A Closer Look at Intel's Optane SSD DC P4800X Enterprise SSD Performance
Subject: Storage | February 10, 2017 - 04:22 PM | Allyn Malventano
Tagged: Optane, XPoint, P4800X, 375GB
Over the past few hours, we have seen another Intel Optane SSD leak rise to the surface. While we previously saw a roadmap and specs for a mobile storage accelerator platform, this time we have some specs for an enterprise part:
The specs are certainly impressive. While they don't match the maximum theoretical figures we heard at the initial XPoint announcement, we do see an endurance rating of 30 DWPD (drive writes per day), which is impressive given competing NAND products typically run in the single digits for that same metric. The 12.3 PetaBytes Written (PBW) rating is even more impressive given the capacity point that rating is based on is only 375GB (compare with 2000+ GB of enterprise parts that still do not match that figure).
Now I could rattle off the rest of the performance figures, but those are just numbers, and fortunately we have ways of showing these specs in a more practical manner:
Assuming the P4800X at least meets its stated specifications (very likely given Intel's track record there), and also with the understanding that XPoint products typically reach their maximum IOPS at Queue Depths far below 16, we can compare the theoretical figures for this new Optane part to the measured results from the two most recent NAND-based enterprise launches. To say the random performance makes leaves those parts in the dust is an understatement. 500,000+ IOPS is one thing, but doing so at lower QD's (where actual real-world enterprise usage actually sits) just makes this more of an embarrassment to NAND parts. The added latency of NAND translates to far higher/impractical QD's (256+) to reach their maximum ratings.
Intel research on typical Queue Depths seen in various enterprise workloads. Note that a lower latency device running the same workload will further 'shallow the queue', meaning even lower QD.
Another big deal in the enterprise is QoS. High IOPS and low latency are great, but where the rubber meets the road here is consistency. Enterprise tests measure this in varying degrees of "9's", which exponentially approach 100% of all IO latencies seen during a test run. The plot method used below acts to 'zoom in' on the tail latency of these devices. While a given SSD might have very good average latency and IOPS, it's the outliers that lead to timeouts in time-critical applications, making tail latency an important item to detail.
I've taken some liberties in my approximations below the 99.999% point in these plots. Note that the spec sheet does claim typical latencies "<10us", which falls off to the left of the scale. Not only are the potential latencies great with Optane, the claimed consistency gains are even better. Translating what you see above, the highest percentile latency IOs of the P4800X should be 10x-100x (log scale above) faster than Intel's own SSD DC P3520. The P4800X should also easily beat the Micron 9100 MAX, even despite its IOPS being 5x higher than the P3520 at QD16. These lower latencies also mean we will have to add another decade to the low end of our Latency Percentile plots when we test these new products.
Well, there you have it. The cost/GB will naturally be higher for these new XPoint parts, but the expected performance improvements should make it well worth the additional cost for those who need blistering fast yet persistent storage.