Oracle Database / Storage, Undo & Redo
Inspect redo groups before planning a log maintenance change
Redo groups have lifecycle states that determine whether a change is safe. Inspect group status, size and archival state before touching files.
Environment and inputs: Oracle Database 19c baseline · SQL*Plus-compatible SQL unless RMAN, DGMGRL, ADRCI or a host shell is specified. Check release, patch level, edition and container first.
Start with this diagnostic
Use the stated SQL, RMAN, DGMGRL or host shell and replace sample names with approved targets. DBA and V$ views need authorized catalog access in the correct container. Do not grant broad privileges for an example.
SELECT group#, thread#, bytes, members, archived, status FROM v$log ORDER BY thread#, group#;Read the result
CURRENT, ACTIVE and INACTIVE have different recovery implications. ARCHIVED status must be interpreted with database mode and checkpoint progress.
Resolve and verify
Compare groups with switch frequency and recovery requirements. Plan any resize or replacement using the documented add-and-switch maintenance procedure.
Operational precautions
Never delete online redo files at the OS level or clear a group needed for recovery.