Hi Dean Thanks a lot for sharing this. I am not quite understand about these 2 commands. Why we want to add a pre-failing disk back to md4? mdadm --zero-superblock /dev/sde1 mdadm /dev/md4 -a /dev/sde1 Ming On Sun, 2006-04-23 at 18:40 -0700, dean gaudet wrote: > i had a disk in a raid5 which i wanted to clone onto the hot spare... > without going offline and without long periods without redundancy. a few > folks have discussed using bitmaps and temporary (superblockless) raid1 > mappings to do this... i'm not sure anyone has tried / reported success > though. this is my success report. > > setup info: > > - kernel version 2.6.16.9 (as packaged by debian) > - mdadm version 2.4.1 > - /dev/md4 is the raid5 > - /dev/sde1 is the disk in md4 i want to clone from > - /dev/sdh1 is the hot spare from md4, and is the clone target > - /dev/md5 is an unused md device name > > here are the exact commands i issued: > > mdadm -Gb internal --bitmap-chunk=1024 /dev/md4 > mdadm /dev/md4 -r /dev/sdh1 > mdadm /dev/md4 -f /dev/sde1 -r /dev/sde1 > mdadm --build /dev/md5 -ayes --level=1 --raid-devices=2 /dev/sde1 missing > mdadm /dev/md4 --re-add /dev/md5 > mdadm /dev/md5 -a /dev/sdh1 > > ... wait a few hours for md5 resync... > > mdadm /dev/md4 -f /dev/md5 -r /dev/md5 > mdadm --stop /dev/md5 > mdadm /dev/md4 --re-add /dev/sdh1 > mdadm --zero-superblock /dev/sde1 > mdadm /dev/md4 -a /dev/sde1 > > this sort of thing shouldn't be hard to script :) > > the only times i was without full redundancy was briefly between the "-r" > and "--re-add" commands... and with bitmap support the raid5 resync for > each of those --re-adds was essentially zero. > > thanks Neil (and others)! > > -dean > > p.s. it's absolutely necessary to use "--build" for the temporary raid1 > ... if you use --create mdadm will rightfully tell you it's already a raid > component and if you --force it then you'll trash the raid5 superblock and > it won't fit into the raid5 any more... > - > 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 - 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
