Samsung returns to SLC as the building block for Z-NAND

As part of our visit to Samsung in New York yesterday, the company shed some new light on Z-NAND, its high-performance, low-latency non-volatile storage product. Z-NAND is meant to compete with the 3D Xpoint memory that Intel uses to build its Optane SSDs and non-volatile DIMMs.

Samsung's 983 ZET Z-NAND SSD

According to Samsung, Z-NAND is the name for a single-level-cell implementation of the 3D V-NAND flash that underpins practically every one of its solid-state storage products. Companies have largely abandoned making SLC SSDs in favor of the density and lower costs per gigabyte of multi-level cell (or two-bit-per-cell), triple-level-cell, and even quad-level cell NAND SSDs, but certain customers still need the performance and endurance that a single bit per cell provides.

That demand is part of the reason Intel introduced 3D Xpoint memory and began offering Optane SSDs for the data center. Companies like Aerospike were still purchasing some of the last SLC SSDs available as caching drives for their in-memory database applications, but supplies for those drives ultimately began to dwindle and opened the door for alternative products to come to the fore. The growth of applications that need both high performance and space for large data sets apparently prompted Samsung to begin making SLC NAND for the data center again.

Beyond the implementation of SLC, Samsung said its engineers worked to lower the programming time of Z-NAND to help meet its latency goals for these SSDs. Z-NAND drives also use a large DRAM buffer—1.5 GB in the case of the 983 ZET—that further helps performance. The use of this buffer partially explains the balance between read and write performance that Samsung made for the 983 ZET, however. Read speeds aren't affected by the buffer, but write speeds are hampered by the fact that the drive has to commit whatever is in its DRAM to the underlying flash periodically. Stay tuned for more information on what we learned about Samsung's new data-center SSDs soon.

Comments closed
    • The Egg
    • 1 year ago

    Whatever you think of Optane, it seems to have brought in some healthy competition, as well as making the superior types of NAND available again.

      • chuckula
      • 1 year ago

      Thanks AMD!

      • Neutronbeam
      • 1 year ago

      Eggxactly!

      • blastdoor
      • 1 year ago

      Whatever happened to HP’s plans to change the world with the memristor and The Machine? Was Optane the nail in that coffin?

        • chuckula
        • 1 year ago

        Actually, HP was stopped dead in its tracks when Pink Floyd [url=https://www.youtube.com/watch?v=lt-udg9zQSE<]sued[/url<].

        • Waco
        • 1 year ago

        I can’t go into details…but no, “The Machine” as an idea is not dead.

      • jihadjoe
      • 1 year ago

      AMD dropped the Opteron name too soon!

    • limitedaccess
    • 1 year ago

    What I’m curious about is what the technical challenges would be to allow the amount of cells to user configurable downwards. For example a TLC drive that lets the user toggle it to be MLC or SLC. Crucial’s drives employed a dynamic cache that configured the drive between from TLC or MLC to SLC depending on the amount of free space, it just wasn’t exposed directly to users.

    I can see the reverse direction having obvious hurdles. While it may not be optimal compared to NAND specifically tuned for each case it would allow more flexibility.

      • jihadjoe
      • 1 year ago

      IIRC Samsung’s Evo drives use a portion of the cells as an SLC cache, and this section can move dynamically across the drive so it seems easy enough to use TLC as SLC.

      • Takeshi7
      • 1 year ago

      That would be cool. a single drive could be a 1TB QLC drive, a 768GB TLC drive, a 512GB MLC drive, or a 256GB SLC drive depending on what the user wants.

        • Voldenuit
        • 1 year ago

        God no, I can just see OEMs advertising “up to 1 TB” drives that have atrocious performance and longevity if pushed all the way.

          • Vhalidictes
          • 1 year ago

          That’s a great point, but I’d still like to have the option.

          • limitedaccess
          • 1 year ago

          I don’t see how that is an issue.

          OEMs already aren’t obligated to mention what type of NAND or even SSD model is used in their devices. It’s been like this even with HDDs, a single laptop model can source multiple different drives.

          Even for consumer SSDs many do no disclose the type of NAND. Even something like Crucial’s new BX500 release isn’t forthcoming with the type of NAND is used.

            • chrcoluk
            • 1 year ago

            My observation is the low market targeted devices often ommit the nand type used because its not a selling point, as it turns out the BX500 will use QLC nand, so it is no surprise why that information may not be on marketing specs.

            A bit like how some TN monitors no longer put the display panel type on the spec sheet.

            So if a drive is cheap and doesnt specify the nand type it is likely TLC or QLC.

            I think the idea of allowing a drive to be configured as SLC dynamically is great, but an obvious question which seems to have not been answered is what is the difference between TLC configured as SLC and native SLC. Is the latter superior in terms of endurance?

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