Jim Salter
Not too long ago, main SSD distributors Essential and Western Digital have each been caught swapping out TLC NAND of their client SSDs for cheaper however a lot lower-performance, lower-endurance QLC NAND. Samsung seems to be becoming a member of them within the part-swapping nook of disgrace right this moment, due to Chinese language Youtuber 潮玩客, who documented a brand new model of the Samsung 970 Evo Plus utilizing an inferior drive controller.
Though the consumer-facing mannequin variety of the drives didn’t change—it was a 970 Evo Plus final 12 months, and it is nonetheless a 970 Evo Plus now—the producer half quantity did. Sadly, the producer half quantity is not seen on the field the SSD is available in—so far as we have been in a position to decide, it is solely proven on a small label on the drive itself.
Falling off the write cliff
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This CrystalDiskMark take a look at makes the newer, inferior drive look quicker than the unique in most exams—however discover the very small 1GiB take a look at dimension. This take a look at is not escaping the SLC write cache!
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On this HD Tune Professional take a look at, we are able to see the “write cliff” impact on each drives because the SLC cache is exhausted—however the distinction is not HD Tune Professional vs CrystalDiskMark, it is 1GiB take a look at vs 200GiB take a look at.
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We will additionally see the “write cliff” impact in a easy massive file copy—when the write cache is exhausted, the brand new drive is way slower than the outdated.
We examined the 970 Evo Plus (alongside the 980, and the older 970 Professional) in March, clocking it at write speeds of 1,600+ MiB/sec on 1MiB workloads. Our benchmarking was executed with he outdated model, half quantity MZVLB1T0HBLR. The newer model—half quantity MZVL21T0HBLU—is significantly slower. In response to 潮玩客’s take a look at outcomes, the newer model solely manages 830MiB/sec—half the efficiency of the unique.
It appears probably that Samsung, like Western Digital, hoped the half swap would go unnoticed as a result of the top consequence was “adequate.” Underneath most gentle utilization workloads, a person may by no means discover the brand new half quantity’s decrease efficiency—as a result of like practically all trendy SSDs, the 970 Evo Plus incorporates a SLC write cache that is a lot quicker than its fundamental storage NAND, and the brand new half’s efficiency drop does not develop into obvious till after the cache is exhausted.
潮玩客 first examined the outdated and new 970 Evo Plus drives utilizing CrystalDiskMark, and the drives appeared near-identical. However that is as a result of CrystalDiskMark by default makes use of a really small 1GiB take a look at dimension, which clearly isn’t sufficient to exhaust both drive’s write cache. (We at Ars continuously use CrystalDiskMark—however we choose bigger take a look at sizes, for exactly this cause.)
In longer exams, each drives lower sharply in efficiency as cache fills, which is anticipated. However whereas the older drive retains practically two-thirds of its unique efficiency, the newer model craters to lower than a 3rd. We will see this impact not solely in synthetic benchmarks, but in addition in massive file copies, as seen in 潮玩客’s later exams.
The controller is the offender
One of the best information for impacted 970 Evo Plus house owners is that they need to “solely” be taking a large efficiency hit, with no corresponding lower in write endurance. That is as a result of in contrast to Essential and Western Digital’s part-swaps, Samsung did not drop from TLC flash to QLC—it simply swapped out the controller.
The older, higher-performing drives have a Phoenix controller and the newer, lower-performing drives use one made by Elpis. Tom’s {Hardware} points out that Samsung is already recognized to be dealing with controller shortages, with its personal Texa controller factories having been idle since February.
Though Samsung’s half swap will probably have a decrease direct buyer influence than Western Digital’s or Essential’s, it is nonetheless disappointing that the corporate is pulling this with out informing the general public. Finally, we’re speaking about two variations of the identical mannequin with considerably completely different elements and a drastic discount in efficiency, with little or no method for a buyer to identify the distinction—and pandemic or no pandemic, that is simply not okay.
潮玩客’s unique video is right here—however you will not get probably the most out of it except your Mandarin is considerably higher than mine.
Itemizing picture by Samsung
