This gets important when using an old backup disk as source.
In terms of btrfs send/receive, all subvolumes matching "uuid /
received_uuid" are valid backups.
Merged (amend) from pull request: #116
Verified by Axel Burri <axel@tty0.ch>
We set "--no-random-seed-file" because one of the btrbk
design principles is to not create any files unasked. Enabling
"--no-random-seed-file" creates ~/.gnupg/random_seed, and as
such depends on $HOME to be set correctly (think on running in
cron). From gpg2(1) man page:
--no-random-seed-file GnuPG uses a file to store its
internal random pool over invocations This makes random
generation faster; however sometimes write operations are not
desired. This option can be used to achieve that with the cost
of slower random generation.
Always overwrite destination .gz files during make install.
Otherwise you need to manually answer y to several prompts.
```gzip: /usr/share/doc/btrbk/README.md.gz already exists; do you wish to overwrite (y or n)? y```
We use "dd" instead of shell redirections, as it is common to have
special filesystems (like NFS, SMB, FUSE) mounted on the raw target
path. By using "dd" we make sure to write in reasonably large blocks
(default=128K), which is not always the case when using redirections
(e.g. "gpg > outfile" writes in 8K blocks).
Another approach would be to always pipe through "cat", which uses
st_blksize from fstat(2) (with a minimum of 128K) to determine the
block size.
- add sophisticated stream compression in run_cmd
- add special "compress" cmd_pipe item
- add special "redirect" cmd_pipe item:
use shell redirection instead of troublesome "dd of=".
- disable ssh_compression if stream_compression is set
bugfix for: 796b6bd9bf
Replace realpath with readlink in allowed commands. Commit 796b6bd substituted readlink for realpath in file "btrbk"; this commit propagates the change to ssh_filter_btrbk.sh.
When used without --inplace, rsync creates a new copy of the file and
moves it into place when it is complete, having the effect that btrfs
creates a new extent for the WHOLE file. With --inplace however, rsync
writes the updated data directly to the destination file, having the
effect that btrfs creates a new extent only for the differing part of
the file.
We already perform compression before gpg, such that compressing in gpg
is just a waste of time. Interestingly, it seems gpg is not trying to
recompress gzip[ed] input streams, as for the default gzip compression
this patch does not change performance. However, it is necessary for
the upcoming lz4 compression to show its real benefit.
Axel Burri