Only "partially" because the journal is not locked during the merge, so
there's a small window where a different git-annex process could write info
to the journal that overwrites info taken from the merge.
That could be dealt with by locking, but the lock would really need to be
around the whole git-annex, to only let one run at a time. Otherwise, even
with the journal locked during the merge, another git-annex could already
be running, generate an overwriting change, and only store it in the journal
after the merge was complete. And similarly, two git-annex processes could
fight and overwrite each other's information independant of any merging.
So, a toplevel lock for git-annex may get added; it's something I've
considered before, as these potential, unlikely problems are not new.
(OTOH, fsck will deal with such problems.)
git-annex allows managing files with git, without checking the file
contents into git. While that may seem paradoxical, it is useful when
dealing with files larger than git can currently easily handle, whether due
to limitations in memory, checksumming time, or disk space.
For documentation, see doc/ or <http://git-annex.branchable.com/>
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