eBay - STAYING ONLINE - ALWAYS

continued from : TECHNOLOGY

Another Starfire server was used to support eBay's quality assurance operations and two for the company's test environment. Enterprise 6500 and Enterprise 4500 servers powered the search engines. Additionally, StorEdge disk arrays housed over 2.7 terabytes of data. Numerous workstations also supported various functions including software development and system administration. The enterprise servers provided an ideal platform to eBay for numerous applications including enterprise resource planning, electronic commerce, data warehousing, Internet/Intranet and customer management systems. With the clustered server architecture, eBay significantly improved its site availability. The company had also reduced the average downtime of failover to another machine, which was previously between two to four hours to between 10 minutes and one hour.

eBay's third backup system was not of much help as a database problem brought down the site again after 40 minutes.Industry experts felt that though the clustered server approach was easier to administer, it was also more prone to breakdowns as the servers shared central resources, like the operating and storage systems. They argued that other high-traffic sites used more loosely integrated server farms^[1], in which many small, low-end servers perform identical functions in a redundant configuration. The search engine Google, for instance, used 4,000 Linux servers that searched and served web pages in parallel, while Yahoo used clusters of Unix servers. If one server went down, the rest picked up the load.

To tackle the problems in its storage system, eBay partnered with Sun to develop a storage solution, with high availability, resilience, and serviceability known as Storage Area Network (SAN)^[2] . Webb explained the benefits, "We have been moving and segmenting our entire database server into smaller servers. This helps ensure we don't have any single point of failure. In other words, an outage will affect just a portion of the system not the whole site. It will also be more cost-effective because the SAN will enable us to have six or more front-end machines to every two-recovery machines, instead of a one-to-one cluster. A SAN will also allow us to scale the system without accruing any downtime."

In September 2001, eBay went on a major software revamp to improve its site availability and make it more dynamic and interconnected. After reviewing more than 20 vendors, the company finally opted for IBM and its WebSphere application server and began to put in place its 'V3' application architecture. eBay also revamped its server-side application development architecture to support the Java 2 Enterprise Edition (J2EE)^[3] and Enterprise JavaBeans^[4] The company replaced a C++^[5] object framework that required a lot of structural programming. Though the C++ environment was more flexible than Cobol, it couldn't compete with J2EE, which was becoming the de facto application development framework. J2EE's objects could handle a much higher level of abstraction than C++. The new applications were more widely distributed, running across multiple machines (both Windows and Solaris) and relied on data-dependent routing, which utilized server cache^[6] more efficiently.

The V3 deployment was phased in slowly. It began during the fourth quarter of 2001 and was to be completed over the next 18 months. By December 2001, eBay's IT infrastructure had not only become flexible enough to handle instant recoding but also sturdy enough to process more than 800,000 transactions every minute.

REAPING THE BENEFITS

[1] A server farm is a group of networked servers that are located in one area. It streamlines the internal processes by distributing the workload between the individual components of the farm and expedites computing processes because of multiple servers.

[2] Storage Area Network (SAN) is a high-speed sub network of shared storage devices, which contain disks for storing data. It makes all storage devices available to all servers on a LAN or WAN.

[3]J2EE was the de facto industry standard for developing Java applications. It includes technologies for deploying web services that enable applications to work in conjunction on the web.

[4]ava beans are portable, reusable Java software components. EJBs extend the Java bean concept from the client domain to the server domain. EJBs enable the usage of Java technology into a robust, scalable environment that can support mission-critical enterprise information systems.

[5]C++ is the programming language for graphical applications, running on Windows and Macintosh environments.

[6]A special high-speed storage mechanism which can be either a reserved section of main memory or an independent high-speed storage device. Two types of caching are commonly used in personal computers: memory caching and disk caching.

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