I currently have a secondary pool (with raidz2) that I was originally going to use for my important documents, such as storage for Paperless-ngx, as raidz offers corruption detection and repair. The pool is encrypted.
However, I’m concerned about rebuild times (it’s a pool of 4 22TB drives). Is btrfs a better choice for this use case, or should I just go with raidz like I originally planned?
While redundancy in a drive setup helps, it’s not really a backup and thus not a “safe” way to store important information on it’s own.
That said, selecting the way you setup a raid system is based on risk and utility. I have a raid1 with a hotspare for important files. And use raid5 with 3&4 drives for less important stuff. You can also optimise for reading speed for example (as the same file can be drawn from multiple drives)
Like you said: RAID is not a backup. If it’s import follow at least the 3-2-1 rule. 3 copies on at least 2 different media, 1 of them off site.