HP-UX OS Version -11.31 Integrity superdome and Itanium CPU.
Cluster version: Service Guard version 11.19
I have further checked and found that this problem is caused by a missing patch PHSS_40145 on HP-UX 11.31 server which I scanned. During the port scanning phase, Nessus/(any port scan can cause) initiated the reboot of the server.
PHSS_40145: 11.31 Serviceguard A.11.19.00
ABORT PANIC If cmcld receives unexpected data cmcld may hang
resulting in a node TOC. The following messages will be logged in flight
log SEC:01: Event - Unknown message version
Fix is available via below patches
PHSS_40144 Serviceguard A.11.19 on HP-UX 11.23
PHSS_40145 Serviceguard A.11.19 on HP-UX 11.31
So it is recommended to apply these patches before doing any scans and Please ensure the scans are conducted during the non-bussiness hours.