4.2.7. Troubleshooting

Check DRBD sync status

To check the current DRBD synchronization status, type the following command:

# cat /proc/drbd

Sample output master node

version: 8.3.16 (api:88/proto:86-97)
GIT-hash: a798fa7e274428a357657fb52f0ecf40192c1985 build by phil@Build64R6, 2013-09-27 16:00:43

 1: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
    ns:265832 nr:0 dw:263360 dr:108049 al:54 bm:14 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

Sample output slave node

version: 8.3.16 (api:88/proto:86-97)
GIT-hash: a798fa7e274428a357657fb52f0ecf40192c1985 build by phil@Build64R6, 2013-09-27 16:00:43

 1: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r-----
    ns:0 nr:265832 dw:265832 dr:0 al:0 bm:12 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

These examples show a correctly working sync. Both nodes show „cs:Connected“. This indicates all nodes are connected and replicating. Also, it is running as primary node „ro:Primary/Secondary“ and the sync is up to date („ds:UpToDate / UpToDate“). The second node is running as secondary and is also connected.

Should any node show „cs:StandAlone“, then the synchronization has stopped. This could have been caused by a split-brain occurrence or any communication error. To resolve this, you need to choose which node is the current one and force a re-sync from the other node. You can type the following commands on the secondary node (make sure) to achieve this:

# drbdadm detach sb4 
# drbdadm attach sb4 
# drbdadm invalidate sb4 
# drbdadm syncer sb4            [* this command might not be available ]
# drbdadm connect sb4

After entering the commands, you can follow the sync process with „cat /proc/drbd“. The process should take around 7 minutes, depending on the amount of data.

Log file

The Corosync log can be found in:

/var/log/corosync.log

This log file contains info about the HA stack.