Mixed Random Performance

Our test of mixed random reads and writes covers mixes varying from pure reads to pure writes at 10% increments. Each mix is tested for up to 1 minute or 32GB of data transferred. The test is conducted with a queue depth of 4, and is limited to a 64GB span of the drive. In between each mix, the drive is given idle time of up to one minute so that the overall duty cycle is 50%.

Mixed 4kB Random Read/Write

The 1TB Samsung 970 EVO Plus slightly improves on its predecessor's performance on the mixed random IO test, to widen Samsung's lead over other TLC-based drives. The 250GB model fares reasonably well, but is again no match for the oversized SLC cache on the 240GB ADATA SX8200.

Sustained 4kB Mixed Random Read/Write (Power Efficiency)
Power Efficiency in MB/s/W Average Power in W

The WD Black SN750 holds on to another power efficiency win and the Samsung 860 EVO SATA SSD is more or less tied with the 1TB 970 EVO Plus. Most of the 250GB-class drives have substantially lower power efficiency scores due to spending much more time working with a full SLC cache.

The 1TB 970 EVO Plus steadily picks up speed as the workload shifts to be more write heavy. The smaller 250GB model's performance flattens out during the middle half of the test as its smaller SLC write cache starts to get in the way, but toward the very end it too speeds up.

Mixed Sequential Performance

Our test of mixed sequential reads and writes differs from the mixed random I/O test by performing 128kB sequential accesses rather than 4kB accesses at random locations, and the sequential test is conducted at queue depth 1. The range of mixes tested is the same, and the timing and limits on data transfers are also the same as above.

Mixed 128kB Sequential Read/Write

The 970 EVO Plus is a bit faster than the original 970 EVO on the mixed sequential IO test, breaking Samsung's own record. The 250GB model finishes ahead of even the 240GB ADATA SX8200  and is only a few percent slower overall than the 1TB HP EX920.

Sustained 128kB Mixed Sequential Read/Write (Power Efficiency)
Power Efficiency in MB/s/W Average Power in W

The WD Black SN750 and Corsair Force MP510 have the top two power efficiency scores on the mixed sequential IO test, but the Samsung 970 EVO Plus and original 970 EVO are next in line. Both capacities of the 970 EVO Plus require more power than most of their competition, but they put it to good use.

The key to the high overall performance scores from the 970 EVO Plus seems to be that the Samsung drives do not lose performance as quickly when writes are first added to the workload. Many drives have pretty good pure read speed but at 90% or 80% reads they may be only half as fast, while the Samsung 970 EVOs don't see a steep performance drop until around the middle of the test.

Sequential Performance Power Management


View All Comments

  • kgardas - Friday, January 25, 2019 - link

    Thanks for explanation! Actually makes sense indeed. This would also mean that if your workflow is read dominated and you are sensitive on latency than RAID1 of SATA drives may be faster than NVMe. At least if SATA/SAS chip is not a crap. Reply
  • ikjadoon - Tuesday, January 22, 2019 - link

    Even a SATA SSD could pump 4 kB random read numbers up, but it'd require pricey SLC. MLC and TLC both have 2x to 4x slower page reads to register vs SLC.

    latency source: https://www.anandtech.com/show/6337/samsung-ssd-84...

    Still, TLC 4 kB random has improved, but not by "leaps and bounds" like 4K write has. The 970 EVO Plus has 53% faster random 4kB reads (sustained) than the MX 500. And even a 960 PRO has 76% faster 4kB reads (sustained) than the MX500.

    FWIW, random 4K read performance (both burst and sustained) doesn't benefit much of anything from parallelization. https://www.anandtech.com/bench/product/2229?vs=21... The 250 GB and 1 TB 960 EVO have identical 4K read performance, i.e. within 0.75%. Random 4K write and larger page sizes are about 2x faster on the 1 TB model, however.

    Can't vouch for accuracy, but this answer sounds right: https://superuser.com/questions/1168014/nvme-ssd-w...
  • Alistair - Tuesday, January 22, 2019 - link

    The performance is amazing, and I've been buying the 1TB SX8200 for $180 USD before tax. Nothing beats that still. Reply
  • Dark_wizzie - Tuesday, January 22, 2019 - link

    1tb ex820 for $160 after tax and shipping beats it. Reply
  • palindrome - Tuesday, January 22, 2019 - link

    You mean EX920 and it has been as low as $153 recently (before tax). Reply
  • gglaw - Tuesday, January 22, 2019 - link

    Not too long ago it was $135 twice with the Ebay and Rakuten 15% coupons. $155 range seems almost every other week now and frequent enough I'd even consider it the typical selling price. (Very few people who follow tech would actually pay $180 for it). Can't beat this for consumer use with the small performance differences with current gen drives. When the EX950 and SX8200 Pro phase it out and drop to the same price points, they'll replace it as best consumer deals so I don't see the new Samsung or WD having a place in my line-up.

    If for some purpose I can find a use for something more expensive, it'd have to be the next gen 970 Pro (Plus?) if it's a major upgrade.
  • ** A - R ** - Wednesday, January 23, 2019 - link

    Billy, Specs in the official site mentions MLC, here I see it's TLC ! ?
    Could You please verify it.
  • olafgarten - Wednesday, January 23, 2019 - link

    It says 3 bit MLC, meaning TLC. Reply
  • mortenge - Wednesday, January 23, 2019 - link

    Why do you bring Optain into the mix and not the 970 PRO, when all we care about is EVO vs PRO? Reply
  • alfatekpt - Wednesday, January 23, 2019 - link

    The review should include 970 EVO 250GB numbers for comparison. Reply

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