[lug] SCSI weirdness

[D. Stimits]

Alberto Squassabia wrote:
> Hi there.  Some wisdom on the following issue is
> welcome.
> 
> A SCSI tower has nine LVD Wide SCSI devices, ID are
> 0,1,2,3,4,5,6,8,9.  The disks are SCA devices, mounted
> with 9 SCA-to-68 adapters. All except 3 are recognized
> by the controller.  3 is really flaky, sometimes it
> works, sometimes it does not.  I replaced the spindle
> with a new one.  Same behavior.  I replaced the SCA
> adapter with a new one.  Same behavior.  I unplugged
> the ribbon cable from the SCA adapter, and made a
> jumper with a spare ribbon from the external female
> end to the SCA adapter, connecting to the female of 
> the spare ribbon.  Same behavior.  Any ideas?
> 
> Incidentally, the controller (a DAC960PL1 Mylex) seems
> puzzled that there are more than 8 devices (when
> 3 works, that is).  Is there some magic about at most
> 8 devices on the bus?
> 

This probably is not it, but could the controller or a backplane device 
be competing for SCSI ID 3? I guess there wouldn't be a backplane since 
you use SCA-68 adapter. A miner check would also be whether the power 
supply is able to handle all of those drives...the surge current at 
startup needs to be able to support all of the drives at once.

D. Stimits, stimits AT comcast DOT net