Description of the Related Art Distributed computing systems (or computer networks) are generally known. Computer networks typically comprise a plurality of personal computers, or workstations, or network appliances and other data processing devices connected together for information exchange. At the heart of the computer network is one or more network servers, hereafter generally referred to as"servers."In most computer networks, network servers are responsible for managing the network, running applications, and administering documents or data generated at the attached data processing devices.

Network servers typically include one or more AC or DC power supplies, which serve the purpose of keeping the system up and running. Externally generated power which is provided to the server may have unacceptably wide variations in voltage and/or current. As a result, network servers typically filter power before supplying the power to sensitive components in the server.

Due to the fact that network servers manage and/or store data generated, the network server typically has mass storage capabilities. The mass storage capabilities may be implemented by a disk subsystem or disk array where one or more disk drives are combined. SCSI is one example of an interface standard that permits multiple hard disk drives to be daisy chained to a single interface connector.

One or more network servers are typically found in the data center for Internet Service Providers (ISPs) and Application Service Providers (ASPs). One issue at sites supporting network servers is that space is often at a premium, and the servers are often rack mounted and closely co-located. An additional issue is found in the need for network servers to be scalable, given the disparate size and growth rates of ISPs and ASPs.

As mentioned previously, sites supporting rack mounted network servers often have limited space. The servers should be designed with care to permit easy access and maintenance despite the limited space. To complicate matters, data centers in different geographical areas have different operational requirements. For example, American telecommunications service providers generally follow the spacial and environmental requirements defined by Network Equipment Building Standards (NEBS). In contrast, European telecommunications service providers generally follow standards defined by the European Telecommunications Standards Institute (ETSI). One difference between American and European telco requirements is the power cabling of servers. American telco servers traditionally receive power from the rear of the server, and European telco servers traditionally receive power from the front of the server. In addition, beyond the typical requirements in America and Europe, a particular service provider's needs might be unique, or change over time.

One possible solution is to manufacture a standard configuration having either rear access power or front access power. In the event that a telco provider's requirements differ from the standard configuration, a power

cable external to the chassis can run from the side of the server with a power inlet to the side of the server with access to external power. This approach has multiple disadvantages. An extra cable outside of the chassis adds yet another point of failure to the server, potentially decreasing the amount of uptime server availability. In the event that the cable fails, replacing the cable could be quite difficult if the server's power inlet is positioned on an inaccessible side of a server, requiring the entire server to be physically moved-just to replace the cable.

Therefore, what is needed is a solution selectably permitting front or rear access power needs (or both) for a server. The solution could be flexible, and not force a user into an irreversible choice between front or rear access.

SUMMARY To overcome the limitations described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses an apparatus for selectively supplying unfiltered power through one or more of multiple unfiltered power inputs to a power filter supported in a computer chassis. Allowing for multiple power inputs-on the power filter itself and/or on one or more surfaces of the computer chassis-adds great flexibility in where power cables external to the computer chassis may be located.

Another embodiment is a power filter having multiple inputs for unfiltered power. The power filter also includes a power output for filtered power which has blind-mating capacity. The blind-mating capacity allows another component such as a backplane to easily be connected with the power filter.

Some method embodiments allow selectable routing of power through one of multiple surfaces on the computer chassis, adapting a power filter in a computer with multiple power elements. While the description is in terms of the best mode for achieving one or more objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of those teachings without deviating from the spirit or scope of the described embodiments.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows one embodiment of a computer system.

FIG. 2 shows another embodiment of a computer system.

FIG. 3 shows a further embodiment of a computer system.

FIG. 4 shows an embodiment of a power filter.

FIG. 5 shows a top view of a power filter.

FIG. 6 shows a cross sectional view of a power filter.

FIG. 7 shows a side view of a power filter.

FIG. 8 shows a side view of a housing cover.

FIG. 9 shows a perspective view of a housing cover.

FIG. 10 shows a power cable.

FIG. 11 is a flow diagram illustrating a method of selectably routing power through a computer chassis.

FIG. 12 illustrates a method for adapting a power filter.

FIG. 13 illustrates a method for selectively configuring a computer for receiving front access power.

DETAILED DESCRIPTION FIG. 1 shows one example of an embodiment of a computer system, or server. One example of the network server is the Netra ctl 600 by Sun Microsystems, Inc. This embodiment shows a computer system 100 including a chassis 110 supporting a processor 120 and a power filter 130. The processor 120 and/or the power filter 130 may be physically supported directly by the chassis 110, or indirectly, for example through a backplane.

Another example of a backplane may be a midplane. In a general, a power filter receives power generated externally from the server, and filters out unacceptable variations before supplying the power to the rest of the server. The power filter 130 includes a filter housing 140, a first power input 150, a second power input 160, and a power output 170. The power filter 140 receives unfiltered power from one or both of the first power input 150 and the second power input 160. After the power has been filtered by the power filter 130, filtered power enters the rest of the computer system 100 through a filtered power output 170. Various embodiments of the computer system 100 and the power filter 130 handle AC power and/or DC power.

FIG. 2 shows another example of a computer system embodiment. A computer system 200 further includes a backplane 280 supported by the chassis 110 and supporting the processor 120. The backplane 280 receives power from the power filter 130 through the power output 170. The power output 170 can include blind-mating technology, permitting the backplane 280 to blind-mate with the power output 170. The power filter 130 receives unfiltered power from the first power input 150 and a second power input 260. The, second power input 260 protrudes out of an aperture on a rear surface of the chassis 110. If not in use, the protruding second power input 260 may be covered to protect the computer system 200 and anyone servicing the computer system 200. An alternative embodiment does not have a protruding connector, but instead a cable coupling the second power input 260 to the rear surface of the chassis 110.

FIG. 3 shows a further example of a computer system embodiment. A computer system 300 further includes a power cable 310 coupling the first power input 150 to an aperture on a front surface of the chassis 110.

If the computer system 300 is not receiving power through the front surface of the chassis 110, the power cable 310 may not be included, and the first power input 150 may be covered to protect the computer system 300 and anyone servicing the computer system 300. The first power input 150 can be angled away from the rear surface of the chassis and/or toward the front surface of the chassis to ease a connection of the power cable 310 with the first power input 150. Alternatively, the power cable 310 can be included even if the computer system is receiving power through another power input and/or another surface, such as through a rear surface of the chassis 110 and the second power input 160. If a telco provider's requirements change, then power cabling external to the chassis can be rapidly modified, and the computer system can readily accept power through another surface of the chassis 110.

In another embodiment, the power filter 130 includes a single input, and the power filter 130 can selectably be coupled to receive power through the aperture on the front surface of the chassis 110 or through the aperture on the rear surface of the chassis 110.

In another embodiment, other surfaces of the chassis 110 define one or more apertures through which the computer receives unfiltered power, for example a side surface, a top surface, and/or a bottom surface.

FIG. 4 shows an exploded diagram of multiple parts of an embodiment of the power filter 130. The power filter 130 may handle AC and/or DC power. The filter housing 140 includes includes a housing cover 410. The housing cover 410 can be part of the filter housing 140 or a separate part. The first power input 150 may be positioned on any surface of the filter housing 140, and in this embodiment is shown positioned

on the housing cover 410. The filter housing 140 and the housing cover 410 support a filter 420. The filter 420 includes a first filter input 430 and a second filter input, not shown, on a rear surface of the filter 420. The positioning, shape, and configuration of the first filter input 430 and the second filter input is flexible. In another embodiment, the filter 420 includes a single input adapted to receive power through one or more of multiple inputs external to the filter 420. Filter outputs 440 and 445, output, for example, positive and negative 48 volts DC.

Another embodiment of the filter 420 may support AC voltage, for example anywhere from 90 V to 240 V.

Various other positioning, shape, number, and voltages for the filter outputs are possible. The filter outputs 440 and 445 are coupled to the power output 170. The power output 170 receives power from the filter outputs 440 and 445, and acts as a connector to another component within the chassis 110, such as the backplane 280. The power output 170 can include blind-mating features such as blindmating connector 460, for example to simplify coupling of the backplane 280 to the power output 170. The power output 170 may be accompanied by projections 458 and/or 462 that can help position the blind-mating connector 460 of the power output 170 relative to the filter housing 140.

The blind-mating connector 460 and the projections 458 and 462 of the power output 170 extend through apertures 452,454, and 456 defined by a plate 450. The plate 450 may be separate part or integral with the filter housing 140.

Other embodiments of the power filter position the power inputs and the power output such that the power inputs are positioned on the same surface, and/or the power output is positioned on the same surface as at least one of the power inputs.

FIG. 5 shows a top view of the power filter 130. In the top view, a second filter input 510 is visible. FIG.

6 show a cross-sectional view of the power filter 130, as viewed across a cross-section line 520 in FIG. 5. In the cross-sectional-view of FIG. 6, conductive protrusions 610 and an internal cable 620 are visible. The internal cable 620 connects outputs of the filter 420 to the blind-mating connector 460 of the power output 170. FIG. 7 shows a side view of the power filter 130.

FIG. 8 shows a side view of the housing cover 410 showing a side view of the conductive protrusion 610 and the first power input 150. FIG. 9 shows a perspective view of the housing cover 410 and the conductive protrusion 610 positioned on each side of the housing cover 410. The positioning, shape, and number of the conductive protrusions 610 may be adjusted in other embodiments.

FIG. 10 shows an exemplary power cable 310. The power cable 310 helps route unfiltered power from an aperture on the chassis 110 to the power filter 130. The power cable 310 includes a first end 1010, a main cable 1030, and a second end 1050. The main cable 1030 has a plurality of power conductors. These power conductors have a first end 1020 and a second end 1040. The first end 1010 of the power cable 310 includes conducting protrusions 1060 and 1070. When the first end 1010 of the power cable 310 is connected with the first power input 150 of the power filter 130, the conducting protrusions 1060 and 1070 of the power cable 310 come into conductive contact with the conductive protrusions 610 of the power filter 130, performing a grounding fucntion.

FIG. 11, FIG. 12, FIG. 13 show exemplary flow diagrams of some possible methods. Elements of the flow diagrams may be removed, rearranged, added to, and/or modified.

The flow diagram of FIG. 11 illustrates an exemplary method for selectably routing power through a front surface or a rear surface of a computer chassis. After start 1110, a decision is made whether unfiltered power should be routed through the front surface of the computer chassis or the rear surface of the computer chassis.

Unfiltered power refers to power which has not been filtered by a power filter within the computer chassis. In 1130, unfiltered power is routed through the rear surface of the chassis and then to the power filter within the

chassis. The power filter may handle AC and/or DC power. Alternatively, in 1140 power is routed through the front surface of the computer chassis and then to the power filter within the chassis. The method ends at 1150.

Other embodiments may route power through other surfaces, such as a top surface, a side surface, an/or a bottom surface.

FIG. 12 illustrates an exemplary method for adapting a power filter. After start 1210, in 1220 a first power input is connected to the power filter. In 1230, a second power input is connected to the power filter.

After 1240 where the power filter is positioned in the computer chassis, the method ends at 1250.

FIG. 13 illustrates an exemplary method for selectively configuring a computer for receiving front access power. After start 1310, in 1320 a power filter having a first input for unfiltered power and a second input for unfiltered power is positioned within a computer chassis. In 1330, a decision is made whether front access power is desired. In 1340, if front access power is desired, at least one of the unfiltered power inputs is coupled to the front surface of the chassis. The method ends at 1350.

While the preferred embodiments of the present invention have been illustrated herein in detail, it should be apparent that modifications and adaptations to those embodiments may occur to those skilled in the art without departing from the scope of the present invention as set forth in the following claims.