Billy Crook wrote: > It would be even nicer if there were a way to hot-transfer one > raid component to another without setting anything faulty. I suppose > you could make all the components of the real array be single disk > raid1 arrays for that purpose. Then you could have one extra disk set > aside for this sort of scrubbing, and never even be down one of your > parities. I guess I should add that onto my todo list.... IMHO This one should be high on the todo list. Especially if it's a pre-requisite for other improvements to resilience. Right now, if a drive fails or shows signs of going bad then you get into a very risky situation. I'm sure most here know that the risk is because removing the failing drive and installing a good one to re-sync puts you in a very vulnerable position; if another drive fails (even one bad block) then you lose data. The solution involves raid1 - but it needs a twist of raid5/6. http://arctic.org/~dean/proactive-raid5-disk-replacement.txt I think this is what was discussed: Assume md0 has drives A B C D D is failing E is new * add E as spare * set E to mirror 'failing' drive D (with bitmap?) * subsequent writes go to both D+E * recover 99+% of data from D to E by simple mirroring * any md0 or D->E read failures on D are recovered from reading ABC not E unless E is in sync. D is not failed out. (and it's these tricks that stops users from doing all this manually) * any md0 sector read failure on ABC can still (hopefully) be read from D even if not yet mirrored to E (also not possible * once E is mirrored, D is removed and the job is done Personally I think this feature is more important than the reshaping requests; of course that's just one opinion :) David -- 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
