Hi, "md/raid10:md5: sdf: redirecting sector 2979126480 to another mirror" I've actually been seeing these messages very occasionally across many machines for years but have never found anything wrong so kept putting investigation of it to the bottom of my TODO list. I have even in the past upon seeing this done a full scrub and check and found no issue. Having just seen one of them again now, and having some spare time I tried to look into it. So, this messages comes from here: https://github.com/torvalds/linux/blob/v5.8/drivers/md/raid10.c#L1188 but under what circumstances does it actually happen? This time, as with the other times, I cannot see any indication of read error (i.e. no logs of that) and no problems apparent in SMART data. err_rdev there can only be set inside the block above that starts with: if (r10_bio->devs[slot].rdev) { /* * This is an error retry, but we cannot * safely dereference the rdev in the r10_bio, * we must use the one in conf. …but why is this an error retry? Nothing was logged so how do I find out what the error was? Cheers, Andy