Using Serviceguard Extension for RAC, 4th Edition, February 2007

Software Upgrades
Appendix A 215
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.