You do understand that the cost of a high-availability cluster is extremely high. For every 9 you add, you increase the cost 10x. So, if it costs $10,000/year to provide 99% uptime, it will cost $100,000/year to provide 99.9% uptime. And, so on.

Those values don't mean very much, so let's use some useful numbers. There are 86,400 seconds in a day. Assuming exactly 365 days in a year, you have 31_536_000 seconds in a year. 99% uptime means you are allowed to be down for 315_360 seconds. That's 3.65 days, or 1h 41m every week. (If your maintenance window is 2 hours every Sunday night, you just blew 99% uptime.) 99.9% uptime is .365 days, or roughly 8h 45m, downtime. 5-9's, or 99.999%, uptime, means that you're allowed to be unavailable for 315.6 seconds, or 5m 15.6s, in a year. That's maintenance, backup, and everything.

I hope your company plans on making a lot of money with this site cause your administration costs for high-availability are going to be a bitch.

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In reply to Re^3: LAMP svrs - 1 or 2 is best ? by dragonchild
in thread LAMP svrs - 1 or 2 is best ? by j_c

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