...backup your data...or at least invest in a UPS.
I just wanted to share my story with you. This week there was a power outage in my building. Being unlucky me, it killed two of the hard drives in my sever which were in RAID 5. Not one, but two. The two drives wouldn't spin up anymore and made clicking noises. I lost around 5TB of data. On the bright side, I do have my pictures and music mirrored on an external hard drive, which are the most important files. Now $300 poorer, it's time to rebuild my library.