Replacing coordination points for server-based fencing in an online cluster


Replacing coordination points for server-based fencing in an online cluster
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Use the following procedure to perform a planned replacement of customized coordination points (CP servers or SCSI-3 disks) without incurring application downtime on an online VCS cluster.

Note:

If multiple clusters share the same CP server, you must perform this replacement procedure in each cluster.

You can use the vxfenswap utility to replace coordination points when fencing is running in customized mode in an online cluster, with vxfen_mechanism=cps. The utility also supports migration from server-based fencing (vxfen_mode=customized) to disk-based fencing (vxfen_mode=scsi3) and vice versa in an online cluster.

However, if the VCS cluster has fencing disabled (vxfen_mode=disabled), then you must take the cluster offline to configure disk-based or server-based fencing.

See Deployment and migration scenarios for CP server.

You can cancel the coordination point replacement operation at any time using the vxfenswap -a cancel command.

See About the vxfenswap utility.

To replace coordination points for an online cluster

Ensure that the VCS cluster nodes and users have been added to the new CP server(s). Run the following commands:
```
# cpsadm -s cpserver -a list_nodes
# cpsadm -s cpserver -a list_users
```
If the VCS cluster nodes are not present here, prepare the new CP server(s) for use by the VCS cluster.

See the Cluster Server Installation Guide for instructions.

Ensure that fencing is running on the cluster using the old set of coordination points and in customized mode.

For example, enter the following command:

# vxfenadm -d

The command returns:

I/O Fencing Cluster Information:
================================
Fencing Protocol Version: <version>
Fencing Mode: Customized
Cluster Members:
* 0 (sys1)
1 (sys2)
RFSM State Information:
node 0 in state 8 (running)
node 1 in state 8 (running)

Create a new /etc/vxfenmode.test file on each VCS cluster node with the fencing configuration changes such as the CP server information.
Review and if necessary, update the vxfenmode parameters for security, the coordination points, and if applicable to your configuration, vxfendg.

Refer to the text information within the vxfenmode file for additional information about these parameters and their new possible values.
From one of the nodes of the cluster, run the vxfenswap utility.
The vxfenswap utility requires secure ssh connection to all the cluster nodes. Use - n to use rsh instead of default ssh. Use - p <protocol>, where <protocol> can be ssh, rsh, or hacli.
```
#  vxfenswap [-n | -p <protocol>]
```
Review the message that the utility displays and confirm whether you want to commit the change.
- If you do not want to commit the new fencing configuration changes, press Enter or answer n at the prompt.
```
Do you wish to commit this change? [y/n] (default: n) n
```
  The vxfenswap utility rolls back the migration operation.
- If you want to commit the new fencing configuration changes, answer y at the prompt.
```
Do you wish to commit this change? [y/n] (default: n) y
```
  If the utility successfully completes the operation, the utility moves the/etc/vxfenmode.test file to the /etc/vxfenmode file.
Confirm the successful execution of the vxfenswap utility by checking the coordination points currently used by the vxfen driver.
For example, run the following command:
```
# vxfenconfig -l
```

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