Nathan Kidd
2014-Feb-08 18:29 UTC
Recovering from persistent kernel oops on 'btrfs balance'
Hi, I added a 2nd device and 'btrfs balance' crashed (kernel oops) half way through, now I can only read the fs from a rawhide livedvd, but even that can't fix the fs (finish balance, or remove 2nd device to try again). I'd be grateful for any advice on getting back to a working btrfs filesystem. Details ====== Hardware： Asus P5G41T-M with Pentium dual core E2140，4GB ram, OS on ext4 drive, two 4TB Segate "NAS" SATA drives. On Ubuntu 13.04 x86_64 (3.8 kernel, btrfs-tools 0.19+20130117) 1. Install new 4TB drive (/dev/sdb), use gparted to create full-disk btrfs partition, mount on /ark copy ~500GB data, everything working well for a couple weeks 2. Install additional identical 4TB drive, Following https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices#Adding_new_devices 3. btrfs device add /dev/sdc /ark 4. btrfs balance start -dconvert=raid1 -mconvert=raid1 /ark 5. After ~1 hour, at about 50% (according to 'btrfs balance status', the system locks up with this displayed (sorry, JPEG): http://i.imgur.com/Ds9pnZV.jpg 6. System repeat same oops on startup 7. After removing /dev/sdc system boots but can't see anything on /ark I guess using a 3.8 kernel wasn't the smartest idea. Let's update. 8. Update to Ubuntu 13.11 x86_64 (3.11 kernel, btrfs-tools 0.19+20130705-1) 9. Now system boots with /dev/sdc plugged in but still can't see data on /ark, IIRC the balance command gave similar kernel oops. 10。 Fine I'll try Rawhide. From Jan 30, 2014, kernel 3.14.0-0.rc0.git17.1.fc21.x86_64 11. I can see data on /ark！ 12. If I try to 'btrfs balance resume' or 'btrfs balance cancel' I get roughly the same kernel oops: http://pastebin.ca/2634583 13. 'btrfs device delete /dev/sdc /ark' says it cannot be done while balance is underway 14. Help! Any suggestion on how to recover the btrfs fs? My last resort idea is pull /dev/sdb (which seems to have actual data that rawhide can see), format /dev/sdc ext4, plug both drives in again and copy from btrfs /dev/sdb to ext4 /dev/sdc, then wipe the btrfs fs on /dev/sdb and try again with the 3.11 kernel (or just with rawhide?). But that is a whole lot of copying it would be nice to avoid. Thanks, -Nathan -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html