Browse Prior Art Database

Address switch with conflict indicator

IP.com Disclosure Number: IPCOM000014572D
Original Publication Date: 2000-Oct-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Abstract

Many computer peripheral interconnections use a simple addressing scheme to differentiate between different devices. A typical small computer system might have up to 16 SCSI storage devices on the same bus. Larger computer systems could have up to 128 fibre channel arbitrated loops (FC-AL) storage devices. Each storage device must have a different address if the bus is to operate correctly. The address settings of SCSI storage devices, and groups of FC-AL storage devices, are usually controlled by rotary switches.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Address switch with conflict indicator

Many computer peripheral interconnections use a simple addressing scheme to differentiate between different devices. A typical small computer system might have up to 16 SCSI storage devices on the same bus. Larger computer systems could have up to 128 fibre channel arbitrated loops (FC-AL) storage devices. Each storage device must have a different address if the bus is to operate correctly. The address settings of SCSI storage devices, and groups of FC-AL storage devices, are usually controlled by rotary switches.

     FC-AL products have a 7-bit address setting for the storage devices. In a typical system there will be up to 16 storage devices in each enclosure. The enclosure address switch sets the most significant 3 bits of the address. The least significant 4 bits of the address are used to differentiate between the 16 storage devices within the enclosure. If two enclosures within the same FC-AL loop have the same address switch setting, there will be a bus conflict. The FC-AL addressing scheme is quite sophisticated, so in this case the host computer will instruct all the devices to talk on the bus using a method called "soft addressing". However the preferred method is to have all devices at unique addresses so that all operations are done using "hard addressing".

     Our recent experience with installation of FC-AL products is that users can find this difficult and misleading. People who are experienced with using FC-AL storage devices still make the mistake of connecting two enclosures together with their address-switches set to the same value. This leads to complications when they try to configure their system.

     The novel method is to add an indicator close to the address switch. When the enclo...