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Given that software is often distributed as packages, and managed by
package management systems, such as the Redhat Package Manager,
a natural approach is to leverage
these systems to manage software updates and rollbacks. Our upgrade
procedure might be as follows: shut down the service, copy system
configuration files, upgrade the software (taking care to log the
prior version of the upgraded software), and
then restart the service. The rollback procedure would be to shut down
the service, remove the upgraded software, reinstall prior versions,
restore configuration files, and then restart the service.
This approach well achieves the first and second goals of Section 2.2. Depending
on the number of packages involved in an upgrade,
and the complexity of their installation scripts, however, the
corresponding rollback operation may take some time to complete. Thus
the approach may not achieve the third goal.
mukesh agrawal
2003-06-17