If you upgrade (to a new code family i.e. 08.0.80 form an 08.0.30 build), make sure EVERYTHING works before you do so before your first "write mem" after booting the new code. The reasoning is that on a switch like yours running 08.0.30h, when you upgrade it to say 08.0.80d it will pre-parse the configuration on boot interpolating it over into an 08.0.80 configuration. Specifically, it reads the startup-configuration and writes a new running-configuration where normally a device that boots merely copies the startup-configuration into the running-configuration.
If you do a "write mem" you now have an 08.0.80 configureation in the startup-configuration. Things change like the way Access-Lists were made, how LAGs (Cisco calls them Ethercahnnel or Port-Channel) are configured, Native-Vlans have changed to no longer used the "dual-mode" keyword, and inline power is on by default for PoE devices without any power argumetns on the interfacdes. If you were to rollback to an 08.0.30 firmware, it would NOT be able to read the entire 08.0.80 configuration breaking LACP, Access Lists, Native VLANS, not powering PoE devices etc.