Oracle ASM Disks Not Visible After Reboot - Diagnosis and Fix
Problem Overview After a scheduled reboot of a RHEL 8 server running Oracle ASM, the Oracle instance failed to start. Investigation revealed that ASM disks were not visible under /dev/oracleasm , and oracleasm listdisks returned no results. Initial Diagnosis Symptoms Observed: cd /dev/oracleasm ls # → No output oracleasm status # Checking if ASM is loaded: no # Checking if /dev/oracleasm is mounted: no oracleasm scandisks # Unable to instantiate disk "MIM_DATA_QA_ORC05_01" oracleasm listdisks showed no known disks. Deep-Level Checks Confirmed disk devices present using lsblk (e.g., /dev/sde1 , /dev/sdf1 , etc.) Kernel module oracleasm not loaded ( lsmod | grep oracleasm returned nothing) Root Cause Identified The Oracle ASM kernel module ( oracleasm ) was not auto-loaded after reboot, preventing ASMLib from recognizing ASM disks. Resolution Steps Reinstalled ASMLib kernel ...