From: bqt@softjar.se   
      
   On 2025-12-03 01:25, Rich Alderson wrote:   
   > =?UTF-8?Q?Arne_Vajh=C3=B8j?=  writes:   
   >   
   >> On 12/1/2025 6:56 PM, Rich Alderson wrote:   
   >>> =?UTF-8?Q?Arne_Vajh=C3=B8j?=  writes:   
   >>>> On 12/1/2025 1:02 PM, Scott Dorsey wrote:   
   >>>>> There are many devices that should be preserved in working condition so   
   that   
   >>>>> new generations should see how they worked when they were new and   
   experience   
   >>>>> them working.  The RA81 should be left in the rack broken, so that new   
   >>>>> generations can see how they were when they were new.   
   >>>   
   >>>> RA81's and RA82's on a 8650.   
   >>>   
   >>>> The RA82's were okay, but the RA81's crashed frequently. DEC field   
   >>>> service knew that site very well.   
   >>>   
   >>>> I have been told here that there were a manufacturing problem with   
   >>>> RA81's and when the problem got fixed they stopped crashing all the   
   >>>> time.   
   >>>   
   >>> You've got the RA81 and RA82 backwards.  We had RA81s on a CI cluster at   
   >>> Stanford, and they were pretty solid.   
   >>>   
   >>> RA82s were not available for the 36 bit systems, but we heard about them   
   from   
   >>> our DEC FEs.   
   >>   
   >> I could easily remember it wrong - it has been a long time.   
   >>   
   >> But a search in c.o.v confirmed that it was the RA81's.   
   >>   
   >> 2003 post:   
   >>   
   >>    
   >> The problem with the RA81's wasn't that the drives were really flaky --   
   >> there were some early data and noise problems ECO's out under warranty   
   >> early on -- but that the glue that held the HDA filter was substituted   
   >> without a close look at the specifications of the glue.   
   >>   
   >> The substituted glue on HDA's at Rev F (IIRC) would liquify at warm   
   >> temperatures and flow to the bottom of the HDA and crash head 13   
   >> into the bottom platter every time.   
   >>    
   >>   
   >> 2021 post:   
   >>   
   >>    
   >> The early RA81s had a problem where the heads would "unglue" from the   
   >> actuator and totally trash the disk.   
   >>   
   >> DEC actively hunted out and replaced those original drives. The   
   >> replacement RA81s were good and ran forever.   
   >>    
   >   
   > Odd.  That's exactly what I remember about the RA82!   
      
   Odd indeed. Because I also remember it as being an RA81 problem.   
   I bet if you were to search through the internet about RA81 and glue,   
   you'll find lots of references. I didn't remember it being the filter as   
   such, but some other part. But that hardly matters. Later the problem   
   got fixed, and by the time of the RA82 it was all sorted.   
      
   And I also must say that I've never really had any problems with RA81 or   
   RA82 drives. But then again, by the time I was dealing with the hardware   
   myself, the glue problem was long solved.   
      
      Johnny   
      
   --- SoupGate-Win32 v1.05   
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