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linux:fs:btrfs_as_root [2016/04/20 10:58] niziak |
linux:fs:btrfs_as_root [2017/01/18 21:41] (current) niziak |
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| - | ===== Conversion ===== | + | ===== Update to kernel 4 ===== |
| + | Edit /etc/apt/sources and add sid release | ||
| <code bash> | <code bash> | ||
| - | fsck -f /dev/sda1 | + | apt-get update |
| - | fsck -f /dev/sda6 | + | apt-get install linux-image-amd64 |
| - | + | apt-get install btrfs-tools | |
| - | btrfs-convert /dev/sda1 | + | update-initramfs -u |
| </code> | </code> | ||
| - | Disk usage before conversion: used 1.56GB, free 2.53GB | + | * ERROR: Warning: /sbin/fsck.btrfs doesn't exist, can't install to initramfs, ignoring. |
| - | after conversion: used 1.65GB, free 2.43GB | + | * EXPLANATION: "This is going to be changed back in the next version of btrfs-tools." |
| + | * SOLUTION: ln -s /bin/fsck.btrfs /sbin/fsck.btrfs | ||
| - | <code bash>btrfs check /dev/sda1</code> | + | Check btrfs-tools version |
| + | <code bash>/bin/btrfs version</code> | ||
| - | ===== Update system ===== | ||
| - | Mount new root filesystem: | ||
| - | <code bash> | + | ===== Converting dirs into subvolumes ===== |
| - | mount /dev/sda1 /mnt | + | To make backups, snapshots, moving much easier and faster, every directory you want to backup by snapshot should be a subvolume. Also root filesystem should be created in separate subvolume not in btrfs root. |
| - | for i in dev dev/pts proc sys ; do mount --bind /$i /mnt/$i ; done | + | |
| - | chroot /mnt | + | |
| - | </code> | + | |
| - | get new UUID of /dev/sda1 using "blkid" | + | To distinguish volumes from directories we will use @ character at beginning of subvolume name. This is Ubuntu naming convention for subvolumes. |
| - | mount /dev/sda1 somewhere, go to etc/fstab and update to new UUID: | + | |
| - | UUID=a74f5787-aee1-4981-b7e6-fbd3cb6ac919 / btrfs defaults 0 1 | + | Proposed subvolumes structure (where / is BTRFS root) |
| + | * /@ | ||
| + | * /@home | ||
| + | * /@var | ||
| - | <code bash> | + | Mount BTRFS filesystem (BTRFS root) to /mnt/btrfs. |
| - | update-grub | + | |
| - | grub-install /dev/sda | + | |
| - | exit | + | ==== root ==== |
| + | * take a snapshot of root volume. Name of snapshot is '@' | ||
| + | * ''btrfs subvolume snapshot /mnt/btrfs @'' | ||
| + | * delete files on BTRFS root (/mnt/btrfs) | ||
| + | * make @ subvolume a default root | ||
| + | * update fstab:<file | /etc/fstab>UUID=739e6086-d925-4bdb-94f5-26d8c10dc171 / btrfs defaults,subvol=@</file> | ||
| + | * OR | ||
| + | * get @ subvolume id ''btrfs subvolume list /mnt/btrfs'' | ||
| + | * set default subvolume to use when system is mounted ''btrfs subvolume set-default 256 /mnt/btrfs'' | ||
| - | reboot | ||
| - | </code> | ||
| - | and remove Live CD with Gparted | + | ==== subdirectories ==== |
| + | * On BTRFS root create a new subvolume | ||
| + | * ''btrfs subvolume create /mnt/btrfs/@home'' | ||
| + | * move files into the new subvolume as if it were a directory | ||
| + | * ''mv /mnt/btrs/@/home/* /mnt/btrfs/@home/'' | ||
| + | * ''cp --reflink'' is much faster on BTRFS | ||
| + | * remove old directory | ||
| + | * ''rmdir /mnt/btrfs/@/home'' | ||
| + | * update /etc/fstab to mount @home as /home | ||
| - | ==== rollback to ext FS ==== | + | ===== fstab ==== |
| - | Rollback to ext2 is possible. There is subvolume ext2_saved on filesystem. | + | Do not use ''errors=remount-ro'' option which is not valid for BTRFS. |
| - | <code bash>btrfs subvolume list /</code> | + | Example working fstab file: |
| - | To delete backup | + | <file | /etc/fstab> |
| - | <code bash>btrfs subvolume delete /ext2_saved</code> | + | UUID=ed730508-753e-4a7f-ac1e-bf8646f7bd63 / btrfs defaults,subvol=@,compress=no 0 0 |
| + | UUID=ed730508-753e-4a7f-ac1e-bf8646f7bd63 /var btrfs defaults,subvol=@var,compress=no 0 0 | ||
| + | UUID=ed730508-753e-4a7f-ac1e-bf8646f7bd63 /var/log btrfs defaults,subvol=@varlog,compress=no 0 0 | ||
| + | UUID=ed730508-753e-4a7f-ac1e-bf8646f7bd63 /home btrfs defaults,subvol=@home,compress=no 0 0 | ||
| + | UUID=ed730508-753e-4a7f-ac1e-bf8646f7bd63 /mnt/btrfs btrfs noauto,defaults,subvolid=5,compress=no 0 0 | ||
| + | </file> | ||
| + | To prevent systemd to halt system during startup if device is not found (nofail and x-systemd.device-timeout): | ||
| + | <file | /etc/fstab> | ||
| + | UUID=<the_device_uuid> /mount/point btrfs nofail,x-systemd.device-timeout=10,noatime,compress=lzo,autodefrag 0 0 | ||
| + | </file> | ||
| + | NOTE: do not use autodefrag - it consumes lots of cpu | ||