Pre-Upgrade Sanity Check Tool

The purpose of this tool is to check for all known issues that can cause an upgrade to fail. We'll use learnings from customer upgrade failures to continue improving this sanity tool. Ideally if something is fixable automatically, the tool would fix it, if not at least call out the issues requiring manual resolution and suggesting not to upgrade or potential risk of upgrading.

When this tool is run is TBD, either manually before, or automatically as part of the upgrade packages. A watermark, log entry should be created in messages or debug.log indicating it was run so that support can verify that the customer followed the recommended procedures/checks before upgrading.

Ideas of possible checks: HMV's and lbids described in extent map exist/valid on disk for each table/extent (i.e every table is writable before upgrading, extent map checker searching for orphaned files on disk, table_checker making sure all table are selectable before upgrading etc.