HP-UX 11i v3 Device Special File (DSF)

In a similar way to hardware paths, there are two types of DSFs for mass storage: legacy DSFs and persistent DSFs. Both can be used to access a given mass storage device independently, and can coexist on a given system. These DSFs are described below.

A legacy device special file was the only type of mass storage DSF in releases prior to HP-UX 11i v3, so it is associated with the legacy view. It is locked to a particular physical hardware path, or lunpath, and does not support agile addressing. Each lunpath requires a different DSF, so a multi-pathed LUN has multiple DSFs, one for each lunpath.
A persistent device special file is associated with a LUN hardware path, and is seen in the agile view. Because it is based on the LUN hardware path, rather than the lunpath, it transparently supports agile addressing and multipathing. Like the LUN hardware path, the binding of device special file to device persists across reboots, but is not guaranteed to persist across installations.

Device Files: Installing and Updating

If you cold-install HP-UX 11i v3, both legacy and persistent DSFs are automatically created. By default, the installation process will configure system devices like the boot, root, swap, and dump devices to use persistent DSFs. This means that configuration files such as/etc/fstab, /etc/lvmtab, and others will contain references to persistent DSFs.

If you update from HP-UX 11i v2 to 11i v3, existing legacy DSFs are retained, and persistent DSFs will be created.

In addition, legacy DSFs are completely backward compatible, and will not be affected by any persistent DSFs on the same server. A device can be simultaneously accessed via legacy and persistent DSFs. For more information on the new mass storage stack, see the whitepaper called, The Next Generation Mass Storage Stack: HP-UX 11i v3 at:

http://docs.hp.com/

HP-UX 11i v3 Device Special File (DSF)

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Device Files: Installing and Updating