Am 03.01.2014 23:28, schrieb Jim Salter: > I'm using Ubuntu 12.04.3 with an up-to-date 3.11 kernel, and the > btrfs-progs from Debian Sid (since the ones from Ubuntu are ancient). > > I discovered to my horror during testing today that neither raid1 nor > raid10 arrays are fault tolerant of losing an actual disk. > > mkfs.btrfs -d raid10 -m raid10 /dev/vdc /dev/vdd /dev/vdd /dev/vde > mkdir /test > mount /dev/vdb /test > echo "test" > /test/test > btrfs filesystem sync /test > shutdown -hP now > > After shutting down the VM, I can remove ANY of the drives from the > btrfs raid10 array, and be unable to mount the array. In this case, I > removed the drive that was at /dev/vde, then restarted the VM. > > btrfs fi show > Label: none uuid: 94af1f5d-6ad2-4582-ab4a-5410c410c455 > Total devices 4 FS bytes used 156.00KB > devid 3 size 1.00GB used 212.75MB path /dev/vdd > devid 3 size 1.00GB used 212.75MB path /dev/vdc > devid 3 size 1.00GB used 232.75MB path /dev/vdb > *** Some devices missing > > OK, we have three of four raid10 devices present. Should be fine. Let's > mount it: > > mount -t btrfs /dev/vdb /test > mount: wrong fs type, bad option, bad superblock on /dev/vdb, > missing codepage or helper program, or other error > In some cases useful info is found in syslog - try > dmesg | tail or so > > What's the kernel log got to say about it? > > dmesg | tail -n 4 > [ 536.694363] device fsid 94af1f5d-6ad2-4582-ab4a-5410c410c455 devid 1 > transid 7 /dev/vdb > [ 536.700515] btrfs: disk space caching is enabled > [ 536.703491] btrfs: failed to read the system array on vdd > [ 536.708337] btrfs: open_ctree failed > > Same behavior persists whether I create a raid1 or raid10 array, and > whether I create it as that raid level using mkfs.btrfs or convert it > afterwards using btrfs balance start -dconvert=raidn -mconvert=raidn. > Also persists even if I both scrub AND sync the array before shutting > the machine down and removing one of the disks. > > What's up with this? This is a MASSIVE bug, and I haven't seen anybody > else talking about it... has nobody tried actually failing out a disk > yet, or what?
Hey Jim, keep calm and read the wiki ;) https://btrfs.wiki.kernel.org/ You need to mount with -o degraded to tell btrfs a disk is missing. Joshua -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
