The announcement told customers that the data loss was due to a “server failure”, though some have speculated that it was due to some sort of botched SAN maintenance. The story is truly sad since loads of people lost data including contacts, calendars, to-do lists, and photos; however it’s not nearly as sad until you factor in that the whole thing was easily preventable. In this case, Microsoft apparently didn’t have any sort of backups.

Interestingly enough, a lot of sysadmins seem to forget some basic rules of keeping valuable data around. After disasters like this, it’s important to examine our own operations with this cardinal rule in mind: replication is by no means of the imagination a backup. This is especially true when one tries to depend upon RAID to protect from data loss. RAID is effective against hard drive failures, but if you delete a file on one drive, it deletes it on the other. This is important to keep in mind as well when replicating data across a network either through a straight file copy or a clustered file system. No matter the method, keep in mind that you still need old copies for those accidental deletes.