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Why You Should Not Buy DRAMless SSDs
I'm really glad I went for my DRAM-equipped Crucial MX200.
Quote:Unfortunately, DRAMless SSDs also have a sinister side. Updating the map directly on the flash requires small random writes, which takes a bite out of the SSD's endurance. This is a particularly vexing issue with low endurance planar 2D TLC NAND flash. At Computex last June, one SSD vendor told us about an OEM 2D TLC SSD that will burn through the rated endurance in a little over a year. The SSD has to last a year because of the notebook's one-year warranty, but anything beyond a year's worth of use is up to the user to fix. Tactics like that are the driving forces behind putting cheap DRAMless SSDs in $500 notebooks.
There aren't any winners in our roundup today, and we don't hand out participation ribbons. For most of us enthusiasts, we shouldn’t even consider DRAMless SSDs with planar NAND. It's true that the drives are faster than a hard disk drive, but when you lean on them with a slightly elevated workload, they can stall, stutter, and deliver a worse user experience than you would get with a spinning mechanical disk.

Given what vendors told us about the endurance of this emerging category, I'd also be worried about long-term data retention. It's time to worry when a DRAMless controller manufacturer says it's possible to kill a drive in a little over a year. Until recently, SSDs have been add-on components in new notebooks. Some of them are quite expensive with a massive markup over aftermarket components. You might want to factor in the cost of an aftermarket SSD into your overall cost calculations when we start to see $500 notebooks advertised with flash-based storage.

If this sounds like a gloom and doom story so far, you should know that it only gets worse. I've told the variable BOM story more than once. It started with the OCZ Vertex when the company went from 3xnm to 2xnm NAND, and users lost a significant amount of storage space on a 120GB drive. OCZ apologized to users and said it would do more in the future to denote significant changes, which it has. Kingston suffered the same fate with the V300 when it changed from synchronous flash to asynchronous flash, but it has also been clearer about which SSDs have a variable BOM. PNY made the list after selling a drive with the same model number but sending an 8-channel controller to reviewers, and then quickly changing the BOM to a 4-channel controller for retail models.

SanDisk does not advertise the SSD Plus and Z410 as DRAMless products. SanDisk doesn’t really advertise the SSD Plus as anything other than an SSD. The variable BOM is confusing, even for me, and I do this for a living. Claiming an SSD has roughly up to 550 MB/s sequential read and ~440 MB/s sequential write performance is vague, at best. Not only does this drive lack the DRAM cache that would make it an uncompetitive entry-level SSD, but SanDisk also advertises it with nearly identical product specifications as the DRAM-equipped equivalents.

The industry jumped the gun with the DRAMless class of products. The current DRAMless category isn't a viable solution for our readers, and it won't be until we see 3D NAND shipping in volume. 3D NAND will provide enough performance and endurance to transform DRAMless SSDs into a viable category, but Micron's 3D NAND is scarce at best, and Toshiba's is nonexistent on the open market.

OCZ made the right decision and published the T100's endurance specifications. SanDisk published the Z410's endurance specifications, but likely only because it designed the SSD for business users, which often require concrete warranty terms. The SSD Plus not only sells without published endurance or random performance specifications, but it also sells as an MLC-based product at Newegg.

There was a time when DRAMless SSD products were of personal interest to me. When controller manufacturers initially discussed the idea, they portrayed it as a way to increase notebook battery life, reduce power and costs, while at the same time putting an SSD in every computer. Every company expected to have a plentiful distribution of high-endurance 3D NAND flash, and many of these SSD controllers were built with that in mind. That was three years ago. Back then, it’s unlikely that anyone would have thought about selling DRAMless SSDs with low endurance 2D NAND flash to retail customers. The vendors proposed the SSDs for special applications in light-use environments, like signage, point of sale, and industrial applications where a machine reads data back to make a few thousand parts a day but doesn't write more than a few megabytes of data in the process.

The fact that some of these products couldn't even complete an industry standard performance test tells us all we need to know.

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