Re:Demystifying OpenZFS 2.0
by walrus01 on Thursday November 18, 2021 @12:32PM
(#29268075)
another consideration is that the "cheap" 4TB SSDs are things like quad-level cells, such as the samsung 870 QVO, which are slightly better in a $ per GB ratio, but also suffer in ultimate GB written lifespan for cell endurance wear-out. Thus the reason why the samsung "pro" are almost double the cost.
if you needed to write a LOT (let's say something like a sustained 70MB per second all the time) but the data rate was not particularly high, you might easily wear out a RAIDZ2 composed of 2TB-4TB sized cheap SSDs and kill them in a fairly short period of time, when the same RAIDZ2 composed of 2.5" 15mm height 5TB spinning drives, or 3.5" 14-16TB drives would successfully run for many years.
also re: cheap SSDs, the quad level cell tech and write cache is a big limitation in sustained write speeds:
if you needed to write a LOT (let's say something like a sustained 70MB per second all the time) but the data rate was not particularly high, you might easily wear out a RAIDZ2 composed of 2TB-4TB sized cheap SSDs and kill them in a fairly short period of time, when the same RAIDZ2 composed of 2.5" 15mm height 5TB spinning drives, or 3.5" 14-16TB drives would successfully run for many years.
also re: cheap SSDs, the quad level cell tech and write cache is a big limitation in sustained write speeds:
https://www.firstpost.com/tech/news-analysis/samsung-870-qvo...