Hi -
dduper is an offline dedupe tool. Instead of reading whole file blocks and
computing checksum, It works by fetching checksum from BTRFS csum tree. This
hugely improves the performance.
dduper works like:
- Read csum for given two files.
- Find matching location.
- Pass the location to ioctl_ficlonerange directly
instead of ioctl_fideduperange
By default, dduper adds safty check to above steps by creating a
backup reflink file and compares the md5sum after dedupe.
If the backup file matches new deduped file, then backup file is
removed. You can skip this check by passing --skip option. Here is
sample cli usage [1] and quick demo [2]
Some performance numbers: (with -skip option)
Dedupe two 1GB files with same content - 1.2 seconds
Dedupe two 5GB files with same content - 8.2 seconds
Dedupe two 10GB files with same content - 13.8 seconds
dduper requires `btrfs inspect-internal dump-csum` command, you can use
this branch [3] or apply patch by yourself [4]
[1]
https://gitlab.collabora.com/laks/btrfs-progs/blob/dump_csum/Documentation/dduper_usage.md
[2] http://giis.co.in/btrfs_dedupe.gif
[3] git clone https://gitlab.collabora.com/laks/btrfs-progs.git -b dump_csum
[4] https://patchwork.kernel.org/patch/10540229/
Please remember its version-0.1, so test it out, if you plan to use dduper real
data.
Let me know, if you have suggestions or feedback or bugs :)
Cheers.
Lakshmipathi.G
