Browse Prior Art Database

Homogenous Control in Dual-Ported Serial Data Subsystems

IP.com Disclosure Number: IPCOM000035472D
Original Publication Date: 2005-Jan-20
Included in the Prior Art Database: 2005-Jan-20
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Abstract

In a network of dual-ported storage elements, managed by redundant Control Elements, a firmware method may be devised to provide indirection in the pin-mapping and allow the Control Elements to be identical and route through the shared planar in fewer layers and without rotation.

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TUC820040222 Jean Barkley/Tucson/IBM

Andrew E Seidel, Matthew D Bomhoff, Kenny N Qiu, Gregg Lucas, Brian Cagno

Homogenous Control in Dual-Ported Serial Data Subsystems

Dual-ported serial data elements, such as Fibre Channel disk drives, have independent dual-ports, allowing redundant access to the drive for increased reliability. A challenge is routing control and data lines from independent Control Elements to maintain truly separate control of each loop. For each Control Element to route to the same disk ports across a backplane, it would require a unique pin-out and use many routing layers.

As an alternative, firmware can be used to provide indirection and identical printed circuit boards may be used for both Control Elements. In this way, the pin-out of each Control Element is the same, yet will route to a different drive port, depending on which slot it resides. The firmware, aware of which slot by means of an identification-pin, remaps the pinout through use of individually-addressable General Purpose Input/Outputs (GPIO). As the routing is no longer unique, fewer layers are needed for the backplane and the boards need not be rotated to maintain symmetry.

To establish uniqueness, on the backplane, a master/slave pin in each slot is strapped in opposition to the same pin in the other slot and read by a processor on each Control Element. Firmware, running on the processor, uses t...