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Conference smurf::ase

Title:ase
Moderator:SMURF::GROSSO
Created:Thu Jul 29 1993
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2114
Total number of notes:7347

1952.0. "SCSI BUS PROBLEM" by DAIVC::TEGUH () Mon Mar 17 1997 21:15

    guys, 
    
    
    Most of my customer is using DECsafe environment, as we know that
    DECsafe is designed to minimize down time due to hardware/software
    failure or single point of failure. But, I got bad experience with scsi
    bus problem a week ago.That is the issue which I still don't
    understand, how come if we got the problem on scsi bus all members got
    panic. Logicaly is correct, because when we have a problem on the scsi
    bus such as U-cable, tri-link connector, Y-cable or BN21K cable, the
    scsi bus system would be unterminated and causing panic on all members.
    This is one of my customer configuration :
    
                           H885-AA
          BN21W-0B         BN21L-0B           BN21W-0B
      --------- BN21K-20   -------  BN21K-20  --------
     |         |----------|       |----------|        |
     |AS2100   |----------|SW800  |----------|AS2100  |
      ---------            -------            --------
          BN21W-0B         BN21L-0B           BN21W-0B
                           H885-AA            
     
     By looking above figure, I see a lot of single failure on that
    configuration on the scsi bus system.
    
    My questions are :
    
    - Is there any way to solve this kind of problem ? because it took
    a long time to trace problem on that.
    - Why the error messages came up and scrolled up everytime there is failed 
    disk on the SW800 subsystem ? because it made system hung sometimes.
    - Can anyone let me know what the exact use of ASE_PARTIAL_MIRRORING
    parameter ? detail please .
    
    I thinks that's it for this time, I still a lot of questions on my mind
    which I intend to share to all you guys.
    
    thanks in advance.
    
    TW
T.RTitleUserPersonal
Name		DateLines
1952.1SCSI bus config does not look rightNETRIX::"[email protected]"Grgeory P. MyrdalWed Apr 02 1997 12:0728
Hi,

Maybe its my interpretation of your diagram, however, I do not see your 
SCSI bus config as being correct.  You might want to draw another more
accurate picture if you want to get answers about possible SCSI problems.

                           H885-AA
          BN21W-0B         BN21L-0B           BN21W-0B
      --------- BN21K-20   -------  BN21K-20  --------
     |         |----------|       |----------|        |
     |AS2100   |----------|SW800  |----------|AS2100  |
      ---------            -------            --------
          BN21W-0B         BN21L-0B           BN21W-0B
                           H885-AA 
           
Questions that came to my mind are:  

1) Is there only one KZPSA, if so, why do you have two  BN21W-0B listed
   per system?
2) How are the BN21W-0B's terminate?
3) Are there two scsi buses from the AS2100 to the SW800?
4) Where does the BN21L-0B's hook into the config?
5) Why are there no H879-AA's listed?

Please provide a more accurate picture.  Thank you.

-- greg
[Posted by WWW Notes gateway]
1952.2Bus length?SMURF::KNIGHTFred KnightWed Apr 02 1997 16:586
Yes, a new picture would be nice.  The one that you have in
.0 shows a scsi bus of over 40 meters.  That is ILLEGAL.  The
maximum length of a differential bus is 25 meters (end to
end).  So, please explain how you really have it wired.

	Fred
1952.3change note address to 1979.0DAIVC::TEGUHWed Apr 02 1997 23:028
    sorry guys, I put it in the wrong notes please refer to  1979.0 for the
    answer.
    
    
    thanks 
    TW
1952.4MORE PICTURE INFORMATION AND WAIT for ANSWERDAIVC::TEGUHThu Apr 17 1997 04:0752
    guys,
    
    thanks in advance for your responses. I'll give the detailed diagram of
    my configuration.
    The DECsafe configuration  is :
    - 2 AS2100
    - 1 SW800 
    
    Each Host :
    -----------
    - 2 KZPSA   (internal differential terminator removed)
    - 2 BN21W-0B 
    - 2 H879-AA
    - 2 BN21K-10
    
    SW800 :
    -------
    - 4 HSZ40  (2 dual-redundant)
    - 2 H885-AA
    - 1 BN21L-0B
    
    And the diagram is :
    
     H879-AA                H885-AA                    H879-AA
     BN21W-0B               BN21L-0B                   BN21W-0B
     2 KZPSA                2 HSZ40 (dual-redundant)   2 KZPSA
     ---------    BN21K-10  --------    BN21K-10    --------
    |         |------------|        |--------------|        |
    | AS2100  |            | SW800  |              | AS2100 |
    |         |------------|        |--------------|        |
     ---------    BN21K-10  --------    BN21K-10    --------
     2 KZPSA                 2 HSZ40 (dual-redundant)  2 KZPSA
     BN21W-0B                BN21L-0B                  BN21W-0B
     H879-AA                 H885-AA                   H879-AA
    
    
     I think that's it and I hope the picture is nice already.
     So... I'm waiting for your responses guys ASAP..
    
    
    
    rgds
    
    TW