8.5.13 Rolling Back Updates

A backup enables you to roll back updates, regardless of whether the update failed or succeeded. This backup is stored on the inactive system partition, as described in "Backing up Exadata Database Servers Before Planned Maintenance". Because Exadata systems have only one inactive system partition, the rollback operation can only revert to the previous active image.

When rolling back an update, the update utility performs the following actions:

• Shuts down the stack and domU’s.
• Deactivates the active system partition, and activates the inactive system partition.
• Restores /boot from the inactive partition.
• Updates the grub boot-loader.

Note:

Before performing a rollback operation on an Exadata Database Server, consider that the rollback procedure is designed to revert changes made by a patch or system update but does not account for subsequent changes to the system.

A rollback will likely run into problems if the system contains post-update customizations to system files, especially those in /etc, connected in any way to Oracle Database and Oracle Grid Infrastructure (GI).

If your system contains customizations to system files, rehearse the rollback on a test system to discover issues and develop specific workarounds for them.

You can always reduce the risk of unforeseen issues during rollback operations by adhering to Exadata system configuration and customization best practices and carefully following the available product documentation (including update-specific release notes and README files).

Example 8-19 Rolling back an update using patchmgr

[root@pmserver ]# ./patchmgr --dbnodes dbs_group --rollback

--dbnodes specifies the list of database nodes to be updated.

--rollback specifies the rollback action.

For more options see the update utility’s built-in help.

Note:

Firmware updates are not rolled back when rolling back to a previous image. The Oracle Exadata System Software releases support later firmware releases. After rolling back, run the following commands to apply older firmware versions when needed:

# /etc/init.d/lsidiag stop

# /etc/init.d/lsi_mrdsnmpd stop

# /opt/oracle.cellos/CheckHWnFWProfile -action updatefw -mode exact

The CheckHWnFWProfile command is available in Oracle Exadata System Software releases starting with 11.2.3.3.0.