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Conference ssag::ask_ssag

Title:	Ask the Storage Architecture Group
Notice:	Check out our web page at http://www-starch.shr.dec.com
Moderator:	SSAG::TERZAN

Created:	Wed Oct 15 1986
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	6756
Total number of notes:	25276

6515.0. "Query on Shelf_OK signal on BA356" by CGOU28::MCARA (John McAra) Tue Mar 25 1997 15:29

I have a question regarding the SHELF_OK signal on a BA356.  The BA356 is
configured in split bus mode with a 16bit personality module.  Half of the
backplane is connected to a KZPSC which requires the SHELF_OK to be enabled and
the other half is connected to a KZPDA which does not.

Regardless of whether the SHELF_OK jumper is installed or not on the backplane,
the SWXCR Monitor is reporting shelf errors.

Since there is only one jumper for this signal on the backplane and the user's
guide indicates that it goes to both connectors on the personality card, I am
speculating that my problem is that the KZPDA is grounding the signal.

Is there a solution to this other than having the customer order another BA356?

T.R	Title	User	Personal Name	Date	Lines
6515.1		HOUNDD::BASSETT	Bill	`Tue Mar 25 1997 16:38`	15
	John, You are correct - Shelf_OK for split bus is common for both buses. And if one initiator grounds the Shelf_OK line, the other initiator will think that there is a Shelf_OK problem since the line is being pulled low. The shelf Shelf_OK jumper has no impact on this since the "Y" takes place at the backplane to personality card connector. The only KNOWN solution is to cut the wire in the cable going to the KZPDA. (or pull the pin or whatever it takes to remove the ground from Shelf_OK.) Or get two shelves.... Bill
6515.2	Me too !!!	KAOFS::ras022p07.mqo.dec.com::D_ORMAECHEA		`Tue Mar 25 1997 19:51`	14
	I have reported this same situation in the Alphaserver_4100 conference, note 534. I have two sites with the same issue, and i think that the problem is exactly what is described in the previous reply. Can somebody give us the info to know what cable pins to cut. I also presume that we can use the Storageworks terminators (with the cutted pins) as a reference ?. Thanks ! Denis Ormaechea Montreal MCS.
6515.3		CGOU28::MCARA	John McAra	`Wed Mar 26 1997 08:30`	7
	Bill, Thanks for the quick response in confirming what I suspected. I will pass the info on and find out which approach the customer's wants to take, I will be recommending the second BA356 approach. John
6515.4		HOUNDD::BASSETT	Bill	`Wed Mar 26 1997 09:39`	12
	re: .2 Denis, From the schematic - at Connector JA and JB (both 68 pos connectors) on the personality card - shelf OK uses pin 50. Be careful with using the StorageWorks(tm) terminators as your reference. Shelf_OK is not the only line open. OK? Bill
6515.5	Yup !	KAOFS::ras022p03.mqo.dec.com::D_ORMAECHEA		`Fri Mar 28 1997 19:09`	2
	Thanks !