AWR report shows "Disk File Mirror Read" in the Top 5 Timed Foreground Events
(Doc ID 1913253.1)
Last updated on FEBRUARY 21, 2019
Applies to:Oracle Database - Enterprise Edition - Version 188.8.131.52 to 184.108.40.206 [Release 11.2 to 12.1]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
The "Disk file Mirror Read" waits are observed in the Top 5 Timed Foreground Events section of the AWR report, like this:
To see this symptom all of the following must be true:
- RAC database
- Control file(s) in a normal or high redundancy ASM disk group
- Minimum database version
- 220.127.116.11.11 Database Patch Set Update
- 18.104.22.168 Bundle Patch 20 for Exadata Database
- 22.214.171.124 Patch 32 on Windows Platforms
- 126.96.36.199 (Server Patch Set)
- 188.8.131.52 (Base Release)
There was a code change to do with the mirrored controlfiles, that results in the increased wait count of the "Disk file Mirror Read" event.
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