Paul Rubin wrote:
Tim Daneliuk <[EMAIL PROTECTED]> writes:
I worked for an Airline computer reservation system (CRS) for almost a decade. There is nothing about today's laptops that remotely comes close to the power of those CRS systems, even the old ones. CRS systems are optimized for extremely high performance I/O and use an operating system (TPF) specifically designed for high-performance transaction processing.
Yeah, I've been interested for a while in learning a little bit about how TPF worked. Does Gray's book that you mention say much about it?
I honestly do not recall. TPF/PAARS is an odd critter unto itself that may not be covered by much of anything other than IBM docs.
I think that the raw hardware of today's laptops dwarfs the old big
iron. An S/360 channel controller may have basically been a mainframe
in its own right, but even a mainframe in those days was just a few
MIPS. The i/o systems and memory are lots faster too, though not by
nearly the ratio by which storage capacity and cpu speed have
increased. E.g., a laptop disk these days has around 10 msec latency
and 20 MB/sec native transfer speed, vs 50+ msec and a few MB/sec for
a 3330-level drive (does that sound about right?.
Again, I don't know. The stuff we had was much newer (and faster) than that.
Web servers are very sessions oriented: make a connection-pass the unit of work-drop the connection. This is inherently slow (and not how high performance TP is done). Moreover, really high perfomance requires a very fine level of I/O tuning on the server - at the CRS I worked for, they performance people actually only populated part of the hard drives to minimize head seeks.
Today I think most seeks can be eliminated by just using ram or SSD (solid state disks) instead of rotating disks. But yeah, you wouldn't do that on a laptop.
But that still does not solve the latency problem of session establishment/ teardown over network fabric which is the Achilles Heel of the web and web services.
For a good overview of TP design, see Jim Gray's book, "Transaction Processing: Concepts and Techniques".
Thanks, I'll look for this book. Gray of course is one of the all-time database gurus and that book is probably something every serious nerd should read. I've probably been a bad boy just for having not gotten around to it years ago.
P.S. AFAIK the first CRS systems of any note came into being in the 1970s not the 1960s, but I may be incorrect in the matter.
From <http://en.wikipedia.org/wiki/Sabre_%28computer_system%29>:
The system [SABRE] was created by American Airlines and IBM in the 1950s, after AA president C. R. Smith sat next to an IBM sales representative on a transcontinental flight in 1953. Sabre's first mainframe in Briarcliff Manor, New York went online in 1960. By 1964, Sabre was the largest private data processing system in the world. Its mainframe was moved to an underground location in Tulsa, Oklahoma in 1972.
Originally used only by American, the system was expanded to travel agents in 1976. It is currently used by a number of companies, including Eurostar, SNCF, and US Airways. The Travelocity website is owned by Sabre and serves as a consumer interface to the system.
I stand (sit) corrected ;) -- ---------------------------------------------------------------------------- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
