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Challenges/Requirements for Upgrade/Rollback
Based on the discussion above, a solution to the upgrade/rollback
problem requires specific capabilities:
- An upgrade/rollback solution should not require excessive change
from existing processes for the distribution and installation of
software.
- A solution must enable software rollback with minimal operator
intervention. Ideally, when an operator initiates the rollback
procedure, the system automatically reverts all necessary state,
such as program files, configuration files, etc.
- The upgrade and rollback procedures should operate quickly.
- The solution should minimize
the down time due to upgrades and rollbacks. Note that this
requirement can be relaxed for applications such as a web server
cluster, because the application architecture itself can compensate
for the unavailability of individual service nodes.
Note that the third and fourth requirements are not equivalent. It
might be possible, for example, to minimize down time by running the
upgrade procedure ``in the background''. But this might conflict with
the goal of upgrading the software quickly.
mukesh agrawal
2003-06-17