Database Corruption because of Power Failure?

[Judd]

Sorry to bother you all,
    I am looking to implement a cyrus-imap server that at any point in
time can have a good number of 15,000+ users reading and writing. If
it experiences a power failure and reboots, could the database become
corrupted and require restoration from backups?
    If no, what, if any data will be lost?
    In the event of a failure, and I am required to restore my data from a
backup, how long does it take to reconstruct a cyrus database for a
system of messages on the order of 500 Gigabytes in total. I
understand that this data is particular to the box that Cyrus IMAP is
running on but if anyone has the time it took them to reconstruct the
database that would be awesome.

Thank you so much for any help you can give,

Judd