FYI-- "5 Nines" efficiency

[jrm2incv]

Guys,

I enjoyed the Linux HA / DRDB discussions & demo last night (Tues.,
20-May) -- THANKS to John Hyde for your excellent presentation.

Anyway, the one thing I couldn't let go of last night was the concept
of what 99.999 represents. I recalled from a Jeremy Cioara CCVP
lecture (CVOICE CBT Nuggets ) that "Five Nines" meant about 5 minutes
of downtime per year. But I could not recall exactly where Cioara said
this while at the meeting last night. However, I found the following
under "uptime" on wikipedia.org...

"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
(similar to the unit of metallic purity). "Five nines" means 99.999%
availability, which translates to a total downtime of approximately
five minutes and fifteen seconds per year."

Anyway, many thanks again to John Hyde and Gil Lamb for setting up
last night. Very cool.

Jose Minas