A physical disk is the basic storage device (media) where the data is ultimately stored. You can access the data on a physical disk by using a device name to locate the disk. The physical disk device name varies with the computer system you use. Not all parameters are used on all systems.

Figure: Physical disk example shows how a physical disk and device name (devname) are illustrated in this document.

In HP-UX 11i v3, disks may be identified either by their legacy device name, which takes the form c#t#d#, or by their persistent (or agile) device name, which takes the form disk##.

In a legacy device name, c# specifies the controller, t# specifies the target ID, and d# specifies the disk. For example, the device name c0t0d0 is the entire hard disk that is connected to controller number 0 in the system, with a target ID of 0, and physical disk number of 0. The equivalent persistent device name might be disk33.

In this document, legacy device names are generally shown as this format is the same as the default format that is used by the Device Discovery Layer (DDL) and Dynamic Multi-Pathing (DMP).

VxVM writes identification information on physical disks under VxVM control (VM disks). VxVM disks can be identified even after physical disk disconnection or system outages. VxVM can then re-form disk groups and logical objects to provide failure detection and to speed system recovery.

VxVM accesses all disks as entire physical disks without partitions.