The Samsung PM981 SSD Review (512GB, 1TB): Next Generation Controller And 3D NAND
by Billy Tallis on November 30, 2017 9:02 AM ESTAnandTech Storage Bench - The Destroyer
The Destroyer is an extremely long test replicating the access patterns of very IO-intensive desktop usage. A detailed breakdown can be found in this article. Like real-world usage, the drives do get the occasional break that allows for some background garbage collection and flushing caches, but those idle times are limited to 25ms so that it doesn't take all week to run the test. These AnandTech Storage Bench (ATSB) tests do not involve running the actual applications that generated the workloads, so the scores are relatively insensitive to changes in CPU performance and RAM from our new testbed, but the jump to a newer version of Windows and the newer storage drivers can have an impact.
We quantify performance on this test by reporting the drive's average data throughput, the average latency of the I/O operations, and the total energy used by the drive over the course of the test.
The average data rate of the 1TB Samsung PM981 on The Destroyer is comparable to the 960 EVO 1TB and well ahead of any competing TLC-based drives like the Toshiba XG5. The 512GB PM981 is slower by a typical amount, and still faster than any of the non-Samsung drives of that size.
The 1TB PM981 shows a substantial improvement over the average and 99th percentile latency scores of the 960 EVO, putting it close to the 960 PRO. The 512GB PM981 isn't as impressive, with latency scores that fall behind most MLC-based NVMe SSDs.
The 1TB PM981 sets a new record (among flash-based SSDs) for average read latency on The Destroyer, shaving a few microseconds off the 960 PRO's performance. The average write latency can't quite keep up with the MLC-based 960 PRO that doesn't use SLC write caching. The smaller 512GB PM981 is competitive with most similarly-sized MLC-based drives, but slower than Samsung's 960 PRO.
Samsung's 99th percentile read latency is nothing special, though the PM981 does offer clear improvement over the 960 EVO. The 99th percentile write latency of the 1TB PM981 is excellent and far better than the 1TB 960 EVO. The 512GB PM981 is clearly the fastest TLC-based drive of that size that we've tested, but it doesn't quite match the 99th percentile latency scores of the MLC-based competition.
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romrunning - Thursday, November 30, 2017 - link
@sleeplessclassics - "Today, even TLC can perform better than MLC/SLC just 2-3 generations ago due to better controllers."Well, the MLC-based 950/960 Pro still is basically beating all of the newer TLC drives. Even in SATA, my Sandisk Extreme Pro still beats all of the TLC drives.
sleeplessclassics - Friday, December 1, 2017 - link
@romrunning, well you should have paid more attention in your high school English class.I am comparing present-gen TLC NAND with SLC/MLC that is two generations old.
Of course, current gen 950/960 Pro MLC NAND with Polaris controllers will beat TLC NAND with Polaris controllers.
I suggest you begin one of the simpler ones like Aesop's fables or maybe those illustrated children books will more your level. And while you are at it, try getting an IQ test as well
romrunning - Friday, December 1, 2017 - link
You mad, bro?! ;)Lighten up a little, and act a little more objectively. Try clarifying the original statement or submitting more information to support your point without resorting to childish insults.
For example, I will submit that you would have had to define "generations" and product lines before you put out generic statements like "Today, even TLC can perform better than MLC/SLC just 2-3 generations ago due to better controllers.". It's also hard to compare since the interface can change (like from SATA to NVMe).
For my example, I will say again that my SATA Sandisk Extreme Pro will still beat newer TLC-based SATA drives from Sandisk. Also, I believe older Intel enterprise controllers (like a DC P3700) can still beat a terrible newer drive like the Intel 600p. There are even specialized drives from several "generations" of product lines ago that can beat some of the "newer" TLC-based drives in the same product line-up.
However, obviously this is changing with NVMe-based drives, although it would harder to find a mfg with two "generations" of controllers on NVMe drives. Plus, we're getting into different tech like 3d XPoint, so TLC likely won't be around anymore a number of years in the future.
I personally am looking forward to retail releases of Samsung's Z-NAND-based drives. It will be very interesting to see how they measure up performance-wise to Optane.
treecrab - Thursday, November 30, 2017 - link
Sequential write numbers are off.1TB drive has fooled you - it has HUGE write buffer. Like 50GB huge. You need to check write speed second by second and on a much larger span (100 GB?)
mapesdhs - Thursday, November 30, 2017 - link
Toms posted a review and pointed this out with their sustained tests.Drumsticks - Thursday, November 30, 2017 - link
It feels like we haven't seen new high end drives from Samsung in a while (not that they're really heavily in need given the performance on tap already). It'll be nice to see another round of products coming out of them. Thanks for the review!Side note: Would it be possible to, in future SSD reviews, add those buttons that change the graphs based on capacity for the different storage metrics? Perhaps a button for "All SSDs," "250GB," "500GB," "1TB+" or something. Performance can vary wildly across capacities, and it would be a nice way to sort through all of the 500GB class drives that you've reviewed for example. The only outlier would be Optane since it isn't quite as dominated by the amount of parallel dies you can add.
mapesdhs - Thursday, November 30, 2017 - link
Good idea; it's bizarre how sometimes the 960 EVO looks terrible compared to the 1TB version, and sometimes the other way round. Steady state is particularly bad, it's why I stuck with hunting for 950 Pros instead, which also have their own boot ROM and thus work ok on older mbds.Kastriot - Thursday, November 30, 2017 - link
200$ for 512GB i have intel 530 480GB which i bought on ebay for 80 euros 3 years ago and still working great so ssd prices are insane like memory+gpu+intel cpu-s prices together, dark times for PC desktop owners unless you have dosh :)mapesdhs - Thursday, November 30, 2017 - link
GN has commented on this quite a lot recently, it is indeed a sucky time to build a new PC. Hence why I make the most of used parts (or new ones via normal auction) until the need for something better really is paramount. Bagged another 840 Pro 256GB recently for a good price; pity old models like this are not included in newer product reviews, I bet they'd put newer products to shame. For a while the old Vector was retained in newer reviews, but then it vanished, probably because it just looked too good compared to the latest tech. The same likely applies to the Neutron GTX, Vertex4 and various other models, at least in the SATA world anyway. If one can though, it's better to go NVMe, the SM951 and SM961 are rather good.bcronce - Thursday, November 30, 2017 - link
It looked mostly on par until the "mixed" results. Nice!