RMR and BRMR

RMR (Reliable Multicast over RTRS) is a kernel module that provides active-active block-level replication over RDMA. It guarantees delivery of IO to a group of storage nodes and handles resynchronization of data directly between storage nodes without involving the compute client.

BRMR (Block device over RMR) sits on top of RMR and exposes a standard Linux block device (/dev/brmrX) backed by an RMR pool. Together, RMR and BRMR provide a single-hop replication and resynchronization solution for RDMA-connected storage clusters.

Project Status: In-development

RMR is under active development and is not ready for production use. Expect:

• Bugs, crashes, and data-loss scenarios that have not yet been fixed
• API, sysfs interface, and on-disk format changes without migration
• Code paths marked TODO / FIXME that are pending refactor or correction

Not suitable for: production workloads, or storing data you care about.

Building from source

RMR and BRMR are out-of-tree Linux kernel modules.

• Supported kernel version: v6.12. The linux-6.12.y stable branch is recommended.

• Install kernel headers matching the target kernel (linux-headers-$(uname -r) on Debian/Ubuntu).

• The following RTRS config options must be enabled in the kernel:

  CONFIG_INFINIBAND_RTRS=m
  CONFIG_INFINIBAND_RTRS_CLIENT=m
  CONFIG_INFINIBAND_RTRS_SERVER=m
  

• Run make in the source-code repository root.

• Load modules in dependency order: rtrs-*, then rmr-*, then brmr-*. Unload in reverse order.

See the User/admin guide to RMR cluster management for a full two-node bring-up.

License

RMR and BRMR are licensed under GPL-2.0-or-later. See COPYING for the full license text.