You should monitor the response time of the quorum disks regularly using Export Tool 2 on the primary or secondary storage system to detect possible issues.
If the response time from the external storage system for quorum disks is delayed for more than one second, GAD pairs might be suspended by some failures. If the response time exceeds 100 ms, review the configuration and consider the following actions:
- Lower the I/O load, if the I/O load of volumes other than the quorum disk is high in the external storage system.
- Remove the causes of the high cache load, if the cache load is high in the external storage system.
- Lower the I/O load of the entire external storage system, when you perform maintenance of the external storage system. Alternatively, perform maintenance on the external storage system with settings that will minimize the impact to the I/O, referring to the documentation for the external storage system.
If the health check process for the Quorum disk fails within 15 seconds, the Quorum disk will be blocked. Normally, the health check process times out after 3 seconds and is retried after ABTS processing, but setting SOM 1080 to ON changes the timeout period for ABTS processing to 15 seconds. If ABTS processing times out, the health check process cannot be retried on a redundant path, resulting in the Quorum disk being blocked.
When ABTS processing times out, a logout process is performed on a per-port basis, causing all ongoing processes on the same path to be interrupted. Therefore, if the external path for the Quorum disk is shared for other purposes such as host I/O, it will also affect I/O other than the health check process. If you want to reduce this risk when using the external path for the Quorum disk in conjunction with other purposes like host I/O, set SOM 1080 to ON. However, if there is a problem with the path, there is a risk that the health check process cannot be retried on a redundant path and the Quorum disk will be blocked. If you want to avoid blocking the Quorum disk, set SOM 1080 to OFF.