OpenVMS UDID Support

Each OpenVMS fibre-attached volume requires a user-defined identifier or unit device identifier (UDID). This section describes how you define a UDID for each storage unit volume.

This is a nonnegative integer that is used in the creation of the OpenVMS device name. All fibre-attached volumes have an allocation class of $1$ , followed by the letters, DGA, followed by the UDID. All storage unit LUNs that you assign to an OpenVMS system need an UDID so that the operating system can detect and name the device. LUN 0 also must have an UDID; however, the system displays LUN 0 as $1$GGA<UDID>, not as $1$DGA<UDID>. See the HP document, Guidelines for OpenVMS Cluster Configurations for more information about fibre attached storage devices.

You can use the IBM^® System Storage™ DS Storage Manager or the DS CLI to set a value in a storage unit volume name field that is used by AlphaServer systems as the UDID for the volume. (In this document, we provide DS CLI examples.) You can find the DS CLI on the CD that you receive with the storage unit. See the IBM System Storage™ DS6000™ Command-Line Interface User's Guide for more information.

The DS CLI is a general purpose utility that supports various storage unit functions. The DS CLI allows 16 alphanumeric characters as input when you complete the storage unit volume name field. OpenVMS UDID values must be an integer within the range of 0 to 32767. Therefore, you must ensure that the input is valid for UDID support. The utility does not enforce UDID rules. It accepts values, such as AaBbCcDd, that are not valid for OpenVMS. It is possible to assign the same UDID value to multiple storage unit volumes. However, each volume that you assign to an OpenVMS system must have a value that is unique for that system or throughout the OpenVMS cluster to which that system belongs. Review the HP OpenVMS documentation for UDID rules, and verify that your input is valid.

Note: Volumes with UDIDs greater than 9999 cannot be MSCP-served in an OpenVMS cluster to other systems.

The following example uses the DS CLI to add or change a name to an existing DS volume. In the example the DS CLI is in interactive mode and a configuration profile file has been defined. The final command uses the AlphaServer console to list fibre attached volumes.

Use the chfbvol command to change the name of a fixed block volume: For example to set the UIDD value to 21, type: chfbvol -name 21 0001
The value for the name parameter in the DS CLI command is the UDID field for the HP AlphaServer. This command returns the volume ID. The following is example output:
```
CMUC00026I chfbvol: FB volume 0001 successfully modified.
```
Note: The first volume, LUN 0, will be reported as a CCL device, and not as a disk volume.
To make a volume group called “VMS_A0” and add a volume to it, type: mkvolgrp -type scsimap256 -volume 0001 VMS_A0
This command returns the volume group ID. The following is example output:
```
CMUC00030I mkvolgrp: Volume group V0 successfully created.
```
To create an OpenVMS host with the DS CLI and associate a volume group with it, type: mkhostconnect -wwname 10000000ABCDEF98 -hosttype HpVms -volgrp v0 ES40_A
This command returns the host connection ID. The following is example output:
```
CMUC00012I mkhostconnect: Host connection 0005 successfully created.  
```

To display the defined attributes for a host connection, type: showhostconnect 0005

The following is example output:

Name          ES40_A
ID            0005
WWPN          10000000ABCDEF98
HostType      HpVms
LBS           512
addrDiscovery LUNPolling
Profile       HP - Open VMS
portgrp       0 volgrpID
V0 atchtopo      -
ESSIOport     all

To display the volumes in a volume group, and, its attributes, type:showvolgrp v0
The following is example output:
```
Name VMS_A0
ID   V0
Type SCSI Map 256
Vols 002A 0000F 0001
```
Use the wwidmgr -show wwid command at the AlphaServer console to list fibre attached volumes that have been detected by its fibre-channel host adapters. If a volume has no UDID or has an invalid UDID, the volume UDID is minus one (-1). When it is booted, OpenVMS does not detect a volume with -1 as a UDID number. Confirming fibre-channel switch connectivity for OpenVMS in section "Confirming fibre-channel switch connectivity for OpenVMS" shows this in detail.