By default, if the service domain that provides access to a virtual SAN is unavailable, all I/O from the guest domain to the corresponding virtual SCSI HBA is blocked. The I/O is resumed automatically when the service domain becomes operational and restores service to the virtual SAN.
Sometimes, file systems or applications might require an I/O operation to fail and report an error if the service domain is unavailable for too long. You can set a connection timeout period for each virtual SCSI HBA to establish a connection between the virtual SCSI HBA on a guest domain and the virtual SAN on the service domain. When that timeout period is reached, any pending I/O and any new I/O operations fail as long as the service domain is unavailable and the connection between the virtual SCSI HBA and the virtual SAN is not re-established.
Other circumstances in which you might want to specify the timeout value include the following:
If you want MPxIO to fail over to another configured path, you must set the timeout for each virtual SCSI HBA involved.
If you perform a live migration, set the timeout property value to 0 for each virtual SCSI HBA in the guest domain to be migrated. After the migration completes, reset the timeout property to the original setting for each virtual SCSI HBA.
To find out how to set the timeout value, see Setting the Virtual SCSI HBA Timeout Option.