DRBD® (Distributed Replicated Block Device) is an open source, software‑based, shared‑nothing block storage replication solution for Linux, designed primarily to deliver high-performance, high‑availability (HA) data services by mirroring local block devices between nodes in real time, either synchronously or asynchronously. Implemented deep in the Linux kernel as a virtual block‑device driver, DRBD ensures local read performance with efficient write‑through replication to peer(s). User‑space utilities like drbdadm, drbdsetup, and drbdmeta enable declarative configuration, metadata management, and administration across installations. Originally built for two‑node HA clusters, DRBD 9.x extends support to multi‑node replication and integration into software‑defined storage (SDS) systems such as LINSTOR, making it suitable for cloud‑native environments.