DRBD stands for Distributed Replicated Block Device. DRBD is meant to operate below the filesystem layer, mirroring the contents of one server's storage to another at the block level. This means the operating system doesn't even know that its data is located on another server as well. Having trouble imagining how it works? We hope the following diagram will help:
As we can see here, DRBD acts as an abstraction from the disk device that normally hosts our PostgreSQL database. The primary benefit we gain from this situation is that data is always located on at least two servers at all times. If one server crashes and its storage is ...
