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MySQL Utilities 1.5 Manual
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8.7.5 Key administrative tasks

The cluster management tool can then be used to migrate the resources between machines:

[root@host1 ~]#  crm resource migrate g_mysql host2

Specifying the g_mysql group migrates all resources in the group and implicitly any colocated resources as well. If for any reason a resource cannot be properly started up or shut down, it becomes unmanaged. In this case, we have to manually put it back to a managed state. For example, this could mean that we would have to fix an issue that blocked the shutdown, kill or stop some processes, and run the following command:

[root@host1 ~]# crm resource cleanup 'resource'

The components of this stack are designed to cope with component failures but there may be cases where a sequence of multiple failures could result in DRBD not being confident that the data on the two hosts is consistent. In the event that this happens DRBD breaks the connection. Should this happen, we need to identify which of the two hosts has the correct data and then have DRBD resynchronize the data; for the steps below, it is assumed that host1 has the correct data:

[root@host2]# drbdadm secondary clusterdb_res
[root@host2]# drbdadm -- --discard-my-data connect clusterdb_res

[root@host1]# drbdadm primary clusterdb_res
[root@host1]# drbdadm connect clusterdb_res

Before executing these steps, it is advised to check the error log(s) and run the following command to identify the DRBD's status:

shell> /etc/init.d/drbd status

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