On 29/06/17 11:16, Gandalf Corvotempesta wrote: > 2017-06-29 12:14 GMT+02:00 Mateusz Korniak <mateusz-lists@xxxxxxxxxxxxxx>: >> One can read of all disks/partitions used by RAIDs by script >> /usr/share/mdadm/checkarray >> >> In many distros it is set to be performed monthly out-of-box. > > I know this and I'm running weekly. (just to be sure) > What Is unclear to me is why an hardware raid controller like LSI, has > two different kind of checks: patrol read and consistency check. Because they're two completely different things. A patrol check reads the entire disk. It doesn't give two hoots what the data is, it just cares that the data can actually be retrieved from the disk. A consistency check, on the other hand, wants to make sure that the data is correct. It will read both copies of a mirror and compare them. Or it will read the data from 4/5/6, calculate the parities, then read them from disk and compare them. In other words, a patrol check looks for a failing disk. A consistency check looks for corrupt data. (A consistency check does a patrol check as a side effect, but you might not want to do just that, as it is computationally much more expensive. You might want to do a patrol check every day, and a consistency check of a weekend.) Cheers, Wol -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
