Review Adata SD810 External SSD review: 20Gbps speed on a budget, but not for pros

[Admin]

Adata's SD810 external SSD is priced low for a 20Gbps USB drive, and it performs well in many benchmarks. But fill up its SLC cache with fast writes and you'll have to live with hard drive-class speeds.

Adata SD810 External SSD review: 20Gbps speed on a budget, but not for pros : Read more

 

[cryoburner]

It's possible that the 2TB model has a larger cache, and so would write in the 1,800MBps range longer, but if the cache is dynamic, it's also going to drop once the drive gets close to full.

I imagine the cache is likely dynamic and gets smaller with a fuller drive, but why not test that with various levels of free space remaining on each of the drives tested? And how long does it take for the cache to recover back to full performance after the sustained writes have stopped? There seems to be a lot of relevant information missing, at least if the cache is going to be discussed in the review as a major talking point, with suggestions that it supposedly makes the drive unsuitable for "professional use".

Realistically, running out of cache after somewhere around 100GB of sustained 1.8GB/s writes over the course of a full minute on a 1TB drive will probably not be a particularly common scenario, even for most "professional" use cases. And even if it does happen on rare occasions, it shouldn't exactly be that big of a deal. Writing around 100GB within a minute is fast, but even when the cache is filled, writing another 100GBs of data within 6 or 7 minutes isn't exactly going to be a problem outside of some niche usage scenarios. Even if you were to initially copy a full 1TB of data to the drive to completely fill it, the process would only take about an hour, and that's not likely something that many are going to do on a daily basis.

And a drive that has less free space remaining might have less cache available, but how much less, and how does that compare to the other drives when at similar levels of free space? Some may maintain a larger minimum size for the cache, but none of that appears to be answered in the review, so it's kind of hard to draw a complete picture of how each of the drives compare in terms of sustained write performance under different conditions.