If it again the  case try to force a crash dump on shutdown, e.g.
add /etc/system:

set pcplusmp:apic_panic_on_nmi = 1

then if the system is frozen
$ ipmitool -Ilanplus -U idrac-user -P password -H idrac-ip power diag

Note that you probably won't have any luck with a crash dump if the dump device is controlled by lmrc (if lmrc is the reason for frozen system)

long text:
https://illumos.org/docs/user-guide/debug-systems/#gathering-information-from-a-running-system-using-only-nmi-x86