Merge pull request #2445 from ThomasWaldmann/update-docs3

Update docs

src/borg/archiver.py

@@ -2842,7 +2842,20 @@ class Archiver:
                                help='repository to prune')
 
         upgrade_epilog = process_epilog("""
-        Upgrade an existing Borg repository.
+        Upgrade an existing, local Borg repository.
+
+        When you do not need borg upgrade
+        +++++++++++++++++++++++++++++++++
+
+        Not every change requires that you run ``borg upgrade``.
+
+        You do **not** need to run it when:
+
+        - moving your repository to a different place
+        - upgrading to another point release (like 1.0.x to 1.0.y),
+          except when noted otherwise in the changelog
+        - upgrading from 1.0.x to 1.1.x,
+          except when noted otherwise in the changelog
 
         Borg 1.x.y upgrades
         +++++++++++++++++++
@@ -2874,8 +2887,13 @@ class Archiver:
 
         Currently, only LOCAL repositories can be upgraded (issue #465).
 
-        It will change the magic strings in the repository's segments
-        to match the new Borg magic strings. The keyfiles found in
+        Please note that ``borg create`` (since 1.0.0) uses bigger chunks by
+        default than old borg or attic did, so the new chunks won't deduplicate
+        with the old chunks in the upgraded repository.
+        See ``--chunker-params`` option of ``borg create`` and ``borg recreate``.
+
+        ``borg upgrade`` will change the magic strings in the repository's
+        segments to match the new Borg magic strings. The keyfiles found in
         $ATTIC_KEYS_DIR or ~/.attic/keys/ will also be converted and
         copied to $BORG_KEYS_DIR or ~/.config/borg/keys.