In 2015, Intel and Micron unveiled 3D XPoint memory, a new competitor to flash memory that promised significantly higher performance and endurance. Several years later, Intel has successfully commercialized 3D XPoint memory in a growing range of Optane products, but other alternative non-volatile memory technologies are still largely stuck in the lab.

To compete against Intel's Optane SSDs, Samsung decided to exercise their lead in 3D NAND flash memory to produce a specialized high-performance variant, which they call Z-NAND. Fittingly, the first SSDs they use it in are branded "Z-SSDs". The first two models to be released were the SZ983 and SZ985, which were both high-end drives specifically for datacenter customers.

Meanwhile, with their major datacenter customers taken care of, Samsung is moving to make more of their enterprise and datacenter storage products available through retail distribution channels instead of just large-volume B2B sales. Spearheading that initiative, the SZ983 is now being sold to retail customers as the Samsung 983 ZET.

Enter the 983 ZET: Going Back To SLC

Samsung originally announced Z-NAND in 2016, a year after 3D XPoint memory was announced and before any Optane products had shipped. Fundamentally, the first generation of Z-NAND is an effort to turn back the clock a bit; to step back from today's modern, high-density, (relatively) high-latency Triple Level Cell (TLC) NAND and back to simpler Single Level Cell (SLC) designs.

SLC designs are relatively straightforward: since they only need to store a single bit of data per cell, the cell only needs to be in one of two voltage states. And this makes them both faster to read and faster to write – sometimes immensely so. The tradeoff is that they offer less density per cell – one-half or one-third as much data as the equivalent MLC or TLC NAND – and therefore a higher cost per bit overall. This has lead to the rapid adoption of MLC and then TLC, which for most use cases is plenty sufficient in terms of performance while also offering great capacity.

However there are markets and use cases where absolute speed (and not capacity) is king, and this is where a SLC-based storage solution can provide much better real-world performance; enough so to justify the higher per-bit cost. And it's this market that Intel and Samsung have been exploiting with their 3D XPoint and Z-NAND products respectively.

Adding an extra wrinkle to all of this is that Samsung's Z-NAND isn't merely SLC NAND; if simply operating existing NAND as SLC was all there is to Z-NAND, then we would also expect Toshiba, WD, SK Hynix to have also delivered their competitors by now. Instead, Samsung has taken additional steps to further improve their SLC-based Z-NAND. We'll go into greater detail on this on the next page, but one of the big changes here was lowering the read and program times of the NAND, which further improves its read/write performance. This is important for Samsung both to give them an edge over the aforementioned competition, but also to ensure Z-NAND is competitive with 3D XPoint, which has proven to be no slouch in this area.

On paper then, Samsung's Z-NAND looks plenty fast for the kinds of workloads and markets Samsung is chasing. Now it comes to Samsung's 983 ZET to deliver on those ambitions.

Samsung 983 ZET Specifications
Capacity 480 GB 960 GB
Controller Samsung Phoenix
Form Factor HHHL PCIe AIC
Interface, Protocol PCIe 3.0 x4 NVMe 1.2b
NAND Flash Samsung 64Gb 48L SLC Z-NAND
Sequential Read 3400 MB/s
Sequential Write 3000 MB/s
4kB Random Read QD32 Throughput 750k IOPS
QD1 99.99% Latency 30 µs
4kB Random Write QD32 Throughput 60k IOPS 75k IOPS
QD1 99.99% Latency 30 µs
Power Consumption Read 8.5 W
Write 9.0 W
Idle 5.5 W
Write Endurance
Drive Writes Per Day
7.4 PB
8.5 DWPD
17.5 PB
10 DWPD
Warranty 5 years
Price $999.99 ($2.08/GB) $2075.85 ($2.16/GB)

The Samsung 983 ZET uses the same Phoenix controller that we are familiar with from their TLC-based 983 DCT and the 970 family of consumer NVMe SSDs. Eight channels makes for a high-end controller in the consumer market, but this is more of an entry-level controller in the datacenter space—the other flash-based SSDs we're comparing against have more powerful 12 or 16 channel controllers.

The 983 ZET is available in just two capacities, both using a PCIe add-in card form factor. Samsung has demonstrated a M.2 Z-SSD and this controller is used in several other M.2 and U.2 drives, but the Z-SSDs are a relatively low-volume product and this retail channel version is even more of a niche product, so the limited range of SKUs makes sense.

The sequential read and write specs for the 983 ZET are typical for high-end NVMe drives with PCIe 3 x4 interfaces, but it's uncommon to see these speeds at such low capacities: the small per-die capacity of Samsung's Z-NAND gives the 480GB 983 DCT as much parallelism to work with as a 2TB TLC drive. The random read performance of 750k IOPS is impressive for a SSD of any capacity, and while it isn't entirely unprecedented, it is significantly higher than the 550k IOPS that Intel's Optane SSD DC P4800X is rated for.

The random write specs bring the first difference in performance between the two capacities of the 983 ZET, and a stark reminder that we're still dealing with some of the limitations of flash memory. The steady-state random write performance is just 60k to 75k IOPS, an order of magnitude lower than the random read performance. Intel's Optane SSDs are only slightly slower for random writes than random reads, so the 983 ZET won't be able to come close to matching Optane performance on workloads that include a significant quantity of random writes.

Write endurance for the 983 ZET also falls short of the bar set by Intel's Optane SSDs, with 8.5 DWPD for the 480GB 983 ZET and 10 DWPD for the 960 GB model, while the Optane SSD debuted with a 30 DWPD rating that has since been increased to 60 DWPD.

The Competition

This review builds on our recent roundup of enterprise SSDs, and follows the same format and test procedures. This review is strictly focused on the use of the 983 ZET as a datacenter SSD, but we will have a follow-up to assess its suitability as an enthusiast class workstation/consumer drive.

Our collection of enterprise and datacenter SSDs is much smaller than our almost comprehensive catalog of consumer SSDs, but we do have drives from several different market segments to compare against. Most of these drives were described in detail in our last enterprise SSD review. The most important competitor is obviously the Intel Optane SSD DC P4800X, Intel's flagship and the drive that Samsung's Z-SSDs were created to compete against.

Sadly unavailable for this review is the Micron P320h, an early PCIe SSD that used 34nm planar SLC NAND and advertised similar random read performance, and better random write performance and endurance. The controller was a 32-channel monster with a PCIe 2.0 x8 host interface that used a proprietary protocol rather than the nascent NVMHCI standard that we now know as NVMe. That controller product line passed from IDT to PMC-Sierra to Microsemi and now Microchip, and its descendants are used in two other drives included in this review, both of which use the 16-channel versions rather than the 32-channel:

  • The Micron 9100 MAX 2.4TB, based on 16nm MLC with excessive overprovisioning: a 4TB raw capacity but only 2.4TB usable.
  • The Memblaze PBlaze5 C900 and D900, both based on Micron 32L TLC NAND. We have a 6.4TB sample of the newer generation PBlaze5 with 64L TLC on the way for a future review.

Z-NAND In Detail & The Test
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  • FunBunny2 - Tuesday, February 19, 2019 - link

    "4th & 5th normal form are touted by academics who never have to work with them"

    well... I have. and the advantage is simple: corrupting data is near impossible, and client code is lean and fast. if simple logic is outside your ability, then may be you should find another line of work. again, let's be smarter than our granddaddies.
    Reply
  • prisonerX - Wednesday, February 20, 2019 - link

    You really don't have a clue about databases, normalized or otherwise. You're entirely FOS. Reply
  • JTBM_real - Thursday, February 21, 2019 - link

    Database servers evolved a lot. High end database servers have the whole database in memory and have scaleable CPU - in practice multiple CPUs. Every processing and storage what is not database can be pushed to other purpose built servers. Purpose built server can be processing or storage heavy as needed.

    If you go to the extremes and cannot build a larger iron you can split your database and have two (or more). This is probably only an issue at google for example.
    Reply
  • Opencg - Tuesday, February 19, 2019 - link

    no price is too high to stop me from instalocking pharah Reply
  • npz - Tuesday, February 19, 2019 - link

    Intel Optane P4800X which it's competing against is $3,420.99 for only 750GB
    https://www.newegg.com/Product/Product.aspx?Item=3...

    and the 1.5TB version is almost twice as much.

    so the 983 ZET 960GB is a relative bargain, haha.
    Reply
  • npz - Tuesday, February 19, 2019 - link

    you also have to remember that since they are going back to SLC instead of trying to stuff as many bits onto the same silicon as possible plus the new technology, of course it's going to be expensive. Reply
  • Samus - Tuesday, February 19, 2019 - link

    Going 'back' to SLC is relatively simple. You don't need to manufacture NAND any different to dictate the voltage states. That is configured at the firmware level. Hence SLC caching occurs on "TLC" NAND.

    The other improvements that dictate Z-NAND are some manufacturing tweaks, but there is nothing stopping Samsung from running the NAND in this drive in MLC or TLC mode, effectively giving you 2-3x the storage capacity. Performance and endurance would obviously take a hit, obviously.

    But the big difference here between THIS SLC and previous SLC is the manufacturing technologies present now since SLC was effectively retired (3D NAND, process node, etc) have all improved tremendously. There was no way to physically fit enough NAND dies running SLC mode on even a PCIe card 10 years ago that would contain 1TB.

    The only other company doing anything like this with modern SLC is SoliData and its mostly for mission critical military applications (SLC mode, inherently running fewer voltage states, tolerates high temperatures better.)
    Reply
  • FunBunny2 - Tuesday, February 19, 2019 - link

    "Going 'back' to SLC is relatively simple. You don't need to manufacture NAND any different to dictate the voltage states. That is configured at the firmware level. Hence SLC caching occurs on "TLC" NAND."

    I seem to recall that some place (here?) described whether the physical cell is constructed the same whatever the xLC. I don't remember the answer. but don't the control structures have to be different (more complicated) for [M/T/Q]LC than SLC? there are [T/Q]LC SSD with SLC cache, yes? the question is whether embedding SLC into a [T/Q]LC SSD behaves just like a native SLC drive. I don't know, but I'd guess it matters.
    Reply
  • Samus - Tuesday, February 19, 2019 - link

    So, I’m not a NAND engineer, but my understanding is NAND cells are optimized for voltage translation, but at the same time NAND l, lets say TLC, isn’t manufactured with a specific SLC ‘zone’ as the controller firmware simply decides to run a portion of the NAND, whatever it may be, in a single voltage state.

    That said, I don’t see why you could just run an entire “TLC” NAND die in SLC mode and reap the benefits at a loss of capacity. It would simply be a reprovisioning.
    Reply
  • Samus - Tuesday, February 19, 2019 - link

    I would say the 900P is more similar to this based on endurance, and the 900P is half the price. Reply

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