SCSI, SCA-to-50, Wide to Narrow, how to terminate high byte - Page 1
Forum section: electronics / general

author: legacy
author_rank: Super Contributor
timestamp: June 27, 2015, 10:29:08 pm
content: SCA-to-50 adapterHD50 and HD68 to centronics C50 cablesHD box, for 2 HardDrivesSCSI connectorshi guysI have a pair ofSeagate ST136475LC SCSIhard drives, they are SCA/80pin, SE/Wide (16bit), and I have to connect them to a Wide Host through a Narrow cable (HD50--Centronics). It does not work at all, while connecting them to a Narrow Host is working good.Wide HD/Narrow cable/Narrow Host:not workingWide HD/Narrow cable/Wide Host:workingI am using the SCA-to-50 adapter you can see above.Two more points, it seems thatthe SCSI spec requires drives up to U160 to support narrow transfers, but U320 removes this requirement. So a compliant U320 drive may simply not support narrow operationSCA-50 adapters sometimes are just broken by designWhen I connect Wide HD/Narrow cable/Narrow Host, I get this error from the HOST controllerCode:completion status=0x1eSCS_AUTO_SENSE_FAILEDscsi status=0x2state flags=0x3f00status flags=0x85I am not able to understand it.btw, I'd like to see a schematic of a good Adapter SCA-to-50 which uses an high-byte terminator.

author: legacy
author_rank: Super Contributor
timestamp: June 27, 2015, 10:47:27 pm
content: Seagate ST136475LC SCSImanual

author: macboy
author_rank: Super Contributor
timestamp: June 29, 2015, 01:47:15 pm
content: You will need to force the controller into narrow (8 bit) operation. Otherwise the controller and drive will negotiate wide transfers between them (they both support it so why not?) but that will fail once they try to actually use the upper byte of the bus. If the controller has a BIOS (most bootable SCSI controllers on PC architecture do) then you should be able to do it in there, otherwise it will need to be through the driver or a setting or a config utility.Personally, I would pull those 50 pin connectors off the back of that box and run the 68 pin ribbon out the back and onto the 68 pin external connector of the computer. Or run it through a PCI slot into the box to the internal connector.

author: legacy
author_rank: Super Contributor
timestamp: June 29, 2015, 02:29:29 pm
content: sgi-scsi-board-with-hd50Quote from: macboy on June 29, 2015, 01:47:15 pmI have installed an HD50 (narrow) connector to the SCSI control board IHD50 (narrow). Unfortunately the board's firmware is not smart and sends a " Wide data transfer request" to the hard drive, it answers "yes, I can speak wide", so they try to talk 16bit each other through an 8 bit cableQuote from: macboy on June 29, 2015, 01:47:15 pmIt has not, it's for SGIQuote from: macboy on June 29, 2015, 01:47:15 pmFujitsu SCSI/SCA harddrives have a pretty jumper "force narrow", while the Seagate has notQuote from: macboy on June 29, 2015, 01:47:15 pmIrix, the Operating system, does not allow to config anything on that Qlogic boardQuote from: macboy on June 29, 2015, 01:47:15 pmThe machine does not allow to have other HDs internally, I have to use an external box, and I'd like to share this box with other Narrow machines.-> I have to buy Fujitsu, it seems, from the Seagate Barracuda's manual, that I do not have other choices

author: legacy
author_rank: Super Contributor
timestamp: June 29, 2015, 02:31:33 pm
content: also the manual saysQuotetoo bad

author: sync
author_rank: Frequent Contributor
timestamp: June 29, 2015, 03:12:15 pm
content: Use only 68 pin cables, connectors and a LVD terminator.Everything else is asking for trouble in your case. The Centronics connectors aren't suitable for high speed SCSI and maybe the Centronics cables are miswired and working only single ended. Also all the nice data corruption due incorrect SCSI wiring...Quote from: legacy on June 29, 2015, 02:29:29 pmNot even by editing some obscure kernel header files and relinking the kernel?(The IRIX way)

author: legacy
author_rank: Super Contributor
timestamp: June 29, 2015, 04:21:03 pm
content: Quote from: sync on June 29, 2015, 03:12:15 pmThe Hard drive is SE/LVD, but the interface on the host side is only SE, so I have forced the Hard drive to be SE.Irix can't be configured like linux, I have to forget the Seagate Barracuda and buy FujitsuI have 2 workstations1) SE/Narrow2) SE/Wide (it does not work LVD)I need an external HD that can be used by 1) and 2), so the right choice I was thinking was an external HD with the SCSI cables I have posted above.

author: sync
author_rank: Frequent Contributor
timestamp: June 29, 2015, 04:43:57 pm
content: Quote from: legacy on June 29, 2015, 04:21:03 pmWhat is the maximum speed of the controller?QuoteAnd probably running it with 10MB/s bandwidth due the cableing. A NFS mounted NAS could be faster.QuoteWhat workstation models do you have?I have two octanes and a few R10k indigo². But they are collecting dust in the attic.