[DRBD-announce] drbd-9.1.13 and drbd-9.2.2

[Philipp Reisner]

Hi,

This is the final release of drbd-9.1.13 and drbd-9.2.2. In the number
of changed lines, the work on improving quorum is the most significant
change in this release. Here is a minor example that highlights the
improvement.

Consider nodes A, B, and C with ascending node IDs.

        C       | C is diskless
       / \      | A is Secondary and has a backing disk
      A---B     | B is Secondary, having a backing disk

Step 1: A does a graceful disconnect from B

        C       | C is diskless and has quorum
       / \      | A is Secondary with disk and has quorum
      A   B     | B is Secondary with disk and has quorum

Step 2: A disconnects unexpectedly from C (with --force or crash)

        C       | C is with quorum since it is part of 2 out of 3
         \      | A is **without** quorum
      A   B     | B is with quorum since it is part of 2 out of 3

Step 3: C disconnects unexpectedly from B (with --force or crash)

        C       | C is without quorum
                | A is without quorum
      A   B     | B is ...

With earlier versions of DRBD B had lost quorum as well. Starting
with drbd-9.1.13 (9.2.2) DRBD keeps quorum in this situation.
It can do that because it knows that A can not have quorum.


**Important news regarding drbd-9.2:**

We fixed all known regressions of drbd-9.2.0. drbd-9.2 has heavily
improved resync behavior when coordinating between application I/O and
resync I/O, and handling resyncs of thinly provisioned backing
storage. It has improved latency for all write requests.


I recommend all users of drbd-9.2.x upgrading to 9.2.2. In case you
decided to run drbd-9.1.x, upgrade within the 9.1 branch only necessary,
if you are likely to profit from something on the changelog.


9.1.13-rc.1 (api:genl2/proto:110-121/transport:17)
--------
 * when calculating if a partition has quorum, take into account if
   the missing nodes might have a quorum
 * fix forget-peer for diskless peers
 * clear the resync_again counter upon disconnect
 * also call the unfence handler when no resync happens
 * do not set bitmap bits when attaching to an up-to-date disk (late)
 * work on bringing the out-of-tree DRBD9 closer to DRBD in the upstream
   kernel; Use lru_cahche.ko from the installed kernel whenever possible

9.2.2-rc.1 (api:genl2/proto:110-121/transport:18)
--------
 * fix spurious PingAck timeout a second time; we need to use a drbd
   owned workqueue to guarantee the required low-latency replies
 * Fix connection abort during resync with log message
   "Unexpected resync write ack at ..." a regression of drbd-9.2
 * fix a race condition that can lead to NULL-ptr deref during resync
 * merged changes from drbd-9.1.13
  - when calculating if a partition has quorum, take into account if
    the missing nodes might have a quorum
  - fix forget-peer for diskless peers
  - clear the resync_again counter upon disconnect
  - also call the unfence handler when no resync happens
  - do not set bitmap bits when attaching to an up-to-date disk (late)
  - work on bringing the out-of-tree DRBD9 closer to DRBD in the upstream
    kernel; Use lru_cahche.ko from the installed kernel whenever possible

https://pkg.linbit.com//downloads/drbd/9/drbd-9.1.13.tar.gz
https://pkg.linbit.com//downloads/drbd/9/drbd-9.2.2.tar.gz

https://github.com/LINBIT/drbd/commit/834511a4957bba1a6aa4245a99ceebca5c42a4f2
https://github.com/LINBIT/drbd/commit/8435da3ec2a0a70dee0fedf354276d6f1c6ba708

-Phil