As of btrfs-progs-v4.12, the "btrfs subvolume show" command does not
print the full (absolute, resolved) path anymore [1]. Instead, it prints
the relative path to btrfs root (or "/" if it is the root).
The impact for btrbk is that we cannot fill our realpath_cache in
btrfs_subvolume_show() anymore. This is not fatal, but has the
following consequences:
- The "check for duplicate snapshot locations" may now miss
subvolumes specified by symlinks.
- If multiple "volume" sections point to the same subvolume (e.g. if
specified using symlinks) an additional "btrfs subvolume list" is
called. Note that the subvolume will still be recognized as
identical, and the btr_tree will not be rebuilt.
[1] btrfs-progs commit: b7df24aa5cddc4802b9938f56372b73869775cd9
Under "Example: laptop with usb-disk for backups" the readme stated that " snapshot_preserve 14d" will "keep daily snapshots for 14 days [..]". I believe that this is misleading, as it seems to imply that only one snapshot --the latest -- will be kept in that period, when in fact _all_ snapshots will be kept in that period.
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.
Axel Burri