Showing DRBD inSync Status in Cluster Monitoring Tools Workaround

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Environment

SUSE Linux Enterprise High Availability Extension 12 all Service Packs
SUSE Linux Enterprise High Availability Extension 15 all Service Packs

Situation

When building a Highly Available NFS Storage with DRBD using SLE HAE "Pacemaker" the only way to check if DRBD is inSync is by running "drbdadm status". This is very important because only if the Synchronisation is in sync the Resource Agent "Cluster" will promote the Secondary in case of Failure of the Primary.

Also, this information is visible via "crm status -A" under node attrebitute for DRBD resource.

Resolution

The following trick will add a new dummy resource to the cluster that will show if secondary DRBD is inSync or not.

Assuming the DRBD resource name is: drbd_ERP
Create a file ( inSync-Flag-DRBD.crm.txt ) with:

primitive PrimaryData Dummy
clone inSync PrimaryData
location lo-inSync-Data inSync \
        rule -inf: master-drbd_ERP ne 10000

then run:

crm configure load update inSync-Flag-DRBD.crm.txt

In case DRBD is inSync it will be running:

# crm resource status inSync
resource inSync is running on: ha2
resource inSync is running on: ha3

# crm status
  * Clone Set: inSync [PrimaryData]:
    * Started: [ ha2 ha3 ]

In case the sync is broken the result would be:

# crm resource status inSync
resource inSync is running on: ha2
resource inSync is NOT running

# crm status
  * Clone Set: inSync [PrimaryData]:
    * Started: [ ha2 ]
    * Stopped: [ ha3 ]

This will help avoid triggering failover when second node not in sync.

Additional Information

Check the SOK flag for SAP HANA: Showing SOK Status in Cluster Monitoring Tools Workaround

Disclaimer

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