To enable IO 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.
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.
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.
Whenever the sg driver is loaded at system 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.
