You can stop cluster services without stopping services
and applications.
To stop cluster services without stopping your applications:
- Enter the fastpath smit cl_admin or smitty hacmp.
- Select System Management (C-SPOC) and press Enter.
- Select Manage HACMP Services > Stop Cluster Services and press Enter.
- Choose Unmanage resource groups.
No matter what type of resource group you have, if you
stop cluster services on the node on which this group is active and
do not stop the application that belongs to the resource group,
HACMP puts the group into an UNMANAGED state and keeps the application
running according to your request.
The resource group that contains
the application remains in the UNMANAGED state (until you tell HACMP
to start managing it again) and the application continues to run.
While in this condition, HACMP and the RSCT services continue to run,
providing services to ECM VGs that the application servers may be
using.
You can tell HACMP to start managing it again either
by restarting Cluster Services on the node, or by using SMIT to move
the resource group to a node that is actively managing its resource
groups. See Starting HACMP cluster services with manually managed
resource groups for more information.
If you have instances
of replicated resource groups using the Extended Distance capabilities
of the HACMP/XD product, the UNMANAGED SECONDARY state is used for
resource groups that were previously in the ONLINE SECONDARY state.
You
can view the new states of the resource groups using the cluster utilities clstat and clRGinfo .
You
cannot dynamically reconfigure (DARE) the cluster configuration while
some cluster nodes have resource groups in the unmanaged state.
Warning about placing resource groups in an unmanaged
state
When you stop cluster services on a node and place
resource groups in an UNMANAGED state, HACMP stops managing the resources
on that node. HACMP will not react to the individual resource failures,
application failures, or even if the node crashes.
Because the
resources of a system are not highly available when you place resource
groups in an unmanaged state, HACMP prints a message periodically
that the node has suspended managing the resources.
The ability
to stop a node and place resource groups in an UNMANAGED state is
intended for use during brief intervals for applying updates or for
maintenance of the cluster hardware or software.
When you may
want to stop HACMP cluster services without stopping applications
When
you may want to stop HACMP cluster services without stopping applications
In
general, HACMP cluster services are rarely the cause of problems in
your configuration. However, you may still want to stop HACMP cluster
services on one or more nodes, for example, while troubleshooting
a problem or performing maintenance work on a node.
Also, you
may want to stop HACMP cluster services from running without disrupting
your application if you expect that your activities will interrupt
or stop applications or services. During this period of time, you
do not want HACMP to react to any planned application "failures" and
cause a resource group to move to another node. Therefore, you may
want to remove HACMP temporarily from the picture.
