A Troub lesh ooting
This appendix describes some com mon issues you may encounter while configuring the VLS.
Common issues
Symptom
Possible causes Solution
Increase the maximum number of
LUNs per device the op erating
system is configured to see. To
change the maximum LUN per
device setting:
• Microsoft Windows—See
h
ttp://s upport.microsoft.com/
default.aspx?scid=kb%3ben-
us%3b310 072.
• HP-UX—The value cannot be
changed.
• O ther operating systems—See
the op erating system web site.
There are more LUNs on the FC
host ports than the operating system
is configured to see. Once the
maximumnumberofLUNsona
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 ma ximum number of LUNs an
operatingsystemisconfigured to
seeiseight,theoperatingsystem
will only see LUN0, LUN1, ..., LUN7
and will not see LUN8, LUN9, ...,
anduponeachFChostport. By
default Windows and HP-UX hosts
can see a maximum of 8 LUNs per
FC host port.
Use the VLS’s LUN masking feature
to restr
ict the number of virtual
devices
the host sees on the VLS
FC host p
ort(s), so it only sees the
virtua
l devices it needs to see. Then,
use the
VLS’s LUN mapping feature
to assi
gn LUNs to the virtual devices
the ho
st can see, such that the
virtu
al device LUN numbers include
aLUN0
and no gaps in the LUN
numb
ering. See LUN masking and
LUN mapping for instructions.
Some of the virtual
devices are not detected
by the operating system
when it scans the S AN
for new hardware.
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 findaLUN2,itwillassume
there are no more LUNs on the port
andstoplooking.
Remove the gap in the LUN
numbering by editing the host’s
LUN mapping (see L UN 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 V LS
device emulations.
HP StorageWorks
147
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