RE: Measure database availability beyond 99.9%

From: Mark W. Farnham <>
Date: Fri, 29 Aug 2008 15:20:13 -0400
Message-ID: <>

Though rarely seen, the legitimate purpose could be the analysis of where to apply effort to increase the actual HA (measured as you suggest with service level monitoring). In brief, it is akin to Ahmdahl's law, but in availability you can't be available more than the availability of the least available component. Of course that is a ceiling since there is no guarantee of the coincidence of the other outages.

So if the database is significantly more available than network connectivity from clients, it does not make much sense to spend on increasing the availability of the database.



-----Original Message-----
From: [] On Behalf Of Niall Litchfield
Sent: Friday, August 29, 2008 3:04 PM
To:; Subject: Re: Measure database availability beyond 99.9%

Aaaarrrrgh! I'm sure there's a purpose that isn't lying to justify expensive investments. I just cannot see it. Real HA must do service level monitoring (aka can the users work) what you seem to propose has no clear benefit, please tell me I'm wrong.


Received on Fri Aug 29 2008 - 14:20:13 CDT

Original text of this message