Resolving Oracle ASM Disk Configuration Issues After Node Reboots

Problem Summary:

Each time Node B is rebooted, two disks fail to automatically configure in Oracle ASM (Automatic Storage Management). These disks—ORA01_DSK2 and ORA01_DSK3—require manual intervention to be configured correctly after the system starts. This issue is evident from the output of the oracleasm scandisks command, where these disks are listed as valid but need to be instantiated manually.

Even though the disks are recognized as valid ASM disks, they are not automatically configured during the boot process, requiring the execution of oracleasm scandisks manually to bring them online.

Diagnosis:

Several potential causes could explain this issue:

1. Service Dependency Misconfiguration: The Oracle ASM service (oracleasm.service) might be starting before the udev service, which manages device initialization, completes its work. This would result in some disks not being available when ASM performs its scan.
2. Disk Initialization Timing: Some disks may take longer to be detected by the system, causing them to be unavailable when Oracle ASM performs its automatic scan.

Solution Applied:

To address the problem, the following changes were made to the oracleasm service configuration:

1. Modifying the oracleasm Service: The configuration file for the Oracle ASM service (/etc/systemd/system/multi-user.target.wants/oracleasm.service) was updated to ensure that Oracle ASM starts after the udev service has fully initialized all devices. The following line was added to the configuration:

   After=systemd-udevd.service

   This ensures that the system’s disks are available by the time Oracle ASM performs its scan.

2. Adding a Startup Timeout: A 120-second startup timeout was added using the TimeoutStartSec=120s directive. This allows Oracle ASM enough time to detect and configure all disks properly, even if disk initialization takes longer than usual. This prevents ASM from failing due to delayed disk recognition.

Conclusion:

By modifying the Oracle ASM service to depend on udev and increasing the timeout for service startup, the issue of disks not being automatically configured after a reboot was resolved. This solution ensures that all ASM disks are properly recognized and configured during the boot process, eliminating the need for manual configuration.