HP-UX 11.11
EMC powermt for PowerPath (c) Version 3.0.3
Fail over mode=1 at Clariion

As you can see only single HBA/Basisfailover
eurdbs3d:/root# powermt display dev=c33t3d4
CLARiiON ID=xxxxxxxxxxxxxx
Logical device ID=60060160F1731100799E3EEE2543DB11
state=alive; policy=BasicFailover; priority=0; queued-IOs=0
Owner: default=SP A, current=SP A
==============================================================================
---------------- Host --------------- - Stor - -- I/O Path - -- Stats ---
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
33 0/0/12/1/0.97.4.19.0.3.4 c33t3d4 SP A0 active alive 0 1
34 0/0/12/1/0.97.6.19.0.3.4 c34t3d4 SP B0 active alive 0 1

IO timeout set to 180 as usaul. Both paths are in VG.
eurdbs3d:/dev/rdsk# pvdisplay /dev/dsk/c34t3d4
Device file path "/dev/dsk/c34t3d4" is an alternate path
to the Physical Volume. Using Primary Link "/dev/dsk/c33t3d4".
--- Physical volumes ---
PV Name /dev/dsk/c33t3d4
PV Name /dev/dsk/c34t3d4 Alternate Link
VG Name /dev/vg42
PV Status available
Allocatable yes
VGDA 2
Cur LV 1
PE Size (Mbytes) 32
Total PE 2156
Free PE 262
Allocated PE 1894
Stale PE 0
IO Timeout (Seconds) 180
Autoswitch On
Proactive Polling On

Here is the error .As per the logs LUN is NOT switching(may be switching but not able to use the other path) between SPs rather loosing the connection to both SPs at the same time

Dec 1 14:04:21 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x213400 Failed! The PV is not accessible.
Dec 1 14:04:21 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x223400 Failed! The PV is not accessible.
Dec 1 14:04:26 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x213400 Recovered.
Dec 1 14:04:26 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x223400 Recovered.
Dec 1 14:06:29 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x213400 Failed! The PV is not accessible.
Dec 1 14:06:29 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x223400 Failed! The PV is not accessible.
Dec 1 14:06:34 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x213400 Recovered.
Dec 1 14:06:34 eurdbs3d vmunix: LVM: VG 64 0x2a0000: PVLink 31 0x223400 Recovered.

I have another LUN coming from same array/HBA/VG which is not reporting any error. Is there any LUN level property/settings which related to failover/pathswitcing?

As you can see there is license for Clarrion (single HBA)
eurdbs3d:/root# emcpreg -list

Key BJIY-D2YM-VKCU-F2HA-TW9H-IN6M
Product: PowerPath
Capabilities: Symmetrix

what is your thoughts?