system locked up

I had a weird issue with OMV last night so I thought I'd post about it. Normally my system has been stable and reliable with no issues whatsoever. However last night it froze up while running a snapraid sync. I opened another terminal and killed the snapraid process. Tried running a sync again and this time it froze at 0%. Issued a reboot command and the machine went down but didn't come back. At this point I powered the machine down and then powered it up and it booted. I have been able to run a snapraid sync and scrub without any further complications (everything seems normal). Any thoughts on where to look to try to figure out what the problem was? System uptime was in the neighborhood of 45 days prior to this issue last night.