Contradicting statements about use of hardlinks in documentation

[puenka]

In the documentation (stable and master) under Usage/General/File Systems, it is stated that

Hardlinks are needed for borg upgrade --inplace

However, in the borg-upgrade documentation it says that

Unless --inplace is specified, the upgrade process first creates a backup copy of the repository, in REPOSITORY.before-upgrade-DATETIME, using hardlinks.

which contradicts the above. From my experience when trying to use a WebDAV mount, using borg upgrade without --inplace fails due to the lack of hard linking capability.

Except for the mentioned issue of the repository not being recoverable in case of an error during a new snapshot process, is it generally safe to perform a (secondary of course) borg backup on a file system that does not support hard links (e.g. a WebDAV mount) by always using the --inplace option? Does this even work with create? On my mount it fails.

[ThomasWaldmann]

Need to have a look at the code for this.

In general, you should only use borg upgrade if the docs / changelog tell you to do so.

[ThomasWaldmann]

Where exactly is the contradiction? Did you see the Unless?

[puenka]

First just from a linguistical level:
The first statement says that hardlinks are needed if the inplace option is specified.
The second statement says that hardlinks are needed except if (i.e. unless) the inplace option is specified (thus any operation mode needs hardlinks?).

Also interpreting the content, it makes sense to me that the explanation of how hardlinks are being used in the second statement refers to the case without inplace, because the creation of a backup copy is omitted when using the option.

[ThomasWaldmann]

Ah, right, so first needs to be rephrased to:

"Hardlinks are needed for borg upgrade (if --inplace is not given)."

[puenka]

Yes, that's what I thought (but I don't have the code insight to actually argue about it)!
However I do think that I once had an error with a non-hardlinking file system already at init or at create, but that needs further investigation because this might not have been the exact reason why it failed...but that's just anecdotal anyways and doesn't really bother me at the moment.