[ILUG] Linux uptime statistics

[Rick Moen]

Quoting Niall O Broin (niall at linux.ie):

> You should certainly stick to Linux, rather than statistics. With your
> arithmetic, 90 sec. downtime per quarter only gets you three nines,
> whereas it's really four, and damn near five. 

<shrug>  My point is unchanged:  Past a couple of months, going for
prolonged uptimes becomes, at first, a little silly, and eventually
actively harmful:  Eventually, you need to replace your kernel and
reboot to eliminate known DoS weaknesses or various exploit
vulnerabilities that emerge on rare occasions.

Just because it's theoretically possible to keep an *ix box running
without reboot for arbitrary numbers of years (especially if given
backup mains power and a safe, isolated network environment), that
doesn't mean the sysadmin will (or should) want to.

By the way, I'm having a difficult time figuring out what you're saying
was wrong with my earlier calculation.  I've just re-done the _arithmetic_
carefully; if you're saying there's something wrong with the conceptual
framework (as you say, the "statistics"), then please do explain.  Thanks.

Number of seconds in a quarter:  60 x 60 x 24 x 90 = 7,776,000
Percent uptime over a quarter, given 90 seconds of downtime during 
    that quarter:  100 * ( 1 - 90 / 7,776,000 ) = 99.998843 %

-- 
Cheers,            "Please return all dogmas to their orthodox positions."
Rick Moen                                 -- Brad Johnson, in r.a.sf.w.r-j
rick at linuxmafia.com