The DRBD Proxy processes can either be located directly on the machines where DRBD is set up, or they can be placed on distinct dedicated servers. A DRBD Proxy instance can server as proxy for multiple DRBD devices of multiple nodes.

DRBD Proxy is completely transparent to DRBD. Typically you will expect a high number of data packets in flight, therefore the activity log should be reasonably large. A big transfer log causes longer re-sync runs after the crash of a primary node. Therefore it is recommended to enable DRBD's csums-alg setting.

DRBD Proxy is configured in DRBD's main configuration file. It is configured by an additional options section called proxy and additional proxy on sections within the host sections.

Below is a DRBD configuration example for proxies running directly on the DRBD nodes:

resource r0 {
        protocol c;
        device     minor 0;
        disk       /dev/sdb1;
        flexible-meta-disk  /dev/sdb2;

	proxy {
	      compression on;
	      memlimit 100M;
	}

        on alice {
                address 127.0.0.1:7789;
                proxy on alice {
                        inside 127.0.0.1:7788;
                        outside 192.168.23.1:7788;
                }
        }

        on bob {
                address 127.0.0.1:7789;
                proxy on bob {
                        inside 127.0.0.1:7788;
                        outside 192.168.23.2:7788;
                }
        }
}

The inside IP address is used for communication between DRBD and the DRBD Proxy, whereas the outside IP address is used for communication between the proxies.

drbdadm offers the proxy-up and proxy-down subcommands to configure or delete the connection to the local DRBD Proxy process of the named DRBD resource(s). These commands are used by the start and stop actions which /etc/init.d/drbdproxy implements.

The DRBD Proxy has a low level configuration tool, called drbd-proxy-ctl. When called without any option it operates in interactive mode. The available commands are displayed by the 'help' command.

Help for drbd-proxy.
--------------------

add connection <name> <ip-listen1>:<port> <ip-connect1>:<port>
   <ip-listen2>:<port> <ip-connect2>:<port>
   Creates a communication path between two DRBD instances.

set memlimit <name> <memlimit-in-bytes>
   Sets memlimit for connection <name>

del connection <name>
   Deletes communication path named name.

show
   Shows currently configured communication paths.

show memusage
   Shows memory usage of each connection.

list [h]subconnections
   Shows currently established individual connections
   together with some stats. With h outputs bytes in human
   readable format.

list [h]connections
   Shows currently configured connections and their states
   With h outputs bytes in human readable format.

list details
   Shows currently established individual connections with
   counters for each DRBD packet type.

quit
   Exits the client program (closes control connection).

shutdown
   Shuts down the drbd-proxy program. Attention: this
   unconditionally terminates any DRBD connections running.