Troubleshooting help needed: Server goes unresponsive.

I inherited this system a year and a half ago. I have learned a ton since then, but still I feel like a novice. I have a 2 in 1 custom built unit that has openindiana/napp-it on one side and esxi with windows server and active directory on the other. I have four setups like this and three of them seem to work without much difficulty. But one is giving me fits and goes unresponsive randomly. I am unable to access it through ssh and webgui. All SMB and NFS stores don't show up and the unit requires a reboot to get everything back up and running.
Where do I look first to start the troubleshooting process?

 

I would first check for a bad disk, cabling or backplane problem.

- napp-it menu system > log or system > fault or menu pool (soft, hard, transfer errors)
- napp-it menu disks > smartinfo > short smart check of disks

 

Here is the log from today (it failed today)

Sep 16 14:09:46.4538 ireport.os.sunos.panic.savecore_failure
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_static_start
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_static_end
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_send_targets_start
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_send_targets_end
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_slp_start
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_slp_end
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_isns_start
Sep 16 17:14:16.3748 resource.sysevent.EC_iSCSI.ESC_isns_end​

There are a couple more from the past month

Aug 26 09:00:12.1351 ireport.os.sunos.panic.savecore_failure
Sep 01 09:49:15.1476 ireport.os.sunos.panic.savecore_failure​

 

I did the smart check on the disks and it looks like one of them did come back as bad. Thanks for your help!

 

That's great.