QRadar: How to check Distributed Replication Block Device status on an HA setup

Summary

Distributed Replicated Block Device (DRBD) is an open source distribution for replicated storage on the Linux platform. DRBD layers logical block devices over existing logical block devices on participating cluster nodes. Writes to the primary node are transferred to the lower-level block device and simultaneously propagated to the secondary node.

When HA is enabled, the /store file system on the QRadar appliance peers (primary and secondary) is replicated using the drbd feature. Every write request to /store, is replicated and written to the secondary peer node in real time, and then the write request "completes" and control is passed back to the Linux kernel. This is called a "synchronous mode" replication. This disk replication is run over the management interface (normally eth0) unless the system is configured with a crossover connection using another LAN interface. When a node is detected to be out of sync, data is automatically synchronized from the other node.