Release 0.5.11

Another bunch of fixes, including important ones. Now OSDs are stable in SSD+HDD
configurations and everything is mostly ready for the merge of master branch.

Features:

- Add min_flusher_count configuration (good for HDDs)
- Shuffle PGs for better data device utilisation
- Make OSDs benefit from the immediate_commit=small setting if it's applicable

Bug fixes:

- Rework client code to fix write ordering during operation replay
- Rework error handling code so OSDs don't crash in reaction to a crash of their peer OSDs
- Fix several block layer problems related to the journal, some of which
  were leading to double allocations of the same block during journal replay
- Fix monitors crashing during the removal of OSD keys from etcd
- Fix data fsyncs being incorrectly disabled when only disable_journal_fsync was set
- Always zero out unused part of request/reply headers
- Fix some theoretically possible read/write ordering issues
- Don't try to "recover" misplaced objects if it would make them degraded
- Fix heartbeats sometimes preventing OSD to establish connections

debian/changelog

@@ -1,4 +1,4 @@
-vitastor (0.5.10-1) unstable; urgency=medium
+vitastor (0.5.11-1) unstable; urgency=medium
 
   * Bugfixes