features are added.

TMS intends to sell the RamSan-70 through an OEM model. In truth, the sales approach is somewhat more loosely defined. According to Bowen, they’ll deal with anyone who can commit to at least 100 cards year. As mentioned before, pricing will be 15 to 20 percent less per GB than the now obsolete 450 GB RamSan-20, which sold for around $18,000. TMS has yet not announced any OEM partners.