The Western Digital Ultrastar® DC SN640 NVMe SSD is a mainstream NVMeTM SSD targeting broad deployment as boot, caching, or primary storage in data center IT and cloud environments. It is a popular and efficient storage solution for enterprise-scale tasks that require consistent quality of service and low latency for mixed random read/write workloads commonly generated by applications such as virtualization, OLTP, NoSQL, web servers, file servers, and mail servers.

However, when a fault-tolerant solution is needed, traditional RAIDs on NVMe are unable to deliver full drive performance levels, which can be a problem for data-driven businesses.

The solution is to combine the Ultrastar DC SN640 SSDs with RAIDIX ERA software. Purpose-built for NVMe, with lockless datapath and I/O parallelization, RAIDIX ERA creates a highly performant software RAID from NVMe drives, putting out up to 97% of their raw performance. 

Testing performance

This impressive boost was seen during benchmarking tests performed by Western Digital engineers. When using 8 NVMe drives, 3,890,000 IOps for random read performance (RAID 5, 4k block), 454,000 IOps for random write performance (RAID 5, 4k block), and 1,260,000 IOps for random mixed performance (RAID 5, 4k block, 70/20 r/w) were reached.


These numbers are a big step up from the performance of traditional RAIDs. The tests also proved that RAIDIX ERA increases sequential read performance (RAID 5, 128k block), allowing it to reach 18.5 GB/s and boosts sequential write performance up to 11.5 GB/s.

Additional testing was also carried out to push the limits and see how RAIDIX ERA would perform in combination with RAID 5 volume consisting of twenty Ultrastar DC SN640 drives. During this testing, figures of 1,250,000 IOPS on random write performance were obtained, while random read performance reached 10,200,000 steady-state IOPS.

The Ultrastar DC SN640 NVMe drives also demonstrated their reliability as they were subjected to heavy workloads, sometimes exceeding ten full drive writes per day, over the course of several weeks, demonstrating stable performance with good thermal results. 

Testing parameters

It should be noted that while there is no single industry-accepted methodology for measuring the performance of multiple SSDs in a RAID configuration, Western Digital engineers chose to follow SNIA PTS, which is a standard for single-drive performance evaluation. 

In addition to the tests outlined above, RAIDIX’s own tests showed that ERA reduces latency to the limit of 0.5 ms. Even in degraded mode, performance remains high: for RAID 50, the penalty does not exceed 25%. Other RAIDIX ERA features are a wide range of supported RAID levels (RAID 0, 1, 5, 6, 7.3, 10, 50, 60, 70), POSIX API support, and surely being lightweight, as it only uses less than 20% CPU under the maximum array load, and no more than 4GB RAM is needed for full-featured work.

Such performance boosts overall efficiency and slashes business costs: for example, RAID 5 performance with 8 NVMe under RAIDIX ERA is comparable with RAID 10 performance with 16 NVMe drives.

To get a FREE RAIDIX ERA license for Western Digital Ultrastar SN640 drives, visit the RAIDIX website. The EU holders of the ERA license will also get access to an offer from Exertis Hammer with special prices for Western Digital Ultrastar SN640 SSDs and server platforms powered by Intel and AMD.

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