Creating an HA RDQM

You use the crtmqm command to create a high availability replicated data queue manager (RDQM).

About this task

You can create a high availability replicated data queue manager (RDQM) as a user in the mqm group if the mqm user can use sudo. If the user can also SSH to each node without a password, then you only need run the create RDQM command on one node to create the RDQM on all three nodes. Otherwise you must be root to create an RDQM, and you must run commands on all three nodes.

Procedure

To create an RDQM as a user in the mqm group:
1. Ensure that the mqm user can use sudo to run commands and can connect to each server using SSH without a password.
2. Enter the following command:
```
crtmqm -sx [-fs FilesystemSize] qmname
```
  where qmname is the name of the replicated data queue manager. You can optionally specify the file system size for the queue manager (that is, the size of the logical volume which is created in the drbdpool volume group).
  The command attempts to use SSH to connect to the other nodes in the cluster as the mqm user. If connection is successful, the secondary instances of the queue manager are created on the nodes. Otherwise, you must create the secondary instances and then run the crtmqm -sx command (as described for user root).
To create an RDQM as user root:
1. Enter the following command on each of the nodes that are to host secondary instances of the RDQM:
```
crtmqm -sxs [-fs FilesystemSize] qmname
```
  where qmname is the name of the replicated data queue manager. You can optionally specify the file system size for the queue manager (that is, the size of the logical volume which is created in the drbdpool volume group). You must specify the same file system size for the RDQM on all three nodes in the HA group.
  The command creates a secondary instance of the RDQM.
2. On the remaining node, enter the following command:
```
crtmqm -sx [-fs FilesystemSize] qmname
```
  where qmname is the name of the replicated data queue manager. You can optionally specify the file system size for the queue manager.
  The command determines if the secondary instance of the queue manager exist on the other two nodes. If secondaries exist, the command creates and starts the primary queue manager. If the secondaries do not exist, you are instructed to run the crtmqm -sxs command on each of the nodes.
Apart from the DataPath (-md) and LogPath (-ld) arguments, all arguments that are valid for creating a standard Linux® queue manager are also valid for a primary replicated data queue manager.

Note: When you create an RDQM, the next free port number above 7000 is allocated for the replication link. If it is discovered that the chosen port is used by another application, the crtmqm command fails with the AMQ6543 error and that port is added to an exclude list. You must delete the secondary instances of the queue manager, then run the crtmqm command again.