Sik wrote:
I also found tests where they got anywhere from 200-500 GB of read/write activity a day for (the equivalent of) 10 years before the SSD started complaining. I doubt that I've ever owned a HDD that would perform that well...
The tests probably used sequential I/O, unless they were testing enterprise SSDs. Such as perform appending writes and remove the written files in whole before repeating the process. This reduces the wear significantly. (This is also the wrong way to test the worst case sustained write performance.)
Whether or not random writes are a common workload is another story. But the reason this matters is because when you perform random writes, the effective volume of data written to flash is multiplied by (total space) / (TRIM reclaimed space + manufacturer reserved space). This amplification cannot be avoided by FTL. Sequential I/O is garbage collected without write amplification, assuming moderately intelligent FTL. That is why TBW should be rated at maximum allocation, based on original write volume, not post-amplification. Indeed, the low-end TBW at the moment is equivalent to 20GB per day for commodity models.
@OP
So, basically, looking at the numbers, I have to agree that HDDs have lower durability. The specs show that they have DWPD (diskfull writes per day) or TB/year ratings at about or lower to those of SSDs. Commodity HDDs occasionally have a slight lead. Looking at the specs so far, SSDs are the top tier of the endurance market. Also, HDDs suffer from modes of failure not present in SSDs. With technologies like 3d-NAND or non-NAND, the SSD lead will obviously further.
Still, for life span, I would make sure I have enough RAM, which is a good idea anyway and optionally keeping some free space.
Here is an
article comparing endurance of several enterprise HDDs and SSDs. And these
SSD tests are performed with sequential I/O, which surpasses the rated TBW significantly.