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Linux » Books » Administrative »
Linux FailSafe Administrator's Guide
(document number: 007-4322-002 / published: 2001-02-28)
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While a Linux FailSafe
system is running, you can move a resource group online to a particular node,
or you can take a resource group offline. In addition, you can move a resource
group from one node in a cluster to another node in a cluster. The following
subsections describe these tasks. Before you bring a resource group online for the first time, you should
run the diagnostic tests on that resource group. Diagnostics check system
configurations and perform some validations that are not performed when you
bring a resource group online. To bring a resource group online, you specify the name of the resource
and the name of the cluster which contains the node. You cannot bring a resource group online if the resource group has no
members. To bring a resource group fully online, HA services must be active.
When HA services are active, an attempt is made to allocate the resource group
in the cluster. However, you can also execute a command to bring the resource
group online when HA services are not active. When HA services are not active,
the resource group is marked to be brought online when HA services become
active. | Caution | Before bringing a resource group online in the cluster, you must be
sure that the resource group is not running on a disabled node (where HA services
are not running). Bringing a resource group online while it is running on
a disabled node could cause data corruption. For information on detached resource
groups, see Section 7.5.2. |
To bring a resource group online using the Cluster Manager GUI, perform
the following steps: On the left side of the display, click on the “Failover
Policies & Resource Groups” category. On the right side of the display click on the “Bring
a Resource Group Online” task link to launch the task. Enter the selected inputs. Click on “OK” at the bottom of the screen to complete
the task.
To bring a resource group online, use the following CLI command: cmgr> admin online resource_group A [in cluster B] |
If you have specified a default cluster, you do not need to specify
a cluster when you use this command. When you take a resource group offline, FaillSafe takes each resource
in the resource group offline in a predefined order. If any single resource
gives an error during this process, the process stops, leaving all remaining
resources allocated. You can take a Linux FailSafe resource group offline in any of three
ways: Take the resource group offline. This physically stops the
processes for that resource group and does not reset any error conditions.
If this operation fails, the resource group will be left online in an error
state. Force the resource group offline. This physically stops the
processes for that resource group but resets any error conditions. This operation
cannot fail. Detach the resource groups. This causes Linux FailSafe to
stop monitoring the resource group, but does not physically stop the processes
on that group. Linux FailSafe will report the status as offline and will not
have any control over the group. This operation should rarely fail.
If you do not need to stop the resource group and do not want Linux
FailSafe to monitor the resource group while you make changes but you would
still like to have administrative control over the resource group (for instance,
to move that resource group to another node), you can put the resource group
in maintenance mode using the “Suspend Monitoring a Resource Group”
task on the GUI or the admin maintenance_on command of
the CLI, as described in Section 7.5.4. | Caution | Detaching a resource group leaves the resources in the resource group
running at the cluster node where it was online. After stopping HA services
on that cluster node, you should not bring the resource group online onto
another node in the cluster, as this may cause data corruption. |
To take a resource group offline using the Cluster Manager GUI, perform
the following steps: Launch the Cluster Manager. On the left side of the display, click on the “Failover
Policies & Resource Groups” category. On the right side of the display click on the “Take
a Resource Group Offline” task link to launch the task. Enter the selected inputs. Click on “OK” at the bottom of the screen to complete
the task.
To take a resource group offline, use the following CLI command: cmgr> admin offline resource_group A [in cluster B] |
If you have specified a default cluster, you do not need to specify
a cluster in this command and the CLI will use the default. To take a resource group offline with the force option in effect, use
the following CLI command: cmgr> admin offline_force resource_group A [in cluster B] |
To detach a resource group, use the following CLI command: cmgr> admin offline_detach resource_group A [in cluster B] |
While Linux FailSafe is active, you can move
a resource group to another node in the same cluster. When you move a resource
group, you specify the following: The name of the resource group. The logical name of the destination node (optional). When
you do not provide a logical destination name, Linux FailSafe chooses the
destination based on the failover policy. The name of the cluster that contains the nodes.
To move a resource group using the Cluster Manager GUI, perform the
following steps: On the left side of the display, click on the “Failover
Policies & Resource Groups” category. On the right side of the display click on the “Move
a Resource Group” task link to launch the task. Enter the selected inputs. Click on “OK” at the bottom of the screen to complete
the task.
To move a resource group to another node, use the following CLI command: cmgr> admin move resource_group A [in cluster B] [to node C] |
You
can temporarily stop Linux FailSafe from monitoring a specific resource group,
which puts the resource group in maintenance mode. The resource group remains
on its same node in the cluster but is no longer monitored by Linux FailSafe
for resource failures. You can put a resource group into maintenance mode if you do not want
Linux FailSafe to monitor the group for a period of time. You may want to
do this for upgrade or testing purposes, or if there is any reason that Linux
FailSafe should not act on that resource group. When a resource group is in
maintenance mode, it is not being monitored and it is not highly available.
If the resource group's owner node fails, Linux FailSafe will move the resource
group to another node and resume monitoring. When you put a resource group into maintenance mode, resources in the
resource group are in ONLINE-MAINTENANCE state. The ONLINE-MAINTENANCE state for the resource is seen only on the node
that has the resource online. All other nodes will show the resource as ONLINE.
The resource group, however, should appear as being in ONLINE-MAINTENANCE state in all nodes. To put a resource group into maintenance mode using the Cluster Manager
GUI, perform the following steps: On the left side of the display, click on the “Failover
Policies & Resource Groups” category. On the right side of the display click on the “Suspend
Monitoring a Resource Group” task link to launch the task. Enter the selected inputs.
To resume monitoring a resource group using the Cluster Manager GUI,
perform the following steps: On the left side of the display, click on the “Failover
Policies & Resource Groups” category. On the right side of the display click on the “Resume
Monitoring a Resource Group” task link to launch the task. Enter the selected inputs.
To put a resource group into maintenance mode, use the following CLI
command: cmgr> admin maintenance_on resource_group A [in cluster B] |
If you have specified a default cluster, you do not need to specify
a cluster when you use this command. To move a resource group back online
from maintenance mode, use the following CLI command: cmgr> admin maintenance_off resource_group A [in cluster B] |
Linux FailSafe Administrator's Guide
(document number: 007-4322-002 / published: 2001-02-28)
table of contents | additional info | download
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