Final Words & Conclusion

Final Words & Conclusion

The Team Group Cardea Zero Z44Q's synthetic figures are interesting. Trace testing however dictates that this SSD performs more commonly than peak values will make you believe. Impressive are the random I/O operations (both read and write), as well as the sequential transfers. If you need a lot of fast storage then the Z440Q ticks a lot of boxes. The comprises however might not outweigh the benefits. First off, at 16 Cents per GB the SSD is too expensive. QLC was introduced into the market to be a cheap offering for a lot of storage. As such, we do not deem QLC SSDs viable enough until it drops under 10 cents per GB.  Why do I say that? Well, QLC has two challenges. The first being endurance issues, the second is RAW write performance. This 4TB SSD that we just tested, can write 800 TB before cells start to die off and map themselves out. Realistically though, that's a huge value for modern age PCs. However, to place it into a rather solid-state of relativeness, this SSD in a 1 TB version would thus have a 200 TB lifespan. So the Achilles heel is endurance, but that's why they make these big volume SSDs, to compensate are more cells means more endurance. We'll talk more about this in a separate chapter though. Nice to see is that Team Group includes two cooling options with the drive, one for when you have enough space (desktop PC) and a graphene sticker for when you do not (laptop). That graphene sticker actually does help a little, and when you apply cooling we still measure proper values. And you will need cooling, it's not the Phison controller that will run that hot, but the NAND ICs. Without cooling, a bit of thermal throttling will be noticeable under massive workloads. In that case writes hover at 2.5 GB/s and 2 GB/s for the uncooled drive. You can however write multiple minutes before throttling occurs.  

Endurance

So for normal PC usage, gaming and mass (cold) storage like your movies and game library we have very little to complain about really. However any potential end-users (you) have to face a bit of a fright, it's the same scare that the move from MLC towards TLC NAND invoked, that's lifespan aka endurance. It's not different for me, currently based on the minor price differences I'd be happy to spend 20 bucks more for a TLC drive. The reality is however that when you math things out, the picture does change. Allow me to throw an example at you: if we focus on the submitted and reviewed 4 TB version, with its rated 800 TBW you would need to completely write the SSD 200 times x 4TB before the NAND cells start to die. Let's normalize that to a bit more understandable proportions if you write 50 GB per day each day of the year (which really is a lot!) x 365 / 1000 = 18.25 TB written per year. So in that scenario that's almost 44 years of lifespan and 22 years for the 2TB model. These are the metrics we're talking about. So in terms of lifespan and endurance, for a regular PC gamer/user I would not be worried so much. Again, it's the big volume sizes that save QLC here.

Performance

The devil is in the details, look closely at trace results and we can conclude that the SSD is comparable to your normal range PCIe 3.0 SSD like a Samsung 970 EVO. However, when transferring large files, the Z44Q will perform admirably thanks to the PCIe 4.0 interface. Cardea Zero Z44Q's sequential write performance appears to be excellent. During the writing process to the pseudo-SLC cache, the transfers hover at an excellent 3.5 GB/s and are sustained for an extremely long period of time. In actuality, the SSD will first fill its whole capacity with SLC data before beginning to write straight to QLC storage media. Write speeds are reduced by more than 90 percent in this stage, with maximum rates of roughly 250 MB/s only. It goes without saying that temporarily ceasing write activity will cause the SLC cache to immediately free up capacity. This means that full write rates will be accessible immediately after giving the drive time to settle down. 

Write holes

A problem facing QLC written memory, once your FIFO write buffers (pSLC) run dry, QLC will face what we refer to as the QLC/TLC write hole and drop in performance pretty bad. Team has got it covered as we do not run into any write holes. We ran our 64GB write test multiple times and perf did not cave in (under the condition that the SSD is properly cooled with a heatsink). A recent review of a colleague's website showed that the write hole only was visible after writing close to 500GB, so that's just a non-existent issue. If you do have larger than 500GB workloads then after that value the write perf drops significantly, however will restore back to normal once all has been written or if you pause writing for a few seconds. This QLC SSD actually has a big whopper of a pseudo-SLC write buffer, likely 512GB of it. Basically, this is what NAND provisioning is all about. All hot data is written to SLC first and then moved to QLC. We haven't noticed significant enough perf drops. So the reality is that you need to push extremely hard to reach that point of slow writes. Honestly, you'll be hard-pressed to run into it. Not even copying a 100 GB file multiple times made us stumble into it. 

PCIe Gen 4.0

It has to be stated, the SSD is plenty fast, but PCIe Gen 4.0 SSDs have been designed to be faster. The bottlenecks kick in at that 7 GB/sec marker. We're looking at an NVMe SSD that reads sustained in that 4~5 GB/sec zone and roughly 3.5 GB/sec for writes. These are still huge numbers of course, but could be faster.

Concluding

As a piece of hardware, the Z44Q is a product we can recommend, but as stated the people will judge on endurance mostly, QLC has a bit of that scare factor. Realistically writing 50 GB per day every day each year would still make this 4TB SSD last almost 44 years, and that is true fact. That's 22 years for the 2TB model. I see QLC SSDs as a good option for laptops and cold storage, say NAS storage of your movie or game collection. If you want a bit more ease of mind then your next stop is a TLC-based SSD. However, there is another major influencing dynamic to consider in the NAND arena, ... pricing. QLC will need to come down in price significantly for it to make enough sense. Currently, you can find TLC-based SSDs in more or less the same performance class going for less than 15 cents per GB. Of course end-users will fee towards the TLC NAND product series for reasons aforementioned. Performance-wise this QLC product did not disappoint at all but at PCIe Gen 4.0 you'd expect a little more. The dreaded QLC write hole has been polished away by a huge buffer, so for normal and everyday usage and say a gaming PC, really it's an advised product multiple times faster than any of the fastest SATA3 SSDs. But pricing levels for QLC, as stated, need to come down before a larger audience will accept and adopt QLC based SSDs. The huge plus today is volume size, a 4 TB version of this SSD is incredibly nice to have, and that is the sole advantage of QLC. If you want it, this is a proper product offering good overall performance and really good IOPS, and sustained performance. However for QLC to get accepted, prices need to come down, at least substantially below TLC NAND prices.

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