SSDs are about to get a lot faster, thanks to NVMe (Non-Volatile Memory Express) the new industry standard interface for solid-state storage products. It was developed to replace SAS/SATA and fully exploit the advantages of non-volatile memory technologies like NAND flash. Toshiba’s OCZ division just announced their first NVMe-compliant SSDs, the Z-Drive 6000 series. These three models, designed for the enterprise segment of the flash market, are the fastest flash devices OCZ makes with higher availability, lower latency and more consistent performance.
Z-Drive 6000 and 6300 Series
The Z-Drive 6000 SFF series is a 2.5” solid-state drive that connects to the PCIe bus (PCIe Gen3 x4), but using a small form-factor connector, not a card-edge connector as traditional PCIe boards have. It utilizes Toshiba’s A19nm MLC flash and is available with usable capacities of 800GB, 1.6TB and 3.2TB. Designed for read-intensive workloads, the Z-Drive 6000 has sequential/random read performance of up to 2900 MB/s / 700K IOPS and write performance of up to 1900 MB/s / 160K IOPS.
The Z-Drive 6300 SFF series is designed for mixed workload applications, using Toshiba’s A19nm eMLC flash and is available in 800GB, 1.6TB and 3.2TB usable capacities, with a 6.4TB drive available in Q4 2015. It provides up to 2900 MB/s and 700K IOPS, sequential and random read performance, and up to 1400 MB/s and 120K IOPS, write performance.
Both the Z-Drive 6000 and 6300 products have average read latencies of 80 microseconds and write latencies of 25us and 30us respectively. Also announced, but not available until the second half of 2015, is the Z-Drive 6300 AIC series, a half-height, half-length Add-In Card form-factor with usable capacities of up to 6.4TB.
What is NVMe?
The Non-Volatile Memory Express (NVMe) interface was developed specifically for solid-state drives to address the shortcomings of the SATA/SAS interface that was designed for hard disk drives. NVMe connects to the PCIe bus and provides better performance by collapsing the traditional SATA software stack, moving data “closer” to applications and making flash look more like memory than storage. It also manages data writes to minimize flash wear, increasing drive life.
Better SSD Endurance
NVMe software optimizes data placement for flash media, resulting in more effective wear leveling and reduced garbage collection. This means lower, more predictable NAND flash substrate wear due to write and erase cycles, producing SSDs with better overall endurance. The Z-Drive 6000 supports one full drive write per day (DWPD) and the 6300 supports three DWPDs.
Enterprise Features and NVMe Standards
Designed to capitalize on the low latency and parallelism valuable in multi-core virtualized environments, NVMe has scalable queues (up to 64K outstanding commands) and the ability to prioritize commands to support quality of service (QoS) functions. NVMe will also support dual-port capabilities (an upcoming feature for the Z-Drive 6000 series), allowing two host systems to access the same drive or providing redundant connectivity within the same host. The Z-Drive 6000 series also features user selectable power envelopes and temperature throttling for power-sensitive environments.
For OEMs, the NVMe standard promises to simplify integration cycles and speed up new product deliveries. For users the 2.5” SFF form factor is easier to handle than traditional PCIe card-edge connectors, and it’s hot-swappable.
Different workloads and queue depth configurations will produce a range of results, with average latency numbers, like those quoted above, lying somewhere between the extremes. As an enterprise-grade drive, performance consistency is an important characteristic so an important statistic is one that expresses that entire range, not just the average. These are the numbers users can expect to see, even in worse case scenarios. The Z-Drive 6000, in a 4K random test, produced read latencies between 190us and 610us with write latencies between 120us and 16ms, for 99.99% of transactions. According to the company, this was significantly better than the competition for all configurations tested.
NVMe is expected to enable SSDs to realize their full potential, with better performance and drive endurance and an improved SFF connector replacing card-edge PCIe connectors. The Z-Drive 6000 series represent OCZ’s highest performing SSDs to date, but that’s not the whole story. How the vendor implements NVMe is important as well. OCZ has positioned these new drives for the enterprise and not just because they’re faster. Besides speed, enterprise environments need more consistent performance, lower latency and robust features to support better availability and quality of service, characteristics that OCZ’s Z-Drive 6000 drives provide as well.