On 8/4/2020 8:52 AM, Celejar wrote:
On Tue, 4 Aug 2020 10:26:32 +0100 Jonathan Dowland <jon+debian-user@dow.land> wrote:On Tue, Aug 04, 2020 at 01:32:24AM -0700, David Christensen wrote:jdupes looks interesting, and should work on any file system that supports hard links. I expect BorgBackup either calls jdupes or implements similar functionality: https://linuxcommandlibrary.com/man/jdupes.htmlI'm fairly sure Borg stores files by a hash of their contents and maintains a separate index of names→hashes for each generation.Indeed: "To actually perform the repository-wide deduplication, a hash of each chunk is checked against the chunks cache, which is a hash-table of all chunks that already exist." https://borgbackup.readthedocs.io/en/stable/internals.html
I prefer DAR for several reasons. First of all, as I mentioned before, DAR is the only backup solution of which I am aware that can restore not only deleted or corrupted files, but which can also restore deletions. This means DAR can restore any or all files one chooses in a batch, but then if requested can go back and delete files which were deleted at a later time but prior to additional DAR backups.
As a simple example, if one backs up an entire system, deletes several files, then does another backup, DAR can restore the system to the exact state of the last backup without losing any files in the archive, yet not restoring the deleted files. This eliminates the need to ever "refresh" the main backup, keeping every file that was ever on the system, yet eliminating the need to delete files from a restore performed at a later time.
DAR is also designed to work with removable media. In this respect, it is similar to the venerable TAR utility, but while TAR is not designed to work with random access media, DAR is. In fact, the name DAR is an acronym for Disk ARchive.
Packages are avail;able for Windows, MacOS, FreeBSD, and nearly all Linux distros, including Debian.
http://dar.linux.free.fr/doc/Features.html http://dar.linux.free.fr/