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A Troubleshooting
This appendix describes some common issues you may encounter while configuring the VLS.
Common issues
Symptom
Some of the virtual
devices are not detected
by the operating system
when it scans the SAN
for new hardware.
Possible causes
There are more LUNs on the FC
host ports than the operating system
is configured to see. Once the
maximum number of LUNs on a
device is detected, the operating
system stops looking for more
LUNs. In the case of the VLS, the
operating system considers each FC
host port to be one device. So, if
the maximum number of LUNs an
operating system is configured to
see is eight, the operating system
will only see LUN0, LUN1, ..., LUN7
and will not see LUN8, LUN9, ...,
and up on each FC host port. By
default Windows and HP-UX hosts
can see a maximum of 8 LUNs per
FC host port.
There is a gap in the LUN numbering
on the FC host port. Most operating
systems will stop looking for virtual
devices on a FC host port once
a gap in the LUN numbering is
detected. For example, say LUN0,
LUN1, and LUN3 are mapped to a
FC host port. The operating system
will see LUN0 and LUN1, but when it
does not find a LUN2, it will assume
there are no more LUNs on the port
and stop looking.
Solution
Increase the maximum number of
LUNs per device the operating
system is configured to see. To
change the maximum LUN per
device setting:
•
Microsoft Windows—See
http://support.microsoft.com/
default.aspx?scid=kb%3ben-
us%3b310072.
•
HP-UX—The value cannot be
changed.
•
Other operating systems—See
the operating system web site.
Use the VLS's LUN masking feature
to restrict the number of virtual
devices the host sees on the VLS
FC host port(s), so it only sees the
virtual devices it needs to see. Then,
use the VLS's LUN mapping feature
to assign LUNs to the virtual devices
the host can see, such that the
virtual device LUN numbers include
a LUN0 and no gaps in the LUN
numbering. See
LUN masking
LUN mapping
for instructions.
Remove the gap in the LUN
numbering by editing the host's
LUN mapping (see
LUN
mapping),
or if a virtual device(s) has been
destroyed on the VLS, creating a
gap in the LUN numbering, restart
the VLS device emulations. The
VLS software will reassign LUNs
to the virtual devices as necessary
to remove any gaps in the LUN
numbering. See
Restarting the VLS
device
emulations.
HP StorageWorks
and
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