[Info-vax] DEC Multia (UDB) issues

[Stafford Winters]

On 8/22/2011 9:02 AM, MG wrote:
> On 22-8-2011 17:24, Stafford Winters wrote:
>> I'd look at SCSI bus length and termination, and then maybe termination
>> power.
>
> The setup was as follows: There was only one device connected each
> time.  The RRD43 at first and later the earlier mentioned Yamaha
> CRW4260tx CD-R/RW drive.  Both were connected with cables well below
> 2 m (about 1 ~ 1½ m / 3 ~ 5 ft, on average).
>
> The termination didn't seem to be the problem, because both devices
> were properly recognized in the SRM and would actually work up to a
> certain point.  Whenever I tried to boot up one of the VMS CDs, I
> got one error that suggested that the SCSI controller 'isn't ready.'
I've see a few strange things happen in the past, and inconsistently, 
when a device had internal termination and there was also an external 
terminator.  The device would work for a while and then stop working for 
a while and start working again, but just for a while.

I've also seen devices exhibit similar behavior, and the problem was 
corrected by setting a jumper on the device to "provide termination 
power."  This particular situation was one where there were several 
devices on the bus.

These situations were with VAXen.  I don't recall ever having problems 
with the 30+ AlphaServers I configured, but then they were all assembled 
with new parts, where the disks were all SBB, the tape drive was 8mm, 
and the CD ROM drive was probably only used occasionally after the 
initial installation.

It's also worth swapping the SCSI cabling, if you have another set 
available.

Tad
>
>  - MG
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