Cendant, the travel services company that owns the Galileo reservation system for booking airline tickets and hotel accommodations, has just unplugged a bunch of big Unix SMP servers and replaced them with x86 servers running Linux. The move is part of a long-term strategy to get as many applications off IBM mainframes and big Unix boxes as makes sense.
Because of the complexity of managing passengers, routes, fares, and airplanes in real-time, airline travel reservation systems were among the early and enthusiastic adopters of mainframe technologies. The airlines even have their own mainframe operating system, called Transaction Processing Facility, which predates relational databases by decades. The Sabre system, developed by American Airlines, and the Galileo system, developed by Aer Lingus, Air Canada, Alitalia, Austrian Airlines, British Airways, KLM Royal Dutch Airlines, Olympic Airways, Swissair, TAP Air Portugal, United Airlines, and US Airways, are the two big reservation systems, and they still use TPF running on mainframes. But a lot of the applications that hook into these mainframes or that rely on information stored in these mainframes are not running on TPF. Many new applications created in the 1990s, such as self-serve, Web-based ticket booking, were developed to run on then-cheaper Unix boxes. But those Unix boxes are pretty expensive compared to Linux running on Intel iron, and that is why, says Bryan Harwood, director of platform architecture at Cendant’s Travel Distribution Services unit (which owns Galileo and a slew of other units such as CheapTickets.com and eFares), companies like Cendant are moving some applications off Unix and onto Linux.
The CheapTickets site still runs on Unix servers, which support the Apache Web server and Tomcat application server. These machines present a Web front end to the Galileo system for flight and hotel reservations, which is still on mainframes running TPF and probably will be for a very long time. (Hardwood won’t say whose Unix servers Cendant uses, except that they are not ones with RS/6000 or pSeries labels on them; we are 99 percent sure the company’s dominant Unix server supplier is Sun Microsystems Inc.) Calculating the fare for airline tickets is a separate part of the transaction, because the prices of fares are constantly changing and based in large measure on competitive pressures and the availability of seats. The modern fare systems have to be able to hunt for the cheapest fares and the shortest routes, and it is here that the Galileo 360 eFare application takes over. This is the application that has been ported from Unix SMP servers to a cluster of Lintel boxes made by IBM running Red Hat Enterprise Linux 3.
Specifically, the eFares application has been ported to 100 xSeries 440 and xSeries 445 servers in four-way and eight-way configurations. These servers are running the North American fares system and by the end of the year will be running the remaining international fares currently still being processed by the Unix boxes. The eFares system reads fare information from over 500 airlines into memory and feeds that information at a rate of 300 to 400 transactions per second to travel and airline agents around the world. Hardwood says that the current Linux cluster has about three times the throughput of the Unix setup, and that over the course of three year’s time the Lintel boxes will cut the cost of processing fares by 90%. Right now, the applications are running in 32-bit mode, and Cendant is evaluating what would happen to performance and scalability if it started using 64-bit Xeon or Opteron processors instead of the 32-bit Xeons at the heart of the current Lintel cluster.
Cendant also has another business called Neat.com, which provides information and bookings for packaged vacations. This application runs on six IBM BladeCenter machines with a total of 140 Xeon processors, which run Red Hat’s older Enterprise Linux AS 2.1 operating system.
