HP-UX Input and Output

Legacy Device Special Files

Persistent Device Special Files

With legacy device special files, if you move the device associated with them (logically or physically) you will need to address those devices via new or different device special files. This is because the device special files are associated with the physical path to the device (the sequence of internal components that data must travel). If any part of the path changes, a different device special file is needed.

Persistent device special files are instead associated with a unique address on the device (known as a worldwide identifier — WWID) rather than the path to the device. This means that even if the path to the device changes, no changes are needed to the device special files associated with that device.

Persistent device special files are only associated with mass storage devices. Generally these are disk drives, some tape drives, and similar mass storage devices.

For non-mass storage devices, the traditional form of device special files (based on hardware paths as with legacy device special files for mass storage devices) still applies.