Next Gen NVMe SD Card Review: The SM2708 Controller Serves it Hot and Fast
by Ganesh T S on September 9, 2021 9:00 AM EST- Posted in
- Storage
- NAND
- flash
- NVMe
- Silicon Motion
- Memory Cards
- 3D TLC
- SD Express
Long-Term Performance Evaluation
A few of the benchmarks are repeated on the memory card after subjecting it to the extended usage simulation.
Sequential Access - fio Workload
Re-processing the fio workload in the used mode gives an idea of long-term performance consistency (whether there is appreciable degradation in performance as the amount of pre-existing data increases and / or the card is subject to wear and tear in terms of amount and type of NAND writes).
| fio Sequential Workload [Used] | |
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In the SD Express mode, the card's SLC cache has essentially run out by the time the workload starts for the used case. So, we do not see the ~375MBps level seen in the fresh pass. However, there is no drop to 30 MBps either, as the card is able to maintain a steady 75 MBps almost all through. In fact, the fio workload completed faster to fill up 90% of the card capacity in the used pass compared to the fresh pass. The reads are slightly slower in the used pass, but the relative variations are similar. In the UHS-I mode, the writes start slower in the used pass, but the consistency is better compared to the fresh pass - essentially similar to the SD Express case. Reads are consistent in both passes at around 70 MBps.
Performance Restoration - CrystalDiskMark
The traditional memory card use-case is to delete the files on it after the import process is completed. Some prefer to format the card either using the PC, or, through the options available in the camera menu. The first option is not a great one, given that flash-based storage devices run into bandwidth issues if garbage collection (processes such as TRIM) is not run regularly. Different memory cards have different ways to bring them to a fresh state. Silicon Motion specified that SD Express cards need to be formatted in NVMe mode in order to restore performance.
In order to test out the effectiveness of the performance restoration process, we run the default sequential workloads in CrystalDiskMark before and after the formatting. Note that this is at the end of all our benchmark runs, and the card is in a used state at the beginning of the process.
| CrystalDiskMark [Used] Benchmarks | |
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In the used pass, the reads drop from 890 MBps to 733 MBps, and writes from 418 MBps to 95 MBps for the sequential workloads in the SD Express case. Other access traces see similar drops. The UHS-I case also sees a similar drop in relative performance.
| CrystalDiskMark [Refreshed] Benchmarks | |
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Upon formatting in SD Express mode, the performance gets restored to around 878 MBps / 415 MBps). However, formatting in UHS-I mode has no effect, as the refreshed CrystalDiskMark numbers are very similar to the numbers seen in the used case.
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eastcoast_pete - Thursday, September 9, 2021 - link
Those temperatures and power draws are way too high for what is probably the main use scenario: removable storage in high-resolution handheld cameras. They're also too high for potential use as removable storage, again mainly for video, in future Smartphones, once Android counterparts to Apple's upcoming iPhone Pro Max become available. That can reportedly use ProRes as file format to save videos, and ProRes eats storage space for breakfast.bananaforscale - Thursday, September 9, 2021 - link
Temps are certainly too high, but power draw not necessarily. That peak draw of 4.58W is ~1.1A at 4.2V, so you could power one off a single 18650 cell for a couple of hours assuming peak is constant, which it won't be.Fulljack - Thursday, September 9, 2021 - link
I think it's more intended for state-of-the-art digital camera that output high bitrate, high resolution video. one of the limiting factor are storage speed. having this on what seems like a laptop on your shoulders would help portability a lot.at_clucks - Friday, September 10, 2021 - link
At that point many users simply invest in cameras that output to an external SSD, at least with something like a CFast to SSD adapter.schuckles - Friday, September 10, 2021 - link
Whether these cards are usable as is really depends on your workload. I would have liked to see something like the anadrech light benchmarked and include the MBPS/watt to know how realistic that 4 watt workload is. Also curious what the idle/standby power of the card itself is.PaulHoule - Thursday, September 9, 2021 - link
How much heat could you remove from that kind of thing if you made the exterior out of metal and pressed it between two cold plates with a strong spring? I'd like to give an SDExpress card the same treatment as the "CPU" on an IBM 3090.shelbystripes - Thursday, September 9, 2021 - link
So… CFExpress cards are stupid fast, but get hot just doing sustained read (copying a full 256GB card’s contents to a computer all at once). And this is putting the same thing in an even smaller form factor. Of course the end result is inevitable.For photography this is still valuable, the cards are fast enough even in UHS-I mode for sustained burst in most cameras, and then having PCIe speeds for clearing the contents quickly to a PC is quite handy. But for video… these things will get hot, and compact camera thermals are already a nightmare. The Canon EOS R5 can technically shoot 8K video, but do it for very long and the damn thing overheats. The more you add awful thermal properties inside a compact environment like that, the worse off you are…
spaceship9876 - Thursday, September 9, 2021 - link
you forgot to mention ufs cards.Einy0 - Thursday, September 9, 2021 - link
Wow, 96C that will leave a mark!Kamen Rider Blade - Thursday, September 9, 2021 - link
When are regular sized SD cards going to go up in size?1TB Micro SD Cards already exists.
I calculate that if you make optimal use of the physical space of a SD card, you can get 4.5 TiB of storage using existing 512 GiB Nand Flash cells.
Wouldn't you want an entire regular sized SD card with 4.5 TiB of storage?