How to resolve IO errors after restarting Oracle ASM?

After restarting Oracle ASM, if there is an IO error, you can try the following solutions:

1. Check the storage device connection to ensure that the connection between the storage device (disk group) and the ASM instance is working properly. Make sure that the power and data cables of the storage device are properly connected.
2. Check the ASM disk status by using the ASM command to query the disk status, for example: SELECT PATH, STATE FROM V$ASM_DISK; and make sure the disk status is ONLINE.
3. Check the status of the ASM disk group: Use the ASM command to query the disk group status, for example: SELECT NAME, STATE FROM V$ASM_DISKGROUP; make sure the disk group status is ONLINE.
4. Check the ASM instance logs: Review the log files of the ASM instance, such as $ORACLE_BASE/diag/asm/+asm/asmtrace/alert_+ASM.log, and search for keywords like IO error, disk error, etc. to identify specific error messages.
5. Check the operating system logs: Review log files for the operating system, such as /var/log/messages (Linux) or /var/adm/messages (AIX), and search for keywords like IO error, disk error, etc. to identify specific error messages.
6. Check the status of disk devices: Use operating system commands to check the status of disk devices, such as lsblk (Linux) or lspv (AIX), to ensure the disk devices are functioning properly.
7. Check ASM parameter configuration: Ensure that the parameters of the ASM instance are correctly configured, especially those related to disk groups and disks, such as ASM_DISKGROUPS and ASM_DISKSTRING.
8. Attempt to restart the ASM instance: If the above methods do not solve the issue, you can try restarting the ASM instance by connecting to it with SQL*Plus and executing the commands SHUTDOWN IMMEDIATE and STARTUP.

If the above methods still cannot solve the issue, it is recommended to contact Oracle technical support or consult with a professional database administrator for further troubleshooting and repair.