As we speak, we’ll put to good use a few of what we lined final 12 months in our Storage Fundamentals series—particularly, we’ll use
fio to check two competing high-end SATA SSDs.
Every disk has its excessive factors and its low factors, and we’ll cowl each intimately in addition to providing you with some helpful charts to check the 2 immediately.
Samsung 860 Professional 1TB
Samsung’s 860 Professional is a staple of the prosumer business. The 860 Professional marries uncooked, screaming efficiency to stable firmware and excessive write endurance whereas remaining accessible for shoppers and small companies. I’ve personally deployed lots of of the 840 Professional, 850 Professional, and 860 Professional collection of drives to good impact and with no complaints—which is greater than I can say for fairly a number of of Samsung’s opponents.
The 860 Professional is a bit more costly than its child brother, the 860 EVO. That is as a result of the EVO is cheaper—and the specs Samsung chooses to publish make it look as quick—or quicker. The truth may be completely different, relying in your use case. The EVO is a TLC drive with a quick MLC cache, whereas the Professional is fully MLC.
For light-weight shopper workloads that do not burn by means of the EVO’s MLC cache, the EVO actually may be as quick because the Professional. However heavy, sustained write workloads will fall off a cliff—which is actually what the performance-over-time graphs appear to be—as soon as they’ve stuffed the cache and must fall again to writing on to the EVO’s slower TLC major media.
In contrast, the Professional performs reliably and sustainably underneath huge write workloads for so long as you want it to—the whole drive is quick, so there is no cliff to fall from. The Professional additionally has a lot greater write endurance, and for a similar purpose. The TLC-based 860 EVO 1TB is rated for 600TBW (TeraBytes Written), whereas the 860 Professional 1TB we’re testing at the moment is rated for 1,200TBW.
The 1TB 860 Professional we’re testing at the moment is available on Amazon for $200 with Prime transport. (The 2TB model—extra comparable in measurement to the 1.92TB Kingston—runs for $360.)
Kingston DC500M 1.92TB
The Kingston DC500M is one thing that mere shoppers—and even “prosumers”—have not historically gotten to play with fairly often. In contrast to the Samsung, the DC500M is a real information center-grade drive, that includes power-loss safety (PLP) and severe high quality of service (QoS) that helps the DC500M guarantee equity between tons of processes making an attempt to entry the drive on the identical time.
The Kingston can also be rated for even greater write endurance than the Samsung 860 Professional. Kingston designs the DC500M collection for 0.5 Drive Writes Per Day (DWPD). The 960GB model of the DC500M is subsequently rated for a whopping 2278TBW, and the 1.92TB model we’re testing at the moment is rated for 4555TBW—almost double the endurance of the Samsung drives.
For some purpose, all of Kingston’s information middle drives on Amazon are listed in Italian—regardless of being offered by all kinds of American distributors. One of many bigger distributors there offers the 1.92TB DC500M for $347 with Prime transport. If the Italian-language descriptions hassle you, you should buy the drive at Newegg as an alternative—we additionally discovered it listed by a good vendor there for the same $347 price.
I am not going to beat across the bush—on the subject of uncooked efficiency on easy workloads, the Samsung Professional is a quicker drive than the Kingston, and there are not any two methods about it. In nearly each throughput check I threw on the pair, the Samsung 860 Professional ran about 50 to 75 % quicker than the DC500M did.
The distinction between the 2 was most pronounced the place, in my expertise, it tends to matter the least—the 1MiB random learn and write assessments. Whilst you get the most important uncooked numbers on these assessments, there aren’t many functions the place you may actually really feel the distinction between 224MiB/sec and 393MiB/sec. For pretty normal workloads, probably the most seen place for this distinction is in easy file copies from one drive to a different.
Assuming the different drive can sustain with whichever of those you are utilizing, copying a number of GiB of knowledge at 393MiB/sec will clearly full lots quicker than copying the identical information at 224MiB/sec. Most functions aren’t transferring that a lot information that rapidly, although—for many customers, there is not a lot of a seat-of-the pants distinction to be seen right here.
The variations between the drives at smaller blocksizes are much less pronounced, however they’re nonetheless there—and 4KiB random entry is the place the ache lives. For all I simply bought finished telling you that almost all customers will not actually really feel the distinction between a 224MiB/sec learn and a 393MiB/sec learn on the excessive finish, those self same customers will really feel the distinction between 26MiB/sec and 36MiB/sec on the low finish.
For that purpose, I am going to end this part up the identical means I began it—the Samsung Professional is a a lot quicker drive, interval… for comparatively easy asynchronous workloads, at the very least.
Information middle options
The primary graph within the gallery above demonstrates latency, not throughput—and it demonstrates one of many DC500M’s finest options to apparent impact. In that check, we ran 16 simultaneous processes, all clamoring to do 4KiB random writes as quick as they’ll. The y-axis right here is the time to finish every 4KiB write in milliseconds, and the x-axis is the percentile every write falls into.
The DC500M presents considerably higher write latency than the 860 Professional, even all the best way on the left finish of the chart—the quickest 1 % of all 4K writes full in 775 microseconds on the Samsung, versus solely 375 microseconds on the Kingston. However the true story would not occur till across the thirtieth percentile, the place the 860 Professional’s latencies begin rising dramatically—however the DC500M’s latencies don’t.
On the fiftieth percentile—in any other case generally known as the median latency—we’re 36 milliseconds for the Samsung, versus solely 0.5 milliseconds for the Kingston. By the ninety fifth percentile, the Samsung is taking 52ms to finish a write, whereas the Kingston remains to be ending in a mere two milliseconds. The nice QoS we’re seeing right here may not matter a lot on a desktop, nevertheless it’s a killer characteristic for closely loaded database servers or VM hosts.
The second chart exhibits synchronous 4K writes. That is what you get when an software calls
sync()—which mainly tells the pc “I am not doing anything till you affirm you have written that out safely to disk.” The Kingston DC500M has power-loss safety—due to energy capacitors onboard, it might probably safely write out any pending blocks in its DRAM cache, even with none energy from the system it is in.
The Samsung 860 Professional doesn’t have PLP and subsequently cannot assure the security of blocks in its DRAM cache—so sync writes should truly get all the best way to the metallic earlier than the
sync() name can return. Which means the Samsung finally ends up with lower than a tenth the sync throughput of the really information center-grade DC500M.
Lastly, the third chart presents us a distinct have a look at the identical 16-process 4KiB async write we charted the latency on within the first graph. The Samsung is nonetheless a quicker drive, by way of sheer, sustained throughput—however the DC500M’s a lot decrease and extra predictable latency goes a great distance towards demonstrating that top throughput is not all the time the identical factor as seat-of-the-pants “quick.”
It in all probability should not come as a lot of a shock that the way more consumer-oriented Samsung 860 Professional is probably going the only option for many shoppers. What may come as a shock to many Ars readers is simply how inexpensive a real information middle SSD—just like the DC500M—may be, even when purchased in single models.
For the standard desktop-and-gaming workload, it is arduous to say which of those two drives would “really feel” quicker. The Kingston drive will return a lot quicker from probably the most latency-sensitive duties than the Samsung will—however the Samsung has significantly greater uncooked throughput.
Equally, the Kingston presents double the write endurance of the Professional—however most desktop customers will not actually need it. With that mentioned, the write endurance disparity can grow to be extra necessary within the latter years of a drive’s life—efficiency tends to slope downward as an SSD ages, even when nonetheless properly inside its rated endurance.
The throughput distinction between a DC500M and an 860 Professional at a number of hundred TBW could also be significantly smaller than the one you see right here, when the drives are in brand-new situation—and the disparity would nearly actually disappear fully and even reverse itself, as every drive approaches a full petabyte written.
In case you’re constructing a desktop or gaming PC, you’ll be able to’t actually go fallacious with both of those drives—however we might typically give the 860 Professional the nod for its huge throughput. By the point the DC500M’s a lot greater write endurance turns into a consider a typical PC, the whole system ought to hopefully have aged out and been changed lengthy since.
However in the event you’re constructing a giant server working closely loaded databases—or numerous VMs—the DC500M’s information center-grade options, together with power-loss safety, huge write endurance, and glorious QoS, are price severe consideration, regardless of the Samsung’s throughput benefit.