Data is stored somewhere

Trigger RMAN Archivelog Backups Based on Filesystem Usage

Apr 21, 2005

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A rapidly growing archive destination can fill during bulk loads or data migrations. A usage-triggered RMAN job is a useful emergency backstop, but it should complement—not replace—scheduled archivelog backups, monitoring, and capacity planning.

If you use the fast recovery area

Measure the Oracle-managed recovery area from the database rather than parsing a filesystem command:

SELECT name,
       ROUND(space_used * 100 / NULLIF(space_limit, 0), 1)
         AS percent_used,
       ROUND(space_reclaimable * 100 / NULLIF(space_limit, 0), 1)
         AS percent_reclaimable
FROM   v$recovery_file_dest;

V$RECOVERY_AREA_USAGE breaks the total down by archived logs, backup pieces, flashback logs, and other file types.

If archives use a normal filesystem

Read the active archive destination from the database configuration, then check that exact mount with the operating system’s supported disk-usage tool. Do not assume the obsolete LOG_ARCHIVE_DEST parameter is the only destination; modern systems commonly use LOG_ARCHIVE_DEST_n.

RMAN command

RUN {
  SQL 'ALTER SYSTEM ARCHIVE LOG CURRENT';
  BACKUP ARCHIVELOG ALL
    NOT BACKED UP 1 TIMES
    DELETE INPUT;
}

DELETE INPUT removes only the archived-log copy that RMAN successfully backed up. With multiple archive destinations, use the deletion behavior appropriate to the redundancy and Data Guard policy.

Automation safeguards

Use operating-system or Oracle Wallet authentication; never embed a recovery-catalog password in a world-readable script.
Use a lock so two threshold checks cannot start overlapping RMAN jobs.
Write logs to a protected directory and alert on any nonzero RMAN exit status.
Set warning and critical thresholds with enough headroom for the backup to finish.
Confirm that archived logs required by standby databases or downstream consumers are not deleted prematurely.
Test a restore of the archived-log backups.

Reference

Oracle’s RMAN command quick reference includes BACKUP ARCHIVELOG ALL DELETE INPUT.