General overview
A patch is a deployable unit (DU), or set of DUs, which replace existing DUs of the same name in a Rhino node in order to fix a bug where it is infeasible for the operator to wait for the next release. See Patching tools overview for more information about the tools and how they work.
A minor upgrade is a new revision of the product software, indicated by an increment to the final part of the version number (e.g. 2.7.0.6 → 2.7.0.7). It will contain bugfixes, new features and new configuration for the new features. But the configuration is always backwards compatible.
A major upgrade is a new version of the product software, indicated by a change to any of the first three parts of the version number (e.g. 2.7.0.6 → 2.8.0.0). It will contain bugfixes and new features. Unlike minor upgrades or patches, it may also contain new configuration models (profiles and profile tables) and/or changes to existing profiles and tables schemas. This makes the upgrade process more complex compared to minor upgrade.
For an overview of upgrade see Upgrades Overview.
Since Rhino uses the cluster’s database to replicate DUs between all members of the cluster, it is only necessary to actually apply the patch or upgrade on one node; but all nodes must be migrated to the new cluster which will be created when the patch or upgrade is applied to the first node.
Rolling patch or upgrade is the procedure that allows the current Sentinel product to handle telecom signaling while it is being patched or upgraded.
orca is the tool that allows rolling patches and upgrades. It does that by implementing Cluster Migration Workflow.
All operations can be rolled back (undone), but patches differ from upgrades in that they can also be reverted. To revert a patch is to replace the DUs with the originals (the original DUs are included in the patch file), but without migrating back to the downlevel cluster. This can be useful, for example, to preserve configuration changes that were required as part of the patch in the case where the patch will be applied again in the near future.
