On Sunday May 6, gmccullagh@xxxxxxxxx wrote: > On Sun, 06 May 2007, martin f krafft wrote: > > > Maybe the ideal way would be to have mdadm --monitor send an email on > > mismatch_count>0 or a cronjob that regularly sends reminders, until the > > admin logs in and runs e.g. /usr/share/mdadm/repairarray. You could certainly do that. If you configure mdadm to run a program for each 'monitor' event, you can detect the mismatch count from argv[3] when argv[1] == RebuildFinished. Though I suspect many people would be happy with running the 'repair' every month rather than just a 'check'. Maybe that should be a config option. > > > > Also, if a mismatch is found on a RAID1, how does md decide which copy is > > mismatched and which is correct? What about RAID 5/6/10? > > I think it just picks one at random. After all, how could you reliably > know which is right in a raid1 array? With raid5, I understand it just > updates the parity. I prefer to say "arbitrary" rather than "random". I think the current implementation uses the first readable device as the 'correct' one. Otherwise, this is correct. > > I had an idea to write an interactive userspace program which ran through > each block on each disk device to figure out which ones didn't match up and > then figure out whether it's within allocated filesystem space and if so, > which file or filesystem data was affected. This would hopefully enable a > user to figure out which block is wrong and correct things. > That would be awfully difficult as doing a reverse mapping (block -> file) is no-trivial in almost any filesystem, and you would want to (ultimately) do it for every filesystem... Might be educational though :-) NeilBrown - 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
