Caution
This is an advanced topic. Use at your own risk and ALWAYS backup your data before.
Useful Commands
View DRBD Status
cat /proc/drbd
Reload all parameters
drbdadm adjust jtelshared
Disconnect the share (useful for planned maintenance)
drbdadm disconnect jtelshared
Down the share (useful for planned maintenance)
drbdadm down jtelshared
Up the share
drbdadm up jtelshared
Set the node to primary
drbdadm primary jtelshared
Connect the share
drbdadm connect jtelshared
Split Brain
Background
See also:
https://docs.linbit.com/doc/users-guide-84/s-resolve-split-brain/
Symptoms
cat /proc/drbd --> GIT-hash: a4d5de01fffd7e4cde48a080e2c686f9e8cebf4c build by mockbuild@, 2017-09-15 14:23:22 1: cs:StandAlone ro:Primary/Unknown ds:UpToDate/DUnknown r----- ns:0 nr:119823323 dw:119823323 dr:2128 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0
cs:StandAlone means the node is not connected.
This should be visible on both sides.
Find out which node is active in the PCS cluster
pcs status --> Cluster name: portal Stack: corosync Current DC: acd-store1 (version 1.1.16-12.el7_4.7-94ff4df) - partition with quorum Last updated: Sun Mar 18 18:05:32 2018 Last change: Fri Feb 16 00:07:51 2018 by root via cibadmin on acd-store2 2 nodes configured 3 resources configured Node acd-store1: standby Online: [ acd-store2 ] Full list of resources: Resource Group: haproxy_group ClusterDataJTELSharedMount (ocf::heartbeat:Filesystem): Started acd-store2 ClusterIP (ocf::heartbeat:IPaddr2): Started acd-store2 samba (systemd:smb): Started acd-store2 Daemon Status: corosync: active/enabled pacemaker: active/enabled pcsd: active/enabled
In the example above, the first node is in standby. The most important thing to check, is on which server the resources are started.
In this case, the resources are started on acd-store2.
This will therefore be defined as the NON BROKEN node.
Standby the broken node in the PCS cluster
This command can be run on either machine.
pcs cluster standby acd-lb-broken --> Verify this with pcs status
On broken node
Note: the first command will probably throw an error. Also, the share may not be mounted. This is OK.
umount /srv/jtel/shared drbdadm disconnect jtelshared drbdadm secondary jtelshared drbdadm connect --discard-my-data jtelshared
On the healthy node
drbdadm primary jtelshared drbdadm connect jtelshared
Check re-sync activity
The re-sync might take a long time.
Watch the status of this using:
cat /proc/drbd
Example output:
[root@storage01 ~]# cat /proc/drbd version: 8.4.10-1 (api:1/proto:86-101) GIT-hash: a4d5de01fffd7e4cde48a080e2c686f9e8cebf4c build by mockbuild@, 2017-09-15 14:23:22 1: cs:SyncTarget ro:Secondary/Primary ds:Inconsistent/UpToDate C r----- ns:0 nr:1411538 dw:121234862 dr:2128 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:184698664 [>....................] sync'ed: 0.8% (180368/181744)M finish: 26:12:15 speed: 1,940 (2,760) want: 2,120 K/sec
Tune the transfer (Second Node)
If the transfer is going to take ages, then tune it on the broken node:
drbdadm disk-options --c-plan-ahead=0 --resync-rate=110M jtelshared
Put broken node back to primary
drbdadm primary jtelshared --> Verify this with cat /proc/drbd
Restart PCS node
pcs cluster unstandby acd-lb-broken --> Verify this with pcs status
Untune the transfer (Second Node)
If the transfer was tuned, then untune it (on the broken node).
Note: it won't hurt to run this command anyway.
drbdadm adjust jtelshared
Check everything
pcs status cat /proc/drbd # On some other linux machines ls /home/jtel/shared # Windows dir //acd-store/shared