Assuming IPMI has been configured, it's possible to get Illumos systems to generate a sytem crash dump by sending the host a NMI (non-maskable interrupt) via IPMI. To send an NMI first obtain ipmitool from its website. Then issue the following command:
Once receiving the NMI, the crash dump will be written to /var/crash and the system will reboot. Please contact Joyent support (if you are a customer) or engineering via the Freenode IRC channel #smartos or the smartos-discuss mailing list, as they'll likely be interested in taking a look at the dump.