15 | 09 | 2014
Uptime PDF Print E-mail
Written by R2Launch   
Uptime is a measure of the time a computer system has been "up" and running. It came into use to describe the opposite of downtime, times when a system was not operational. The uptime and reliability of computer and communications facilities is sometimes measured in nines. "Five nines" means 99.999% availability, which translates to a total downtime of approximately five minutes and fifteen seconds per year.
It is often used as a measure of computer operating system reliability and stability, in that this time represents the time a computer can be left unattended without crashing, or needing to be rebooted for administrative or maintenance purposes. Long uptime can also indicate negligence as many critical updates require reboot on some operating systems.

Table:
Total Downtime (HH:MM:SS) Availability per day per month per year
99.999% 00:00:00.4 00:00:26 00:05:15
99.99% 00:00:08 00:04:22 00:52:35
99.9% 00:01:26 00:43:49 08:45:56
99% 00:14:23 07:18:17 87:39:29