An update process can keep a verified version available until a replacement passes its checks. If the replacement fails, the system can restore the earlier version or switch traffic back to it.
Software and data may need different recovery steps. A program might be easy to replace while a database change requires its own recovery procedure.
ELI5
A rollback puts a system back the way it was before a change went wrong.
Imagine trying a new layout for a document and keeping the previous version. If the new layout breaks the page, you can restore the saved version.
Does a rollback always undo data changes?
Only when the recovery procedure covers those changes. Restoring older software may leave data written by the new version in place.
When should a rollback happen?
Teams can define checks for failed updates and restore the last known working state when those checks show a problem.
