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linux:fs:btrfs_as_root [2016/04/21 08:07] niziak [Converting dirs into subvolumes] |
linux:fs:btrfs_as_root [2017/01/18 21:41] (current) niziak |
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| - btrfs utils version 3.17 | - btrfs utils version 3.17 | ||
| - | |||
| - | ===== Conversion ===== | ||
| - | <code bash> | ||
| - | fsck -f /dev/sda1 | ||
| - | fsck -f /dev/sda6 | ||
| - | |||
| - | btrfs-convert /dev/sda1 | ||
| - | </code> | ||
| - | |||
| - | Disk usage before conversion: used 1.56GB, free 2.53GB | ||
| - | after conversion: used 1.65GB, free 2.43GB | ||
| - | |||
| - | <code bash>btrfs check /dev/sda1</code> | ||
| - | |||
| - | ===== Update system ===== | ||
| - | Mount new root filesystem: | ||
| - | |||
| - | <code bash> | ||
| - | mount /dev/sda1 /mnt | ||
| - | 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" | ||
| - | mount /dev/sda1 somewhere, go to etc/fstab and update to new UUID: | ||
| - | |||
| - | UUID=a74f5787-aee1-4981-b7e6-fbd3cb6ac919 / btrfs defaults 0 1 | ||
| - | |||
| - | <code bash> | ||
| - | update-grub | ||
| - | grub-install /dev/sda | ||
| - | |||
| - | exit | ||
| - | |||
| - | reboot | ||
| - | </code> | ||
| - | |||
| - | and remove Live CD with Gparted | ||
| - | |||
| - | ===== rollback to ext FS ===== | ||
| - | Rollback to ext2 is possible. There is subvolume ext2_saved on filesystem. | ||
| - | <code bash>btrfs subvolume list /</code> | ||
| - | To delete backup | ||
| - | <code bash>btrfs subvolume delete /ext2_saved</code> | ||
| ===== Update to kernel 4 ===== | ===== Update to kernel 4 ===== | ||
| Line 79: | Line 35: | ||
| ===== Converting dirs into subvolumes ===== | ===== Converting dirs into subvolumes ===== | ||
| - | To make backups, snapshoting, 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. | + | 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. |
| To distinguish volumes from directories we will use @ character at beginning of subvolume name. This is Ubuntu naming convention for subvolumes. | To distinguish volumes from directories we will use @ character at beginning of subvolume name. This is Ubuntu naming convention for subvolumes. | ||
| Line 87: | Line 43: | ||
| * /@home | * /@home | ||
| * /@var | * /@var | ||
| + | |||
| + | Mount BTRFS filesystem (BTRFS root) to /mnt/btrfs. | ||
| ==== root ==== | ==== root ==== | ||
| - | * take a snapshot of root volume | + | * take a snapshot of root volume. Name of snapshot is '@' |
| - | * ''btrfs subvolume snapshot . @root'' | + | * ''btrfs subvolume snapshot /mnt/btrfs @'' |
| - | * make @root subvolume a default root | + | * delete files on BTRFS root (/mnt/btrfs) |
| - | * update <file | /etc/fstab> | + | * make @ subvolume a default root |
| - | UUID=739e6086-d925-4bdb-94f5-26d8c10dc171 / btrfs defaults,subvol=@root | + | * update fstab:<file | /etc/fstab>UUID=739e6086-d925-4bdb-94f5-26d8c10dc171 / btrfs defaults,subvol=@</file> |
| - | </file> | + | * OR |
| - | or | + | * get @ subvolume id ''btrfs subvolume list /mnt/btrfs'' |
| - | * set @root subvolume default mount path ''btrfs subvolume set-default @root /'' | + | * set default subvolume to use when system is mounted ''btrfs subvolume set-default 256 /mnt/btrfs'' |
| - | * | + | |
| - | * move directory to subvolume (cp --reflink is much faster on BTRFS) | + | |
| ==== subdirectories ==== | ==== subdirectories ==== | ||
| Line 105: | Line 62: | ||
| * move files into the new subvolume as if it were a directory | * move files into the new subvolume as if it were a directory | ||
| * ''mv /mnt/btrs/@/home/* /mnt/btrfs/@home/'' | * ''mv /mnt/btrs/@/home/* /mnt/btrfs/@home/'' | ||
| + | * ''cp --reflink'' is much faster on BTRFS | ||
| * remove old directory | * remove old directory | ||
| * ''rmdir /mnt/btrfs/@/home'' | * ''rmdir /mnt/btrfs/@/home'' | ||
| * update /etc/fstab to mount @home as /home | * update /etc/fstab to mount @home as /home | ||
| + | ===== fstab ==== | ||
| + | Do not use ''errors=remount-ro'' option which is not valid for BTRFS. | ||
| + | Example working fstab file: | ||
| + | <file | /etc/fstab> | ||
| + | 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 | ||