Hi David, Thanks for the update, sorry for the delay, this email was sitting in my drafts folder. Instructions follow.
On 26 April 2016 at 05:23, David Alcorn <nrocl...@gmail.com> wrote: > > Nicholas: > > 1. My RAID array is partially filled and backed up. > 2. I prefer to mount by UUID. > 3. n/a > 4. the relevant content of my blkid is: > "/dev/sda1: UUID="AEF6-E013" TYPE="vfat" > PARTUUID="b4b9c894-aa4f-4c83-ba27-8919eaaeac49" > /dev/sda2: UUID="a428a1ea-5174-47b6-a894-521166a7a354" TYPE="ext2" > PARTUUID="e25bcabb-2fd3-4515-bf74-3a2f0c548fec" > /dev/sda3: UUID="1b413c7c-d39d-4c10-9f1d-4f3a21791c50" > UUID_SUB="e2d12168-c216-425f-9a82-6d46dad8ccc8" TYPE="btrfs" > PARTLABEL="primary" PARTUUID="1651d9f1-35ff-458b-ae64-bb6003c72159" > /dev/sdb: UUID="c2cf44d3-28e0-492a-9d51-00a41b71428d" > UUID_SUB="b4c6bbc5-ea80-4a79-89ca-333d351b09e5" TYPE="btrfs" > /dev/sdc: UUID="c2cf44d3-28e0-492a-9d51-00a41b71428d" > UUID_SUB="c4ac65e7-45bb-4450-9aa4-80a7fbebed3a" TYPE="btrfs" > /dev/sdd: UUID="c2cf44d3-28e0-492a-9d51-00a41b71428d" > UUID_SUB="5f55bf3b-8e82-4b50-8b62-5dc45c892281" TYPE="btrfs" > /dev/sde: UUID="c2cf44d3-28e0-492a-9d51-00a41b71428d" > UUID_SUB="5a12cbd5-bdc2-4258-9bc8-23d95cbb1db6" TYPE="btrfs" > > > I omitted /dev/sdf from my blkid content as it is an unused, > transitory drive that will be redeployed after "/" is moved to the > array. /dev/sda is my flash drive with separate partitions for efi > (vfat), /boot/ (ext2) and "/" (btrfs subvolume). Note: I'm guessing you read the Debian wiki entry on btrfs before 2016-03-14? If you read it after this date, I might need to make the fact that UEFI systems cannot boot from raw drives more explicit. Ok, here is how you move everything on your raid6 array to a subvolume--the goal is to have two subvolumes on your RAID6, one for rootfs, and one for whatever you're using the bulk storage for. I'm assuming you haven't yet created one, but I think these commands will still work, even if you have; you'll just have nested subvolumes in that case. Personally, I prefer alphanumeric subvolume naming, but I'll use the @ convention for clarity. These instructions assume that you've booted from you flash disk. Please note that I'm not sure if this will work if your flash rootfs is installed on subvolid=5... btrfs sub list / # If there is no output, make a note of it. mkdir /tmp/tank mount -o noatime UUID="c2cf44d3-28e0-492a-9d51-00a41b71428d" /tmp/tank btrfs sub list /tmp/tank cd /tmp/tank btrfs sub create @tank ls -1 | egrep -v '@tank' while read d; do mv "$d" @tank/; done # There! Now all your data is in a subvolume btrfs sub snap -r / /rootfs-snapshot btrfs send /rootfs-snapshot | btrfs receive /tmp/tank # if this fails for any reason, send the output to this mailing list, and mention if "btrfs sub list /" # had any output. # then umount /tmp/tank && sync btrfs property set /tmp/tank/rootfs-snapshot ro false && mv rootfs-snapshot @ # There! now everything except for /boot and /boot/efi is on your raid6 # You have a choice between following the following instructions or editing your grub command line. Personally I would choose to edit the grub command line. # if you choose do it this way, run these commands: # # sync # umount /tmp/tank # sync # reboot # # edit your grub command line by hitting the "e" key when the menu comes up. Find the bit that # says root= and make sure it looks something like # root=/dev/sdb ro rootflags=subvol=@ Boot it, and scroll down to the "IF YOU FOLLOWED" section. ##### alternatively ##### cd /tmp/tank/@ mount none -t proc proc mount -o bind /dev dev mount none -t sysfs sysfs mount -o bind /boot boot mount -o bind /boot/efi chroot ./ #### IF YOU FOLLOWED the "edit grub command line" method, start here #### editor /etc/fstab # change the first line, for / UUID=c2cf44d3-28e0-492a-9d51-00a41b71428d / btrfs subvol=/@,noatime 0 0 # if you have a line for your raid6 subvolume, find it, and change it to UUID=c2cf44d3-28e0-492a-9d51-00a41b71428d /some/location btrfs subvol=/@tank,noatime 0 0 # You just need to run the following command to get grub to use the rootfs on your raid6 cp -arx /boot /boot.bak update-grub grep '/@/' /boot/grub/grub.cfg # this should output something! If it doesn't, seek help on IRC. # What I would personally do is manually edit /boot/grub/grub.cfg... # At any rate if that grep command outputted nothing, your system won't boot. # restore booting from you /dev/sda with the following command # cp -arx /boot.bak/* /boot # /\ this /\ should allow your usb stick to continue booting. # Continuing could trash your grub installation on /dev/sda if grep '/@/' /boot/grub/grub.cfg # didn't provide any output. # If that grep verified that you'll be booting to @ as your rootfs, then it's safe to do the following: grub-install /dev/sda sync #### IF YOU FOLLOWED the "edit grub command line" method, you're done! ### ### alternatively (continued) #### exit umount proc dev sys boot/efi umount boot cd ../ && umount tank sync reboot And it should work ;-) Nicholas -- 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
