Put it like this, 99.999999% of the time a firmware update will not effect the data. However in very rare occasions it does. Make sure you have the Terastation contected directly to the PC with static IP addess set and all AV and firewall software disbaled. Then run the update. Ideally you should have your data backed up to another device. Even though the TS is RAID5 you should never relie on one piece of HW to store all your data on.