14.1.1.4. Setting Up a DRBD Secondary Node

The configuration process for setting up a secondary node is the same as for the primary node, except that you do not have to create the file system on the secondary node device, as this information is automatically transferred from the primary node.

To set up a secondary node:

  1. Copy the /etc/drbd.conf file from your primary node to your secondary node. It should already contain all the information and configuration that you need, since you had to specify the secondary node IP address and other information for the primary node configuration.

  2. Create the DRBD metadata on the underlying disk device:

    root-shell> drbdadm create-md all
  3. Start DRBD:

    root-shell> /etc/init.d/drbd start

Once DRBD has started, it starts to copy the data from the primary node to the secondary node. Even with an empty file system this takes some time, since DRBD is copying the block information from a block device, not simply copying the file system data.

You can monitor the progress of the copy between the primary and secondary nodes by viewing the output of /proc/drbd:

root-shell> cat /proc/drbd
version: 8.0.4 (api:86/proto:86)
SVN Revision: 2947 build by root@drbd-one, 2007-07-30 16:43:05
 0: cs:SyncSource st:Primary/Secondary ds:UpToDate/Inconsistent C r---
    ns:252284 nr:0 dw:0 dr:257280 al:0 bm:15 lo:0 pe:7 ua:157 ap:0
        [==>.................] sync'ed: 12.3% (1845088/2097152)K
        finish: 0:06:06 speed: 4,972 (4,580) K/sec
        resync: used:1/31 hits:15901 misses:16 starving:0 dirty:0 changed:16
        act_log: used:0/257 hits:0 misses:0 starving:0 dirty:0 changed:0

You can monitor the synchronization process by using the watch command to run the command at specific intervals:

root-shell> watch -n 10 'cat /proc/drbd'
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