Request for improved recovery options

Other Ideas for different product enhancements/feature request based on customer experience.

Other Tickets:

• make periodic copies of the BRM_saves_journal - Brm_saves should keep A & B copies of the BRM_saves_journal to reduce the timeframe of dataloss and/or load_brm should attempt more auto recovery options with its own saves A & B files (MCOL 5820)

• debug utility to cleanup extent map (BRM_saves_em) - a debug utility should exist to find orphaned objects/ extent files to either delete them ( support em check script + MCOL-5781)

UPDATE: DONE

• Rebuild EM should work with S3 clusters - currently only works with single node deployments if it has access to all dbroots (meaning non-ha clusters is complicated to use or not possible)

UPDATE: WONT DO

• Rebuild EM doesnt exist in CS 5- currently only works in CS 6+ and has no official documentation
• maxscale should work with cmapi- Putting a node in maintenance mode in maxscale should work with cmapi or cmapi should notice the maintenance flag and safely remove the node from the columnstore cluster

Current Rebuild EM Notes
Internal Link: https://mariadbcorp.atlassian.net/wiki/spaces/Support/pages/1576632337/Rebuild+the+extent+map