3D XPoint mem­ory hits the main­stream.

APC Australia - - Contents - Jeremy Laird

Ten times the data den­sity, 1,000 times faster, 1,000 times bet­ter en­durance. All of this and more In­tel claimed three years ago for its rev­o­lu­tion­ary 3D XPoint non-volatile mem­ory tech, now branded Optane. Those claims were made in com­par­i­son to the non­volatile mem­ory tech that dom­i­nates the stor­age in­dus­try, namely NAND flash mem­ory.

Now we have our hands on In­tel’s first more-or-less main­stream SSD for PCs based on 3D XPoint, the Optane SSD 800p. But what’s this? Se­quen­tial reads of 1,450MB/s? Writes of just 640MB/s? And check out the IOPS, too. In­tel rates its new Optane drive at just 250K read IOPS and 140K for writes. Far from be­ing 1,000 times faster than a NAND SSD, all those fig­ures are sig­nif­i­cantly slower. What’s go­ing on? The short an­swer is that it’s com­pli­cated. At launch, it’s only avail­able in two con­fig­u­ra­tions: 58GB and 118GB. Launch pricing is $179 for the smaller drive and $289 for the 118GB drive tested here (which for­mats down to 110GB). Ex­pen­sive, small and slow, you may be think­ing. In many of our bench­marks, the 800p is un­re­mark­able by con­ven­tional SSD stan­dards, and a ma­jor let­down given the hype that ini­tially ac­com­pa­nied 3D XPoint. Se­quen­tial through­put is pretty much in line with In­tel’s claims, and thus miles off the fastest NAND-based SSDs.

Granted, In­tel has gone with a dual-lane PCI Ex­press in­ter­face for the 800p, which puts a cap on peak trans­fer per­for­mance com­pared to high-end NAND drives with quad-lane in­ter­faces, but that’s clearly not what is hold­ing back the 800p’s se­quen­tial write per­for­mance, which clocks in at a max­i­mum of 650MB/s in ATTO Disk Bench­mark. That’s barely any faster than a SATA SSD.

How­ever, Crys­talDisk Mark’s 4K ran­dom ac­cess met­rics hint at the 800p’s greater po­ten­tial. The 800p reg­is­ters 229MB/s for reads and 176MB/s for writes. Those fig­ures are much faster than the cur­rent gold stan­dard of NAND SSDs — the Sam­sung 960 Pro — can muster. Broadly speak­ing, then, the fo­cus for this drive is on low la­tency and low queue-depth per­for­mance, not peak through­put.

In­tel says that the 800p is 4–5 times faster to re­spond at short queue depths of one and two com­pared to a NAND-based SSD. (It’s at much deeper queue depths of up to 32 where those NAND drives de­liver their fastest 4K ran­dom ac­cess per­for­mance.) What’s more, In­tel reck­ons it’s those shorter queue depths that most de­ter­mine the per­for­mance of typ­i­cal client PC work­loads. In­tel also says per­for­mance is main­tained re­gard­less of how full the drive is, and rates the 800p for 365TB of writes, which is in­cred­i­bly high for such a small drive.

All told, the new In­tel Optane SSD 800p is a bit of a mixed bag. This is, very likely, the most re­spon­sive main­stream SSD you can buy. It’s also quite pos­si­bly the most ro­bust. But it’s not the fastest. 3D XPoint could well still be the fu­ture of PC stor­age, but for now, it feels like a beta tech­nol­ogy.


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