Preparing to Set Up I/O Fencing

Enable I/O fencing.

1. To enable I/O fencing on Linux, use operating system commands to load a SCSI generic (sg), driver on each node running the shared-disk cluster. Loading the driver automatically creates /dev/sg* files.
2. Grant read and write permission to each instance for all /dev/sg* files created on that node by the sg driver.
   For example, if the database device on the raw partition /dev/raw/raw1 is mapped to /dev/sg3, grant write permission on the /dev/sg3 file.
3. Make sure the Cluster Edition has write access to /dev/sg files that correspond to configured database devices. In addition, the fence device must have write access to /dev/sg files containing SCSI-3 PGR commands.
   The path for the fence device may be different from the corresponding physical device path. For example, the database device might be /dev/raw/raw1, the physical device /dev/sda, and the fence device /dev/sg0.
   Note: Whenever the sg driver is loaded during startup (or through user command), the system re-creates the /dev/sg* files. Make sure that permissions are granted appropriately on these files as part of the startup process. Otherwise, the system administrator must manually reset permissions each time the system starts.