(Requires immediate investigation to prevent data loss or service disruption) Potential Causes & Findings Disk Group Dismount
The error message indicates that the Oracle Automatic Storage Management (ASM) instance has detected a critical hardware or software problem, most commonly resulting in an unplanned disk eviction or forced diskgroup dismount . When this alert triggers in your ASM alert log, it usually means ASM can no longer read from or write to one or more physical storage devices. Immediate action is required to prevent a full Cluster Ready Services (CRS) crash or database downtime. What Causes the ASM Health Checker Failure?
To fix the error, you must first uncover exactly what the Health Checker discovered. Follow this step-by-step triage workflow. Step 1: Locate the Diagnostic Report
Before digging into the logs, you need to assess the immediate risk to your production environment. asm health checker found 1 new failures
Query the V$ASM_DISK view to check disk headers.
: In "External Redundancy" disk groups, the failure of even a single disk causes the entire group to fail. Disk Header Corruption
(Invoking related search terms tool for People/Places/Shopping/etc. is not needed here.) (Requires immediate investigation to prevent data loss or
After the repair and any subsequent rebalance operation are complete, re-run the diagnostic CHECK command without the REPAIR clause.
In cloud or virtualized infrastructure, an underlying network flap can interrupt multipath software (e.g., Device Mapper Multipath). If all redundant paths to a LUN drop simultaneously, ASM interprets this block-level device vanishing act as a device failure. ASM-ALERTLOG-Output-Failure-CELLI03-and-CELL01
This article provides a 360-degree breakdown of this alert: what triggers it, how to diagnose the root cause, step-by-step repair procedures, and long-term prevention strategies. What Causes the ASM Health Checker Failure
-- Check overall disk group status SELECT name, state, type, total_mb, free_mb, required_mirror_free_mb, usable_file_mb FROM v$asm_diskgroup;
-- Check detailed status of all disks in all disk groups SELECT group_number, disk_number, name, path, state, mode_status, header_status, total_mb, free_mb FROM v$asm_disk;
Grep the ASM logs for the timestamp of the failure.