Process mcmgr is the multicast manager which takes care of storing the multicast entries. Looks like this process got crashed which led to switch reboot.
I would recommend you to open a case with GTAC to further investigate the crash.
While opening a case, I would recommend you to include following details to the case:
1. Was there any configuration change made to the network or switch prior to the crash? 2. Provide the complete show tech all output 3. We would also need the core dump which is available in ls internal-memory which can be taken out using the "upload debug <tftp IP>" command.