[Info-vax] Unpleasant Disk Shadowing Surprise

[VAXman- at SendSpamHere.ORG]

In article <40ef058b-f66b-48dd-835d-a7824e0241ae at t6g2000vba.googlegroups.com>, tadamsmar <tadamsmar at yahoo.com> writes:
>On Oct 12, 6:40=A0am, VAXman-  @SendSpamHere.ORG wrote:
>> In article <168e7442-2c78-4dda-8942-6f831d954... at d28g2000vby.googlegroups=
>..com>, tadamsmar <tadams... at yahoo.com> writes:
>>
>>
>>
>>
>>
>> >On Oct 11, 4:16=3DA0pm, Kenneth Fairfield <ken.fairfi... at gmail.com> wrot=
>e:
>> >> On Tuesday, October 11, 2011 11:53:12 AM UTC-7, tadamsmar wrote:
>>
>> >> [...]
>>
>> >> > Here is what I find in the error log:
>>
>> >> > I had two errors on the pka0: (adaptec aic-7899) at times 7:58:14 an=
>d
>> >> > 7:58:21
>>
>> >> I was more interested in what SHOW DEVICE DK shows
>> >> for the members of the shadow set in question. =3DA0Errors
>> >> on the PK device are not terribly interesting most of
>> >> the time (they tend to come in ones and twos at boot
>> >> time, etc.).
>>
>> >> Of course once you've done a dismount on bad disk,
>> >> the count gets reset.
>>
>> >> But as others have noted, having both shadow members
>> >> on the same scsi bus is problematic. =3DA0A single "bad"
>> >> error on the one disk can hang the whole bus...
>>
>> >> =3DA0 =3DA0 -Ken
>>
>> >I looked at SHOW DEVICE DK. =A0I now see that I did not read it
>> >correctly earlier, and I have been confused about some things.
>>
>> >The real sequence of events is that DKA100 went offline and DKA0
>> >logged an error at almost exactly the same time! Those are my shadow
>> >set. Hopefully that was a soft error on DKA0 so that my data is not
>> >compromised, I need to double check that.
>>
>> >I rebooted just before I left work and DKA100 did not even show up
>> >after the reboot.
>>
>> >I am now thinking that I probably have a bad SCSI cable. =A0I will
>> >replace that tomorrow, I think I have one in storage.
>>
>> >We have a single pass HVAC system in our building so the ozone levels
>> >are close to outdoor levels and this tends to eat the insulation on
>> >cables.
>>
>> Where in the world are you that you have cable eating ozone levels?
>>
>
>It's a research center with lots of labs.  It has a single pass air
>handling system.  Whereas most offices and homes have a recirculation
>system.
>
>Ozone get created in sunlight and it reacts away pretty quickly so a
>typical home or office has a very low level of ozone inside.  A
>building with a single pass system has ozone levels pretty close to
>the levels outside the building.
>
>I had to replace one god awful looking SCSI cable with obvious exposed
>copper wires.  There is a general belief here that ozone is a problem
>for all sorts of components in our building, but I am not an expert on
>the matter.

I'm so happy you didn't answer the question.

-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

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