Using Serviceguard Extension for RAC, 6th Edition, April 2008

A Software Upgrades
Serviceguard Extension for RAC (SGeRAC) software upgrades can be done in the two
following ways:
• rolling upgrade
• non-rolling upgrade
Instead of an upgrade, moving to a new version can be done with:
• migration with cold install
Rolling upgrade is a feature of SGeRAC that allows you to perform a software upgrade
on a given node without bringing down the entire cluster. SGeRAC supports rolling
upgrades on version A.11.15 and later, and requires all nodes to be running on the
same operating system revision and architecture.
Non-rolling upgrade allows you to perform a software upgrade from any previous
revision to any higher revision or between operating system versions but requires
halting the entire cluster.
The rolling and non-rolling upgrade processes can also be used any time one system
needs to be taken offline for hardware maintenance or patch installations. Until the
upgrade process is complete on all nodes, you cannot change the cluster configuration
files, and you will not be able to use any of the new features of the
Serviceguard/SGeRAC release.
There may be circumstances when, instead of doing an upgrade, you prefer to do a
migration with cold install. The cold install process erases the pre-existing operating
system and data and then installs the new operating system and software; you must
then restore the data. The advantage of migrating with cold install is that the software
can be installed without regard for the software currently on the system or concern for
cleaning up old software.
A significant factor when deciding to either do an upgrade or cold install is overall system
downtime. A rolling upgrade will cause the least downtime. This is because only one
node in the cluster is down at any one time. A non-rolling upgrade may require more
down time, because the entire cluster has to be brought down during the upgrade
process.
One advantage of both rolling and non-rolling upgrades versus cold install is that
upgrades retain the pre-existing operating system, software and data. Conversely, the
cold install process erases the pre-existing system; you must re-install the operating
system, software and data. For these reasons, a cold install may require more downtime.
The sections in this appendix are as follows:
167