Openvms Lun 0 - Command Control Lun; Confirming Fibre-Channel Switch Connectivity For Openvms - IBM TotalStorage DS6000 Attachment Manual

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OpenVMS LUN 0 - Command Control LUN

Confirming fibre-channel switch connectivity for OpenVMS

48
DS6000 Host Systems Attachment Guide
Name VMS_A0
ID V0
Type SCSI Map 256
Vols 002A 0000F 0001
6. 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
number is minus one (-1) or zero (0). When it is booted, OpenVMS does not
detect a volume with -1 or 0 as a UDID number.
The storage unit assigns LUN numbers using the lowest available number. The first
storage unit volume that is assigned to a host is LUN 0, the next volume is LUN 1,
and so on. When a storage unit volume is unassigned, the system reuses the LUN
number that it had when assigning another volume to that host.
To be compatible with OpenVMS, the storage unit volume that becomes LUN 0 for
an OpenVMS system is interpreted as the Command Console LUN (CCL), or
pass-through LUN. The storage unit does not support CCL command functions.
This storage unit volume (LUN 0 for OpenVMS) does not display when you issue
the wwidmgr -show wwid AlphaServer console command. When OpenVMS is
running and a UDID has been set for that storage unit volume, the storage unit
volume LUN 0 displays as a GGA device type, not as a DGA device. Although
OpenVMS does not strictly require a UDID for the CCL, the SHOW DEVICE command
displays CCL device creation if you set a UDID. You can display the multiple paths
and diagnose failed paths to the storage controller using the SHOW DEVICE/FULL
command.
Guidelines: The first storage unit volume that you assign to an OpenVMS system
can become LUN 0. However, the volume that you assign must be used by the
system for only support capability and must be at the minimum size. A host cannot
use the volume for any other purpose. Multiple OpenVMS hosts, even in different
clusters, that access the same storage unit, can share the same storage unit
volume as LUN 0, because there will be no other activity to this volume.
At the AlphaServer console, when you issue the wwidmgr -show wwid command,
LUN 0 does not display. Only fibre-channel storage devices are listed in the output.
The storage unit LUN 0 is presented as a CCL device, and therefore, is not shown.
This section lists the steps you must perform to confirm fibre-channel switch
connectivity for the OpenVMS host system.
1. Open a telnet session and log in to the switch as an administrator.
2. Confirm that each host adapter has performed a fabric login to the switch.
Figure 27 on page 49 shows an example of what displays when you type the
switchshow command.
3. Confirm that each storage unit host adapter has performed a fabric login to the
switch. Figure 27 on page 49 shows an example of what displays when you
type the switchshow command.