[Info-vax] OT: the Daily WTF for today is a VAX/VMS story

[Johnny Billquist]

On 2016-02-15 01:28, Kerry Main wrote:
>> -----Original Message-----
>> From: Info-vax [mailto:info-vax-bounces at info-vax.com] On Behalf Of
>> Johnny Billquist via Info-vax
>> Sent: 14-Feb-16 6:50 PM
>> To: info-vax at info-vax.com
>> Cc: Johnny Billquist <bqt at softjar.se>
>> Subject: Re: [New Info-vax] OT: the Daily WTF for today is a VAX/VMS
>> story
>>
>> On 2016-02-15 00:05, William Pechter wrote:
>>> Yup and the RP06's could even share a power socket with a cable DEC
>> shipped
>>> that let a pair of drives daisy-chain the AC power between them.
>>>
>>> And a power sequence cable kept them from trying to power up at the
>> same time
>>> IIRC...
>>
>> You know, I've never seen a power sequence cable for the RP06, but
>> when
>> I was reading the documentation now, the manual mentions the power
>> sequence control. So obviously there must have been a way to connect
>> them together for that purpose.
>>
>> Our DEC-2060 had three RP06, but I cannot remember any power
>> sequencing
>> going on between them. But maybe 3 was considered too few. Or,
>> actually,
>> I think we also had them all on separate fuses...
>>
>> 	Johnny
>>
>
> There was a small 2 or 3 pin signal cable which was strung between
> drive power controllers to enable power-up sequencing.
>
> It was highly recommended best practice, but not mandatory. This was
> not unique to RP's, but was actually used by RMxx/RAxx and numerous
> other drives at the time. I believe you could setup systems powering on
> the same way.
>
> Reason was that these drives had very high startup current and after a
> computer room power failure or just normal power off /on maint work,
> if this sequencing was not in place, then the Data Center UPS/PDS's
> breakers might not be able to deal with the current from all the drives
> restarting at once.

I'm well aware of them for the RA60/80/81/82, and I mentioned them in a 
previous post. But I never saw anything similar for the RP06. But 
something obviously existed, as the manual refers to it. I just never 
saw/used any. I need to go and check an RP06 when I get close to them 
next time, so see if I can find the connector.
For the RA drives, you needed the terminator plug in order to even get 
the drives to spin up. But they were also pretty obvious when you look 
at the back of the drive.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol