As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
As information handling systems become more complex due to increasing operating demands, it is important for such systems to allow for user flexibility while maintaining high levels of operation and performance. One option manufacturers offer to satisfy consumer needs are information handling systems that include one or more configurable components. The configurable components allow consumers to use the system in one or more different modes of operation. The configurable components allow consumers to change the operation of their systems without having to buy a new system. Consumers desire the configurable components because it provides greater flexibility in performing tasks with the information handling system.
One example of a configurable component is a backplane or motherboard such as a Small Computer System Interface (SCSI) backplane. A reconfigurable backplane can be used by the consumer in a split mode or a non-split mode. In the non-split mode, the backplane has a single SCSI bus route. One controller, such as a Redundant Array of Independent Disks (RAID) controller, manages all of the hard disk drives interfaced with the backplane. However, some consumers may prefer a split backplane in order to optimize all the resources of the information handling system. Many management functions require a particular number of drives. For example, RAID 5 requires three hard disk drives. Therefore if a function uses only three of the eight hard disk drives interfaced with the backplane, it would be useful to utilize the other five drives. Therefore, a user may prefer to configure the backplane in a split mode including two SCSI bus routes and two RAID controllers managing the hard disk drives. Having two controllers allows for the drives associated with the backplane to be used for different functions. Therefore, a configurable backplane allows for flexible and efficient use of the information handling system.
Despite the flexibility of information handling systems having reconfigurable components such as a backplane, these systems typically suffer from problems due to the configurability. For instance, configurable backplanes experience problems with stubs and the placement of external connectors. Stubs are bus route dead ends and generally occur due to the placement of one or more passive terminations at the end of the bus route. The passive terminations do not allow for a single, uninterrupted bus route in different configurations of operation. Therefore, reconfigurable systems must be designed to have more than one bus route with the bus routes present in more than one modes of operation, but only intended for use in one mode of operation. Therefore, in one or more modes of operation the bus route serves no function and leads to an unnecessary bus route dead end or stub. The stubs typically have a detrimental effect on signal integrity by limiting the bus frequency and potentially resulting in corruption of data. When a signal encounters a stub, the signal travels along both the stub and the intended bus route. Because the signal travels along both routes, the signal strength decreases resulting in potential degenerate system performance. Furthermore, the stub generally causes reflections in the signal because the signal bounces back after hitting the dead end of the stub. This reflection may further add to the data corruption. And as information handling system operations increase in speed, these reflections magnify causing further data corruption.
Information handling systems including reconfigurable components such as configurable backplanes also experience problems with the placement of the components on the backplane. For instance, a configurable backplane having two modes of operation requires two connectors for two controllers to access the backplane when operating in a split mode. The two connectors are typically not located together on the backplane and are generally not located on an edge of the backplane for easy accessibility. It is difficult to move the passive terminations thereby requiring the second bus route to enter the backplane from a new route located on a side different than the first bus route. Having the connectors on two different sides of the backplane creates problems with manufacturability and serviceability.