IBM System storage DS6000 Series, Attachment Manual

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Multiple OpenVMS systems can access the same storage unit adapter port.
However, you must define each system for that specific storage unit port and
assign at least one storage unit volume.
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To re-enable compatibility, you can force the defined OpenVMS host to
reestablish connectivity to the storage unit adapter by disabling the switch port it
is connected to, and then enable the switch port again.
Troubleshooting fibre-channel attached volumes for the OpenVMS host
system
This section contains a few examples of issues that can occur with your OpenVMS
host system and some suggestions to correct the issues.
Problem
The following communication problems might occur when you attach a storage unit
to an HP AlphaServer OpenVMS host system.
Investigation
If the system hangs during boot
Your system might be attempting to access a host adapter port that is not
configured for it. To correct your system, check to ensure that the following
items are true:
1. The fibre-channel switch is enabled to ensure zoning.
2. The zones for the OpenVMS host are connected to only those ports that
are correctly configured to support them.
3. Other fabric zones do not include the OpenVMS host adapters by
mistake.
If the system reaches the mount verification timeout
All pending and future I/O requests to the volume fail. You have to dismount
and remount the disk before you can access it again.
The mount verification process for fibre attached volumes might not
complete until the system reaches the mount verification timeout. This can
be caused by the same scenario that causes the system to hang during
boot. Verify that the path to the affected volumes is available, and then
follow the above list.
If another host system gains access to a storage unit host adapter port that is
dedicated for OpenVMS
The port will have its compatibility mode disabled. This can occur when the
fabric switch has disabled all zoning. After you reenable zoning, the storage
unit port compatibility remains disabled. Some internal storage unit
processes cause a momentary loss of connectivity to volumes with activity
I/O. OpenVMS has no problems when the storage unit adapter port is in
compatibility mode. If the mode is disabled, disk I/O could fail a read or
write and display the following message:
-SYSTEM-F-TOOMANYRED, too many redirects
Force the host adapter to reestablish connectivity
Forcing the OpenVMS host adapter to reestablish fibre-channel connectivity
with the storage unit adapter port will enable compatibility mode. You can
force the connection only by disconnecting and then reconnecting one end
of the physical fibre-channel cable between the host and the affected
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DS6000 Host Systems Attachment Guide