Intel Optane SSD 900P Review: The Fastest, Most Responsive SSD Yet

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What Makes Intel Optane So Special?

As we’ve mentioned, Intel’s Optane products leverage 3D Xpoint memory technology. Optane is Intel’s branding for the entire collection of technologies that make 3D Xpoint memory available to a system. Optane and 3D Xpoint are not interchangeable, however. All of the initial Optane-branded products leverage 3D Xpoint technology, but the two terms are not synonymous. We just want to be clear on that point, because there’s been some confusion out there.

3D Xpoint is being positioned as a revolutionary, non-volatile memory tier that can offer orders of magnitude better performance than NAND and DRAM-like access times, with higher endurance than traditional NAND flash memory and similar capability to scale in density. Our original coverage of the 3D Xpoint announcement is available here if you’d like a quick refresher.
intel optane dc p4800x cpoint

The Optane SSD 900P resembles some of Intel’s previous PCIe-based NVMe storage products, but it is a different sort of animal, from its controller to its storage media, the Optane SSD 900P is not like other NAND-based solid state drives.

The specifications listed on the previous page hint at some of those differences. The drive’s throughput doesn’t seem to be in another class versus other enthusiast-class, NVMe storage products, but note that its 4K IOPS ratings, with fully random and mixed 70/30 workloads, are at low queue depths. The Intel Optane SSD 900P shines at low queue depths, where NAND flash-based storage products tend to falter. The drive’s endurance is also exceptionally high. Optane SSDs are rated for 10 full drive-writes per day, for 5 years, which Intel says is actually a conservative estimate.

Differences Between 3D Xpoint And NAND

Intel Optane drives based on 3D Xpoint media don't require over-provisioning like NAND-based SSDs either. The random write performance of a NAND-based SSD can be improved by increasing the amount of spare storage capacity, because it makes defragmentation more efficient. Since 3D XPoint memory is write-in-place media, there is no defragmentation needed, and therefore no performance to be gained by over-provisioning. Some spare space is used to store ECC and metadata to maintain low error rates throughout the life of the drive, but Optane drives are not over-provisioned in the traditional sense. We should also note that there are significant differences in the 3D XPoint media versus NAND. For example, NAND features lots of extra capacity inside every die for sparing out blocks, as well as managing ECC code words. 3D XPoint memory media does not have or require the extra capacity, so over-provisioning doesn't really apply. With that said, spare capacity beyond the user defined area is leveraged for ECC, firmware, and other maintenance operations.

optane 900p head on

The Intel Optane SSD 900P also handles requests differently than NAND SSDs. For example, when a read request comes into the drive, the normal read write paths are always in hardware, which exploits the low latency performance characteristics of the media. In addition, one read of 4KB is now spread across multiple channels and dies. With NAND-based SSDs today, 4KB reads usually leverage only a single channel. With Optane, the aggregate performance of multiple channels and dies result in higher realized performance. There is also no need to perform defrag operations, so the combination of firmware and write in place media results in consistently low overall latency, in the neighborhood of 10 microseconds, in addition to higher quality of service (QoS).
p4800x performancce 3
This comparison of Intel's enterprise-class SSD DC P3700 versus the Optane SSD DC4800X detailing read latency QoS with mixed workloads, shows just how well Optane behaves, whereas the NAND-based SSD's read latency is all over the map.

latency over time
Optane Solid State Drives also offer much better latency characteristics when under load. What we did here was place the Optane SSD 900P and NAND-based Toshiba OCZ RD400 under a sustained write workload, while testing 4K mixed read / write latency at QD1. When there's no other workload taxing the drives, the Optane SSD 900P already offers significantly lower latency than the RD400. Put the drives under load, however, and the RD400's latency skyrockets, while the Optane drive's latency is only slightly higher.

What this means in the "real world" is that a system packing an Optane SSD will remain more responsive, versus a NAND-based SSD, when there's a heavier, concurrent workloads that may be taxing the storage sub-system.

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