Data disks are standard disk devices used for data storage. These can be physical disks or RAID Logical Units (LUNs). These disks must support SCSI-3 PGR. Data disks are incorporated in standard VxVM/CVM disk groups. CVM is responsible for fencing data disks on a disk-group basis. Because VxVM enables I/O fencing, several other features are also provided. Disks added to a group are automatically fenced, as are new paths to a device.