The Western Digital WD Blue SN500 SSD Review: Moving The Mainstream To NVMe
by Billy Tallis on April 19, 2019 9:30 AM ESTRandom Read Performance
Our first test of random read performance uses very short bursts of operations issued one at a time with no queuing. The drives are given enough idle time between bursts to yield an overall duty cycle of 20%, so thermal throttling is impossible. Each burst consists of a total of 32MB of 4kB random reads, from a 16GB span of the disk. The total data read is 1GB.
This test is confined to a 16GB portion of the drive, but the WD Blue SN500 requires more spatial locality than that to offer its best random read performance, due to its DRAMless design with only a small on-controller buffer and no HMB support. The SN500 ends up as the worst-performing NVMe drive in the bunch and only beats the Toshiba TR200 DRAMless SATA SSD.
Our sustained random read performance is similar to the random read test from our 2015 test suite: queue depths from 1 to 32 are tested, and the average performance and power efficiency across QD1, QD2 and QD4 are reported as the primary scores. Each queue depth is tested for one minute or 32GB of data transferred, whichever is shorter. After each queue depth is tested, the drive is given up to one minute to cool off so that the higher queue depths are unlikely to be affected by accumulated heat build-up. The individual read operations are again 4kB, and cover a 64GB span of the drive.
On the longer random read test, the SN500 still fares poorly, but now that the test span has widened to 64GB, the Toshiba RC100's host memory buffer is also not large enough, and the RC100 falls behind the SN500.
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| Power Efficiency in MB/s/W | Average Power in W | ||||||||
The WD Blue SN500 and Toshiba RC100 draw significantly less power than any of the other NVMe drives during the random read test, with a low-QD average of a bit over 1W. This translates to a good but not great efficiency score for the SN500: the larger drives with much better performance have considerably better efficiency, as does the Samsung 850 EVO that provided 60% better performance without drawing any more power.
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All of the 250GB-class SSDs have limited potential for performance increases at high queue depth compared to higher capacity drives, but the SN500's performance scaling is poor even within its capacity class. Power consumption starts around 1W at QD1 and stays below 2W even at QD32, while the high-end NVMe drives start out above 2W and climb from there.
The random read performance of the WD Blue SN500 never gets out of SATA SSD territory, but the power efficiency is pretty good for the performance it does provide, especially at the higher queue depths.
Random Write Performance
Our test of random write burst performance is structured similarly to the random read burst test, but each burst is only 4MB and the total test length is 128MB. The 4kB random write operations are distributed over a 16GB span of the drive, and the operations are issued one at a time with no queuing.
This burst random write test is short enough that it doesn't come close to filling even the WD Blue SN500's tiny SLC cache, so the great performance of that cache shows through with a score that's competitive against almost any other drive in this capacity class, and only 12% slower than the 1TB WD Black SN750.
As with the sustained random read test, our sustained 4kB random write test runs for up to one minute or 32GB per queue depth, covering a 64GB span of the drive and giving the drive up to 1 minute of idle time between queue depths to allow for write caches to be flushed and for the drive to cool down.
On the longer random write test, the SLC cache on the WD Blue SN500 runs out and its performance falls out of the top tier for 256GB-class drives, but it doesn't fall very far. The SN500 still clearly outperforms the other entry-level NVMe drives we have to compare against.
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| Power Efficiency in MB/s/W | Average Power in W | ||||||||
The power efficiency score for the SN500 during the random write test is a close second place among its capacity class, and is much better than the SATA drives or other entry-level NVMe drives.
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This random write test writes much more data than can fit in the SN500's SLC write cache, so there's no opportunity for performance to bounce around depending on how much cache space was free at the start of each phase of the test. Instead, the SN500's performance and power consumption are very consistent across the entire tested range of queue depths.
The WD Blue SN500's random write performance is pretty close to the limit of what SATA SSDs can achieve, and it gets there while drawing less power than most other drives, but it doesn't set any records.
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Marlin1975 - Friday, April 19, 2019 - link
Actually not bad for one that does not have any large external buffer. That and this is the 250gb model so the 500 should perform a little better as well.Dragonstongue - Friday, April 19, 2019 - link
970 Evo Plus quite stands out for NVME based drives at ~$35 more for same size (just did a price check, amazon, 500gb for this vs 970 evo plus)so while "on paper" this appears great price, is still in very tough ground with ample contendors such as crucial with their p3 ( I believe it was called) countless samsung entries and the like.
for an extra ~$30-$40 seems like "normally" is just not worth it when can do for ones self (such as clock up the slower product, tweaking voltages and the like) when it comes to a "paper" difference and more or less proven real world data this is not all that good a price.
IMO is we take even a high performance HDD as a regular car speed, sata ssd (even highest performance) still is like an expensive supercar speed difference, the next jump would be the nvme based ones which are like top fuel dragsters (at best) but few tracks let them breathe proper and have to deal with engine problems (throttling etc) that normal drive do not have to deal with AND more $$$$$$..
top fuel costs $$$$, do you ALWAYS see this speed, nope, but when you do, is wonderful, when you do not, it becomes a "so why did I pay that much more for little gain and loss in capacity as well as specific motherboards to tap the advantage" etc etc.
kudos to WD, but alas, the margins are so very narrow and expected performance so high is near a non starter for all companies.
I feel the "new standard" for storage should be @500gb for performance and capacity reasons with 1tb prefered (even a 250nvme + whatever size SSD flash in a raid internal no driver required fashion .. I always liked concept of hybrid drives, why not use hybrid memory styles to leverage as well, instead of saddling fast memory with spinning rust, use high speed low endurance flash with lower speed high endurance other flash.
they do pci-e basd, nvme based, sata based etc etc, all have own benefit and detriment. I personally love sata based, leave the motherboard real estate for other things, they should do a further rendition of sata for the hole outs (like me and others whom have a variety of reasons)
if they can patch pci-e to nvme, why not use sta 6 (like current) but tap x2 or x4 pci-e lanes to it as well, let us call it SATA-X, backwarrds compatible with Sta 6g to sata 1 ofc, this would allow some sata or whatever drives up their speed but use a familiar/durable/more widespread form factor.
if all nvme based drives would work in all board or they would not interfere with mobo, not have throttle issues because of dog meta cooling designs (motherboard AND drive maker often enough) it would not be as much an issue, I like sata drive for such reasons, mainly can look "nicer" tend to be much more durable, that much less costly etc etc.
anyways, if WD could do 500 for the price of the 250, that would be most excellent, but as the pricing is, mehhh, overall nice rounded performance with no real shortcomings compared to many others even some of the much more $ drives are not as "rounded" for this they at least did very well at, that much should be said.
like Crucial with MX100, MX500, Samsung with the 800 through 970s (sata and nvme ofc) there are levels that are nice to hit, this SN500 is very much on that edge, up the performance a tough more, reduce price a touch (keep say $40 or better gap between this and the 970 evo plus) then this is that new "leg"
crucial 100/mx500 are more "budget" compared to the "sometimes" faster sammy 8xx/9xx drives, sammy ofc got the speed and endurance markers out there, this "could be" that leg of "rounded performance" just like the mx500 or sammy 8xx/9xx evo ^.^
sonny73n - Saturday, April 20, 2019 - link
Is this a comment or an essay?Hul8 - Saturday, April 20, 2019 - link
"Stream of consciousness" is a style, but usually only applied to fiction.LMonty - Sunday, April 21, 2019 - link
Haha! He just needed to get it out of his system :)Thud2 - Saturday, April 20, 2019 - link
Can you elaborate?Jorgp2 - Sunday, April 21, 2019 - link
Pretty sure this is targeted mostly at OEMsDyneCorp - Wednesday, April 24, 2019 - link
The MX500 is on par with the 860 EVO. SSDs with Micron 64-layer 3D TLC NAND and the SM2262 controller (HP EX920 and ADATA SX8200) absolutely destroy Samsung 9 series NVMe SSDs in certain metrics.The initial price of any product is always high. The SN500 will drop in price. In fact, its not even selling at its suggested retail price from most retailers.
And by the way, comparing SSDs to motor vehicles is ridiculous. Please stop.
jabber - Friday, April 19, 2019 - link
It will do fine for a Steam drive.fazalmajid - Friday, April 19, 2019 - link
I don’t see how such puny capacities can be mainstream, specially when most motherboards or laptops have a limited number of M.2 slots. My minimum would be a 1TB or 2TB Intel 660P.