Rolling upgrade of OS in Oracle Cluster
Hi Friends, hope you are doing well.
Recently I did rolling upgrade
of OS from RHEL 6.4 to RHEL 7.4 in Oracle RAC 11gR2 (Two Nodes)
environment. I wanted to share the approach that I followed considering to minimize
the downtime as possible.
Please note that for OS
upgrade from RHEL 6.4 to 7.4, servers has to be reimaged.
Oracle supports the rolling
upgrade of the operating system in a cluster when both versions of the
operating system are certified with the version of Oracle Database you are
running.
Mixed operating system
versions are only supported for the duration of an upgrade (i.e. within 24
hours). The cluster should never be operated with mixed operating systems for
an extended period.
Followed the below steps for this OS upgrade. This is the
two node Oracle RAC (11gR2) environment.
1.
Upgrade OS to RHL7.4 in Node2:
a.
Relocate all DB services from Node2 to
Node1.
Example:
#
srvctl relocate service -d DB_Name -s Service_Name -i DB_Instance_2 -t DB_Instance_1
b. Remove
the Node2 from cluster. Before removing the node2, please take the backup from
node2 if anything needed.
c. Reimage
the server Node2 with RHEL 7.4 OS
d. Add
Node2 back to Oracle Cluster
2.
Upgrade OS to RHL7.4 in Node1:
a. Relocate all DB services from Node1 to Node2
Example:
#
srvctl relocate service -d DB_Name -s Service_Name -i DB_Instance_1 -t DB_Instance_2
b. Remove
Node1 from Cluster
c. Reimage
the server Node1 with RHEL 7.4 OS
d. Add
Node1 back to Oracle Cluster
References:
The below mentioned Oracle document provides detailed
steps for adding and deleting cluster nodes on Linux.
The below mentioned Oracle document provides more details
on having mixed operating systems versions during upgrade.