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Appendix B: Device Special File Naming Model

HP-UX 11i v3 introduces a new representation of mass storage devices called the agile view. In this

representation, the device special file (DSF) name for each disk no longer contains path (or link)

information. There are two DFS types:

 The multipathed disk has a single persistent DSF regardless of the number of physical paths to it.

 The legacy view, represented by the legacy DSF, continues to exist.

You can use both DSF types to access a given mass storage device independently, and both can

coexist on a system.

While LVM supports the use of both DSF naming models within the same volume group, you can

configure the volume group to use both styles of DSFs: on a given system, some volume groups can

use legacy DSFs, others persistent DSFs, and the remaining can use a mix of persistent and legacy

DSFs. Supporting a mixed mode configuration allows a volume group that currently uses one DSF

naming model to be extended to include a different DSF naming model (see vgextend(1M) for more

information). Any such configuration results in a mixed mode volume group. Mixed mode facilitates a

phased migration from legacy to persistent naming model.

HP recommends using persistent DSFs for LVM configurations and encourages configuring new

volume groups using persistent DSFs. To fully utilize all the capabilities of the new mass storage stack,

HP recommends migrating volume groups from legacy DSFs to persistent DSFs. HP provides

/usr/contrib/bin/vgdsf to facilitate this migration. This script works for both root and non-root

volume groups. See the For More Information section in the LVM Migration from legacy to persistent

naming model white paper for more details.

Most of the LVM commands are backward compatible, and work transparently with both legacy and

persistent DSFs. New options have been added to the vgimport(1M) and vgscan(1M) commands, to

appropriately choose the required DSF naming model.

Starting with the HP-UX 11i v3 release, HP recommends using persistent DSFs for LVM configurations

and advises you to configure all new volume groups using persistent DSFs. To verify if the legacy

naming model is enabled on a system, use the insf(1M) command. To disable the legacy naming

model, use rmsf(1M). Note that to configure new volumes groups using persistent DSFs, you do not

need to disable the legacy naming model (which removes all legacy I/O nodes and their device

special files on the system). The rmsf command does not complete successfully if any legacy I/O

nodes are in the open state. If this is the case, the command fails and returns information, such as

process name (PID) and the device special file, about the processes that have opened the legacy I/O

nodes.

For more information on the benefits of migration, see The Next Generation Mass Storage Stack white

paper.

This appendix lists the new options that were added to some LVM commands to specify the

preference of DSF naming model. Also, it lists the behavioral differences of commands for each

message, the cause is listed, and an administrator action is recommended. The appendix is divided

into two sections, one for the new options provided to specify the DSF naming model and one for the

behavioral differences of commands after disabling the legacy naming model.

New Options to Specify the DSF Naming Model

Most LVM commands are transparent to the DSF naming model used, bit new options were added to

the vgimport(1M) (option -N) and vgscan(1M) (options –N and –B) commands to specify the

preference of DSF naming model. These options are detailed in their respective manpages, but are

summarized in the following table:

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