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linux:fs:btrfs [2021/03/02 09:43] niziak |
linux:fs:btrfs [2021/05/02 11:34] (current) niziak |
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| !!! It is possible to remove any device if there is free space to which data can be moved during removal. | !!! It is possible to remove any device if there is free space to which data can be moved during removal. | ||
| - | |||
| - | ==== btrfs property ==== | ||
| - | <code bash> | ||
| - | btrfs property set <file> compression <zlib|lzo|zstd> | ||
| - | </code> | ||
| - | ===== Deduplication ===== | ||
| - | External tool to find duplicated extens available | ||
| - | [[https://github.com/markfasheh/duperemove]] | ||
| - | |||
| - | Simply do 'make' and 'make install' | ||
| - | Following binaries will be installed: | ||
| - | * btrfs-extent-same | ||
| - | * csum-test | ||
| - | * duperemove | ||
| - | * hashstats | ||
| - | * show-shared-extents | ||
| - | |||
| - | Recursively find duplicates in <dir> | ||
| - | <code>duperemove -r <dir></code> | ||
| - | |||
| - | The same as above, but make real deduplication (on BTRFS only) | ||
| - | <code>duperemove -rd <dir></code> | ||
| - | |||
| - | Increase deduplication chance by reducing block size to 4k: | ||
| - | <code>duperemove -b 4k -rd <dir></code> | ||
| - | |||
| - | This deduplication works nice, it can find some shared parts inside Maildir. | ||
| - | |||
| - | |||
| - | ===== Subvolumes ===== | ||
| - | |||
| - | <code> | ||
| - | btrfs subvolume create /BTRFS/sub1 | ||
| - | btrfs subvolume create /BTRFS/sub2 | ||
| - | btrfs subvolume create /BTRFS/sub3 | ||
| - | </code> | ||
| - | |||
| - | <code> | ||
| - | btrfs subvolume list /BTRFS | ||
| - | ID 256 gen 234 top level 5 path sub1 | ||
| - | ID 257 gen 227 top level 5 path sub2 | ||
| - | ID 258 gen 228 top level 5 path sub3 | ||
| - | </code> | ||
| - | |||
| - | Mount subvolume | ||
| - | <code>mount -o subvol=sv1/sv12 /dev/sdb /mnt</code> | ||
| - | |||
| - | Getting data size on each subcvolume: | ||
| - | * Enable quota on btrfs ''btrfs quota enable /'' | ||
| - | * Install script [[https://github.com/agronick/btrfs-size]] | ||
| - | |||
| - | |||
| - | ==== Different mount options ==== | ||
| - | NOT SUPPORTED YET: | ||
| - | In general, btrfs doesn't _yet_ have the runtime infrastructure to handle | ||
| - | per-subvolume mount options. The on-device format and general approach | ||
| - | in the kernel was designed to allow it, and it's on the roadmap, it just | ||
| - | hasn't been done... yet. | ||
| - | |||
| - | To make workaround it is possible to use attributes on files or directories: | ||
| - | * C disable COW feature (for newly created directories or zero sized files). New files in directores with C attributes will be created with C attrib. But not subdirectories. | ||
| - | * c enable compression | ||
| - | |||
| - | ==== Move data between subvolumes ==== | ||
| - | See `cp` command arg: | ||
| - | When --reflink[=always] is specified, perform a lightweight copy, where the data blocks are copied only when modified. If this is not possible the copy fails, or if | ||
| - | --reflink=auto is specified, fall back to a standard copy. | ||
| - | |||
| - | <code bash> | ||
| - | cp -pr --reflink=always srcDirectory dstDirectory/ | ||
| - | rm -r srcDirectory | ||
| - | </code> | ||
| ====== Scrub ====== | ====== Scrub ====== | ||
| Line 142: | Line 70: | ||
| ====== Issues ====== | ====== Issues ====== | ||
| + | |||
| ===== Compression type 0x3 not supported ===== | ===== Compression type 0x3 not supported ===== | ||
| GRUB 2.02 doesn't support ZSTD compression. | GRUB 2.02 doesn't support ZSTD compression. | ||
| - | Solution is to exlude `/boot` from ZSTD compression (below) or install more recent Grub (from Debian Bullseye) | + | Solution is to exlude ''/boot'' from ZSTD compression (below) or install more recent Grub (from Debian Bullseye) |
| <code bash> | <code bash> | ||
| sudo btrfs filesystem defragment -v -r -czlib /boot | sudo btrfs filesystem defragment -v -r -czlib /boot | ||
| sudo btrfs property set /boot compression zlib | sudo btrfs property set /boot compression zlib | ||
| + | # disable compression for newly created files | ||
| + | chattr -Rc /boot | ||
| </code> | </code> | ||