ThinkReservations was built with redundancy in mind. Your data is stored on our database, which has an up-to-the-moment backup copy that exists in a completely different data center.
We have systems in place to automatically "fail over" to the backup copy if the original database server has any issues. Every night, the entire data set (including your data!) is backed up and stored with 99.999999999% durability (eleven 9s of durability). Even the backups are stored across multiple data centers and time zones to make sure they are always available.
Suffice to say, your data is very safe!