How to freeze host in vcs

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how to freeze host in vcs

In this article we are going to discuss about how to freeze host in vcs. We need to understand why we have to freeze vcs cluster host. If you are performing any task like os patching or vcs related upgrade and your task need server reboot if you are not freezing cluster then automatic failover of service group takes place. So freezing service group becomes critical to avoid failover of service groups to another active node in cluster.

If service group frozen cluster will keep monitoring resources in cluster but it will now allow to make resources or service group for onlining or offlining which prevents automatic failover of resources or service group. Freezing might be of two category. It may be temporary or persistent. Impact of temporary freeze will not be retained across reboots. For VCS configurations to remain in same status persistent freeze is required.

We have considered here that you must be having already configured VCS related path in your .profile for commands to work without absolute path ie /etc/VRTS,/var/VRTSvcs & /opt/VRTSvcs has been included in your profile.

Temporarily  Freezing Service Group

When we freeze service group temporarily and if you restart VCS completely service group 
will automatically unfreezed on restart.To freeze and unfreeze service group you can do 
using below command line utilities.
# hagrp -freeze <SG>                                
# hagrp -unfreeze <SG>
Where <SG> stands for service group name.

Persistently  Freezing Host

As mentioned above this will freeze vcs host in event of reboot related need to avoid automatic failover of resources and resource group to another host in cluster.

Freezing the Cluster Host Persistently
# hagrp -offline SG -sys system                        # Making SG offline.
# haconf -makerw                                           # Making configuration writable
# hagrp -freeze SG –persistent                        # Freezing Persistently
# haconf -dump -makero                                # Making configuration read-only.

Once you are done with your activity and reboot you need to unfreeze service group with persistent option only.

Unfreezing the Cluster Host Persistently

# haconf -makerw                                              # Making configuration writable 
# hagrp -unfreeze SGSAPCI –persistent              # Unfreezing Persistently 
# hagrp -online SG -sys system                          # Making SG online. 
# haconf -dump -makero                                  # Making configuration read-only.

That,s it about how to freeze host in vcs to avoid automatic failover of service group to another host while performing any task on host which required reboot of host .

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RSY Digital World

RSY Digital World Founder & [email protected] Digital World. A UNIX Linux expert having a more than 20 years of experience in Solaris Red Hat Linux HP-UX AIX Unixware Open Server Veritas Storage Cloud Bigdata and many more in UNIX LINUX Infrastructure technologies.


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