Interesting for all those people chasing "five nines": If 45 minutes today is their only downtime for the year, their annual uptime for 2013 will be just
"5 nines" works out to about 5 minutes of downtime a year: very challenging to achieve.
For reference, 4 nines is about an hour, and 6 nines is only ~30 seconds of downtime a year!
