The Western Digital WD Blue SN500 SSD Review: Moving The Mainstream To NVMe
by Billy Tallis on April 19, 2019 9:30 AM ESTAnandTech Storage Bench - Light
Our Light storage test has relatively more sequential accesses and lower queue depths than The Destroyer or the Heavy test, and it's by far the shortest test overall. It's based largely on applications that aren't highly dependent on storage performance, so this is a test more of application launch times and file load times. This test can be seen as the sum of all the little delays in daily usage, but with the idle times trimmed to 25ms it takes less than half an hour to run. Details of the Light test can be found here. As with the ATSB Heavy test, this test is run with the drive both freshly erased and empty, and after filling the drive with sequential writes.
The best high-end NVMe drives offer average data rates on the Light test that are twice what the WD Blue SN500 can manage, though the perceived difference in performance for such light workloads is much smaller. When the test is run on a full drive, the fastest drives lose a much larger share of their performance and the SN500 ends up being only a bit slower than the high-end competition.
The average and 99th percentile latencies for the WD Blue SN500 on the Light test are clearly higher than for the top high-end drives, but the good full-drive behavior of the SN500 means it doesn't stick out like some entry-level NVMe drives.
The WD Blue SN500's average write latency shows basically no impact from running the Light test on a full drive, and the impact on average read latency is much smaller than for most drives, especially entry-level NVMe.
The WD Blue SN500 has excellent QoS for both reads and writes on the Light test, even when the test is run on a full drive. Some writes may take a few milliseconds to complete, but the SN500 won't present the user with any noticeable stalls during such a light workload.
The energy usage by the SN500 during the Light test is comparable to that used by the SATA drives, and is lower than what most of the NVMe drives can manage. The fastest drives require about twice the energy to deliver performance boosts that don't really matter to a light workload like this test.
Facebook
Twitter
RSS
50 Comments
View All Comments
DyneCorp - Sunday, April 21, 2019 - link
You got the EX920 512GB on sale. That's not the typical retail price, and the SN500 is already sitting at $65 retail.You understand the price of this drive will go down? As they always do after initial release? And when the prices of NAND skyrocket again, the SN500 will have a major advantage?
For the majority of consumers, the SN500 is a viable option.
airider - Friday, April 19, 2019 - link
This is WD clearing out their inventory while making way for the higher capacity/performance versions coming out shortly. Don't expect to see this product anymore by the end of 2019.flyingpants265 - Saturday, April 20, 2019 - link
Wait, so it's not QLC nand? That's great. It states 300TB write endurance, compared to the 100TB of the 500gb Crucial P1, for the same price. Goodbye, QLC! For now..DyneCorp - Sunday, April 21, 2019 - link
For consumers, the endurance rating matters none. You'll never chew through 100TB of endurance, especially under consumer workloads. The massive SLC cache buffers utilized in the P1 and 660p in addition to smart caching algorithms increase endurance substantially. Also, the DRAM buffer in addition to smart controller firmware effectively mitigate write amplification by several factors. You'll never chew through the endurance of the P1 or the 660p, period.Endurance ratings are meaningless under consumer workloads. SSDs far outlast their given endurance ratings.
flyingpants265 - Wednesday, April 24, 2019 - link
Well, hopefully. Because just to download install one game (hitman 2) requires about 240GB of writes. If I do that 3 times, that's 1% of my drive's life gone.flyingpants265 - Wednesday, April 24, 2019 - link
Uh, 4 times.DyneCorp - Wednesday, April 24, 2019 - link
This is incorrect. 240GB of writes does not equal 240GB of endurance lost, especially if they are sequential writes because:1.) The controller can reduce write amplification by intelligently shifting data around
2.) Sequential writes to the SLC cache increase endurance significantly
3.) Folding blocks from the pSLC cache to QLC actually increases endurance
DyneCorp - Wednesday, April 24, 2019 - link
By the way, this is evidenced by the ADATA SU800. It has a massive dynamic SLC cache buffer and older Micron 32-layer 384-Gbit NAND and still carries the highest endurance rating on the market.willis936 - Saturday, April 20, 2019 - link
I'm surprised there isn't a significant difference in idle power consumption or drive-side efficiency for a DRAMless NVMe drive. This is a pretty nice piece of hardware, regardless of price.DyneCorp - Saturday, April 20, 2019 - link
Thanks for the review, Billy! I really appreciate your work; you always do an excellent job and I appreciate you taking time out of your life to throw these reviews up.Without the DRAM buffer, how do you think write amplification is affected? Obviously endurance is actually quite high (in SU800 territory) and performance is quite high. This is especially interesting considering how small the SLC cache buffer is.
Do you think WD has effectively mitigated negative endurance impact through firmware?