Let me say that I don't consider this a great achievement. Not having rebooted means you did not upgraded any kernel during this time, perhaps not did any upgrades at all ? I don't condider this wise. You have to plan some maintenance time to do these upgrades, to upgrade kernels and other PVE stuff and reboot the nodes. Doing this rather regularly will prevent also a long check of the ext3 file system. If you have for example a power failure, you will appreciate not having a long file system check...