I have set up regular scrub on my ZFS pools and am beginning to look at setting up smart check every now and then, but I have a distinct memory of an entry I am unable to find that one should not schedule overlapping times. Is there any such considerations one should take into account when it comes to scheduling, for example scrubs, resilvering and smart checks? scrubs and resilvering seem obvious, but between other disk maintenance operations? While I read some talking of not overlapping scrubs on multiple pools, should one consider it when running a smart check on an raid array and a scrub on an pool in the same system?
SnapOverflow
Short version: try to not overlap them, but not bother too much if it not possible. Limit surface scan test to avoid added wear on the HDDs.
Long version: SMART offline and short self checks lasts some minutes only, with a minimal performance impact. SMART long (also named extended self) checks reads the entire disk surface, lasting many hours. This latter kind of test can has some limited performance impact. Considering that many drives also have an internal surface scan test, and that ZFS scrubs actual data, I would avoid to frequently schedule a SMART long test to limit HDDs busy/duty time (and wear).