On 4 March 2010 12:25, Asdo <asdo@xxxxxxxxxxxxx> wrote: > Alex Boag-Munroe wrote: >> >> Hi guys... >> >> Yes I am an idiot. I was changing the chunk size of my RAID5 array >> last night from 64kb to 256kb and left it running overnight. During >> the night we had a power outage. >> >> This is where the idiot part comes in. The backup file is on a >> filesystem that's part of the RAID5 array, so obviously I am unable to >> start it. I completely forgot the filesystem I specified for >> --backup-file was part of the same array. >> >> Once you're all done pointing and laughing, can you let me know if I >> am totally screwed? I've a lot of data here that I -really- don't >> want to lose... >> >> Please help.. >> >> Idiot. >> > > Firstly I will say that I have never faced this situation, so please wait > for someone more knowledgeable to reply before trying. > > Supposing the resync cannot be continued after a power failure (which I am > not sure)... > > My idea is that the reshape progresses linearly so one of the two > filesystems (either the original one or backup) should be accessible. If the > power failed when the reshape was within the first filesystem, the second > filesystem should be somehow accessible, if it failed when the reshape was > within the second filesystem, the first filesystem should be somehow > accessible. > > In this situation I guess you need to go to the hard route: you will > probably need to recreate the array with all the drives specified exactly in > the same order, using all the original options (you can get info from every > drive with mdadm --examine /dev/sdXY), and the chunksize either set at 64k > or at 256k (you try both), and specifying --assume-clean so that it does not > start to resync, and then set it --readonly before doing anything else. Then > you will probably be able to do some experiments try mounting one of the two > filesystems. > > Thinking again, I guess there is a situation which will prevent you to see > both filesystems... this is the case if 64kb prevents you to see the good > filesystem and 256k prevents you to see the LVM metadata :-( You use LVM > right? In this case you might need to "find" your filesystem by mounting the > device with progressively increasing offsets from the beginning, without the > help of LVM. And this will work only if your good partition in LVM was > contiguous (LVM allows holes). > > Anyway, wait other replies. > > Good luck > > Asdo > > > Hi Asdo. Yes I am using LVM. I'm not entirely sure how to go about messing with the mounting as you describe, I've never had to do it. Is this with the mount command? I do keep getting an error from lvm, "incorrect metadata area header checksum", with both chunk=64 and chunk=256 during the recreate. Thank you for your reply. -- Alex Boag-Munroe Lack of planning on your part does not constitute an emergency on mine. -- 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
