HPUX : EXT_BUS LIMITATION ISSUE ON 11.23

it looks like we can see these disks/LUNs in ‘sar –d’ and ‘autopath display’ – yet 2 out of 4 paths can’t be seen in ‘xpinfo’ output and shows as NO_HW in ioscan.

We also seem to be having an issue with ext_bus limitation and the situation had been like this for at least couple of months now.

ext_bus 254  3/0/12/1/0/4/0.20.184.0.1    fcd_vbus CLAIMED     INTERFACE    FCP Array Interface

ext_bus 255  3/0/10/1/0/4/0.20.200.0.0    fcd_vbus CLAIMED     INTERFACE    FCP Array Interface

ext_bus 256  1/0/8/1/0/4/0.20.58.0.7               UNCLAIMED   UNKNOWN      FCP Array Interface

ext_bus 257  1/0/12/1/0/4/0.20.58.0.7              UNCLAIMED   UNKNOWN      FCP Array Interface

……

There are more than 255 ext_bus already. And might require a ioconfig reorg
Issue : as extn_bus has cross the limit of 255 limit, extn_bus number greater then 255 has been marked by kernal as no_hw, but IO request can be observe on device file in " sar -d 1 10 |grep -i <c?t?d? which is in no_hw status>

ext_bus     56  1/0/8/1/0/4/0.20.58.255.0         fcd_vbus  NO_HW       INTERFACE    FCP Device Interface

target      63  1/0/8/1/0/4/0.20.58.255.0.0       tgt       NO_HW       DEVICE

ctl         30  1/0/8/1/0/4/0.20.58.255.0.0.0     sctl      NO_HW       DEVICE       HP      OPEN-XP12000

ext_bus    146  1/0/8/1/0/4/0.20.86.0.0           fcd_vbus  NO_HW       INTERFACE    FCP Array Interface

ext_bus    147  1/0/8/1/0/4/0.20.86.255.0         fcd_vbus  NO_HW       INTERFACE    FCP Device Interface

target      36  1/0/8/1/0/4/0.20.86.255.0.0       tgt       NO_HW       DEVICE

ctl         64  1/0/8/1/0/4/0.20.86.255.0.0.0     sctl      NO_HW       DEVICE       HP      OPEN-XP12000

ext_bus    129  1/0/8/1/0/4/0.20.130.0.0          fcd_vbus  NO_HW       INTERFACE    FCP Array Interface

target      37  1/0/8/1/0/4/0.20.130.0.0.0        tgt       NO_HW       DEVICE

disk       1961  1/0/8/1/0/4/0.20.130.0.0.0.7      sdisk     NO_HW       DEVICE       HP      OPEN-V*3

ctl         33  1/0/12/1/0/4/0.20.218.255.0.0.0   sctl      NO_HW       DEVICE       HP      OPEN-XP12000

ext_bus     59  1/0/12/1/0/4/0.20.240.0.0         fcd_vbus  NO_HW       INTERFACE    FCP Array Interface

ext_bus     60  1/0/12/1/0/4/0.20.240.255.0       fcd_vbus  NO_HW       INTERFACE    FCP Device Interface

target     322  1/0/12/1/0/4/0.20.240.255.0.0     tgt       NO_HW       DEVICE

ctl         32  1/0/12/1/0/4/0.20.240.255.0.0.0   sctl      NO_HW       DEVICE       HP      OPEN-XP12000

ext_bus    259  3/0/12/1/0/4/0.20.251.255.0                 NO_HW       UNKNOWN      FCP Device Interface

Recommendation:
Need to look for possibility to release unsed extn_bus and reconfigure the ioconfig tree.

#Run the ioconfig_dump utility
/var/adm/crash/ioconfig/ioconfig_dump.exe

Create a new  ioconfig file called ioconfig.new.
## ioconfig_dump -w -o /tmp/ioconfig.new

Verify the instance mappings of the newly created ioconfig file
# ioconfig_dump -r  -o  /tmp/io.ascii.old

Total number of instances currently used:
# grep ext_bus /tmp/io.ascii.old|wc -l

#Backup /stand/ioconfig and /etc/ioconfig and copy ioconfig.new into both locations.
# cp /stand/ioconfig /stand/ioconfig.orig
# cp /etc/ioconfig /etc/ioconfig.orig
# cp /tmp/ioconfig.new /stand/ioconfig
# cp /tmp/ioconfig.new /etc/ioconfig

#shutdown -ry 0