<snip> > The criteria are quite different. A public phone system that connects > 0.0001 percent of calls to the wrong place and drops a similar number > in mid call is perfectly acceptable. A phone system (even a single > local switch serving 10,000 lines) that is down for one minute a week > is completely unacceptable. > > A telephone billing system that computes the wrong price for 0.0001 > percent of billed calls is completely unacceptable. But if the billing > system is down one minute per week, no one will even notice. > > Google search is a lot more like the phone system than it is like the > phone billing system. > > Tony H. > <unsnip>
Google is designed to be reliable at the system level running on unreliable hardware. See: http://www.networkworld.com/news/2006/062906-google-builds-own-servers-for.html?t51hb&nladname=wirelessal The telephone billing systems for the 'baby bells' IIRC is z/OS based. Billing inaccuracies has little to do with platform stability and everything to do with application design. Do to the complexity of the billing systems, far more than 0.0001 percent of the billings are incorrect to some degree. There is an entire industry (example: http://www.ameritelinc.com/phone-bill-analysis) whose sole purpose is to find inaccuracies and recoup costs. My main point is that application design and implementation can overcome the inherent unreliabilities of hardware and other software components. zSeries hardware proves the point. It has redundant internal components and instruction retry which are engaged transparently to the application and (I think) to the operating system. IBM has invested billions to make this work correctly. z/OS has many dynamic recovery features (sysplex, etc.) built in that allow applications platforms (CICS, IMS, DB2, etc.) to survive failures. > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
