Re: SONET ring questions

["Roeland M.J. Meyer" <rmeyer () mhsc com>]

At 10:34 PM 10/16/98 -0700, Alan Hannan wrote:
> > For total system uptime
> > 90.0% (one nine or less) Desktop systems.
> > 99.0% (two nines) Intermediate business systems
> > 99.9% (three nines) Most business data systems and workgroup servers
> > 99.99% (four nines) High-end business systems and your friendly
> > neighborhood telco
> > 99.999% (five nines) Bank Data Centers and Telco Data Centers, some ISPs
> > 99.9999% (six nines) Only God and Norad live here.
> > 99.99999% (seven nines) Even God doesn't have pockets this deep.
>
>  What's your source for this data?

You mean, besides 22 years in the system design and development trade?
Well, you can start with the various companies I have worked for. Then the
manufacturing specs on the various systems. My last analysis involved
two-headed server setup on HP 9000 series T520 with MC service guard and
shared RAID5. HP guarantees that at three nines. With the right add-ons I
got it to four nines (Complete second site in AZ, 1500 miles away). Very
expensive. Five nines would have broken the budget, that was Wells Fargo.

Northrup/Grumman MD-18 flight-line support.

The PacBell broadband system was quad redundant data centers in Fairfield
and San Diego. I was hired in as the Techinical Architect for that system.
Again, HP equipment. That system would have hit five nines, or better, in
production. I think we were pushing past $16M on that system, thirty-six
specially configured T520's plus RAID packs.

Various systems I worked on in Patrice Carrol's org in MCI COS (Garden of
the Gods facility), including the Fraud Management System.

This stuff is more art than science, too many non-deterministic variables.
Experience is the only thing that counts. It tells you which formulaii to
use and when they have a chance of working.

I should have my web-site up again this week-end, we're converting to
FastTrack with LiveWire, in addition to Apache-SSL/mod_perl.

___________________________________________________ 
Roeland M.J. Meyer, ISOC (InterNIC RM993) 
e-mail: <mailto:rmeyer () mhsc com>rmeyer () mhsc com
Internet phone: hawk.mhsc.com
Personal web pages: <http://www.mhsc.com/~rmeyer>www.mhsc.com/~rmeyer
Company web-site: <http://www.mhsc.com/>www.mhsc.com/
___________________________________________ 
I bet the human brain is a kludge.
                -- Marvin Minsky