PostgreSQL 12 High Availability Cookbook - Third Edition

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Some might claim that any data invalidation is excessive. DRBD has its own safeguards to protect against inadvertent data copies. While true, server pools are not always cleaned up properly. Invalidating the data on pg2 does more than protect pg1 from being adversely affected if or when pg2 reconnects. We've effectively ensured pg2 cannot contribute data to any other DRBD cluster as a primary node.

However, we can go even further. We can actually physically destroy all traces of DRBD data on the decommissioned node. These commands on pg2 will do the work for us:

drbdadm down pg
drbdadm wipe-md pg
dd if=/dev/zero of=/dev/VG_DRBD/LV_DATA bs=1024 count=1024

The first drbdadm command stops the DRBD device itself. The second command ...