Computer components sit on a woodgrain desk.
Enlarge / The Samsung 860 Professional and Kingston DC500M are loaded up within the Storage Sizzling Rod’s hot-swap trays and prepared for battle.

Jim Salter

At this time, we will put to good use a few of what we lined final 12 months in our Storage Fundamentals sequence—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 supplying you with some useful charts to match the 2 instantly.

Samsung 860 Professional 1TB

The Samsung 860 Pro is a well-respected prosumer drive, tending to lead charts in both performance and endurance.
Enlarge / The Samsung 860 Professional is a well-respected prosumer drive, tending to guide charts in each efficiency and endurance.

Samsung

Samsung’s 860 Professional is a staple of the prosumer trade. The 860 Professional marries uncooked, screaming efficiency to strong firmware and excessive write endurance, whereas remaining accessible for customers and small companies. I’ve personally deployed a whole bunch of the 840 Professional, 850 Professional, and 860 Professional sequence of drives to good impact and with no complaints—which is greater than I can say for fairly a couple 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 will be totally different, relying in your use case. The EVO is a TLC drive with a quick MLC cache, whereas the Professional is totally MLC.

For light-weight shopper workloads that do not burn by means of the EVO’s MLC cache, the EVO actually will 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 like—as soon as they’ve stuffed the cache and must fall again to writing on to the EVO’s slower TLC essential media.

In contrast, the Professional performs reliably and sustainably beneath huge write workloads for so long as you want it to—the whole drive is quick, so there is not any cliff to fall from. The Professional additionally has a lot larger write endurance, and for a similar motive. 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 offered on Amazon for $198 with Prime delivery. (The 2TB model—extra comparable in dimension to the 1.92TB Kingston—runs $360.)

Kingston DC500M 1.92TB

Kingston's DC500 series of drives comes in two variants—a less-expensive 500R "read optimized" version, and the heavier duty 500M "mixed workload" version we're testing today.
Enlarge / Kingston’s DC500 sequence of drives is available in two variants—a less-expensive 500R “learn optimized” model, and the heavier obligation 500M “blended workload” model we’re testing at the moment.

Kingston

The Kingston DC500M is one thing that mere customers—and even “prosumers”—have not historically gotten to play with fairly often. In contrast to the Samsung, the DC500M is a real datacenter-grade drive, that includes power-loss safety (PLP) and critical 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 larger write endurance than the Samsung 860 Professional. Kingston designs the DC500M sequence 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 motive, all of Kingston’s knowledge heart drives on Amazon are listed in Italian—regardless of being offered by all kinds of American distributors. One of many bigger distributors there gives the 1.92TB DC500M for $347 with Prime delivery. If the Italian-language descriptions hassle you, you should purchase the drive at Newegg as an alternative—we additionally discovered it listed by a good vendor there, for a similar $347 worth.

Uncooked efficiency

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 no two methods about it. In virtually 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 checks. When you get the largest uncooked numbers on these checks, there aren’t many functions the place you will actually really feel the distinction between 224MiB/sec and 393MiB/sec. For pretty commonplace workloads, essentially 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 so much quicker than copying the identical knowledge at 224MiB/sec. Most functions aren’t transferring that a lot knowledge 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 received achieved telling you that the majority 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 motive, I will end this part up the identical manner I began it—the Samsung Professional is a a lot quicker drive, interval… for comparatively easy asynchronous workloads, at the very least.

Information heart 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 gives 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 does 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 often 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 continues to be ending in a mere two milliseconds. The nice QoS we’re seeing right here may not matter a lot on a desktop, but it surely’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 verify you’ve got written that out safely to disk.” The Kingston DC500M has power-loss safety—due to energy capacitors onboard, it could 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 really get all the best way to the metallic earlier than the sync() name can return. Meaning the Samsung finally ends up with lower than a tenth the sync throughput of the really datacenter-grade DC500M.

Lastly, the third chart gives 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.”

Conclusions

It most likely should not come as a lot of a shock that the way more consumer-oriented Samsung 860 Professional is probably going your best option for many customers. What may come as a shock to many Ars readers is simply how inexpensive a real knowledge heart SSD—just like the DC500M—will be, even when purchased in single models.

For the standard desktop-and-gaming workload, it is onerous to say which of those two drives would “really feel” quicker. The Kingston drive will return a lot quicker from essentially the most latency-sensitive duties than the Samsung does—however the Samsung has significantly larger uncooked throughput.

Equally, the Kingston gives double the write endurance of the Professional—however most desktop customers will not really want it. With that stated, the write endurance disparity can change into extra essential within the latter years of a drive’s life—efficiency tends to slope downward as an SSD ages, even when nonetheless nicely inside its rated endurance.

The throughput distinction between a DC500M and an 860 Professional at a couple 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 virtually definitely disappear totally and even reverse itself, as every drive approaches a full petabyte written.

When you’re constructing a desktop or gaming PC, you possibly can’t actually go improper with both of those drives—however we might usually give the 860 Professional the nod for its huge throughput. By the point the DC500M’s a lot larger write endurance turns into a think about a regular PC, the whole system ought to hopefully have aged out and been changed lengthy since.

However in case you’re constructing an enormous server operating closely loaded databases—or a lot of VMs—the DC500M’s knowledge center-grade options together with power-loss safety, huge write endurance, and wonderful QoS are value critical consideration, regardless of the Samsung’s throughput benefit.

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