[Drbd-dev] DRBD Bug Report : DRBD 9.0 after-resync-target not being called after resync / reconnect

[Farhan Khan]

Hello, I would like to report a bug:

Scenario:
- 2 nodes running as primary and secondary on CentOS 7.4 with pacemaker 
and corosync with dedicated link Gigabit link between nodes

Bug description and replication:
- Disconnect the link between nodes
      --> fence-peer is called and secondary node is correctly fenced
- Do not write any new data to primary while the link is broken
-Reconnect the link
      --> nodes reconnect and re-sync correctly
      --> after-resync-target is NOT called and location constraint remains

Further steps to manually trigger after-resync-target handler:
- wrote some data to primary
      --> correctly syncs with secondary
      --> after-resync-target is still not called

Temporary workaround:
- write a script to to write some data to primary node when it gets 
disconnected using something like  "dd if=/dev/zero of=speetest bs=64k 
count=1 conv=fdatasync"
      -->this triggers after-resync-target and location constraint is 
successfully removed

my config:
resource r0 {
     device               /dev/drbd0 minor 0;
     disk                 /dev/sda4;
     meta-disk            internal;
     on storage1 {
         node-id 0;
         address          ipv4 172.26.1.1:7790;
     }
     on storage2 {
         node-id 1;
         address          ipv4 172.26.1.2:7790;
     }
     net {
         protocol           C;
         sndbuf-size        0;
         max-buffers      8000;
         max-epoch-size   8000;
         after-sb-0pri    discard-least-changes;
         after-sb-1pri    discard-secondary;
         after-sb-2pri    call-pri-lost-after-sb;
         fencing          resource-only;
     }
     disk {
         md-flushes        no;
         al-extents       3833;
         resync-rate      90M;
         c-plan-ahead       2;
         c-fill-target     2M;
         c-max-rate       100M;
         c-min-rate       25M;
     }
     handlers {
         fence-peer       /usr/lib/drbd/crm-fence-peer.9.sh;
         after-resync-target /usr/lib/drbd/crm-unfence-peer.9.sh;
         pri-lost-after-sb /usr/lib/drbd/notify-pri-lost-after-sb.sh;
     }
}