Conference decwet::winnt-clusters

703.0. "SCSI command timeouts and Storage Blitz" by MSE1::PCOTE (press one now for personal name) Thu Mar 20 1997 17:26

  I'm entering this StorageWorks Blitz in this conference because
  the subject matter relates to supported NT Clusters storage
  configurations. 



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| d | i | g | i | t | a | l |      TIME   DEPENDENT   BLITZ
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      BLITZ TITLE: BA356 enclosures, RZ29B's, RZ28D's , DWZZB-VW's 
                   and SWXA2-BA (MVD) 
 
                                                DATE: November 1, 1996
      AUTHOR: Charles Schnare                   TD #: 
      DTN:237 3639         
      ENET:SUBSYS::SCHNARE  	   		CROSS REFERENCE #'s:
      DEPARTMENT: Adapters and Backplane        (PRISM/TIME/CLD#'s) 
                  Controllers Engineering
                                                
         					
                                                        
      INTENDED AUDIENCE: U.S/EUROPE/GIA		PRIORITY LEVEL: 1 
                         
                                                 (1=TIME CRITICAL,
                                                  2=NON-TIME CRITICAL)
      =====================================================================

Subject : BA356 enclosures, RZ29B's. RZ28D's , DWZZB-VW's and SWXA2-BA (MVD) 


PROBLEM OVERVIEW:
-----------------
  
  Storage  BA356  enclosures using a combination of AC power supplies, 
  DWZZBs, and RZ29Bs or RZ28Ds can exhibit SCSI command time-outs. The 
  result  of  these time-outs is interrupted I/O between the subsystem 
  and the host.
  
  
CONFIGURATIONS AFFECTED:
------------------------
  
  The specific configurations that could be affected are as follows;
     
  	1) BA356 enclosures, utilizing AC power supplies, and a 
           combination  of one (1) DWZZB-VWs and four (4) or more 
           RZ29Bs or RZ28Ds.
  
  	2) BA356 enclosures, utilizing AC power supplies, and a 
           combination  of two (2) DWZZB-VWs and three (3) or more 
           RZ29Bs or RZ28Ds.
  
  
TECHNICAL DETAIL:
-----------------
  
  In  the  above  mentioned  subsystem configuration,  the  cumulative
  voltage  drops  across  the  subsystems  power  distribution  system
  (which  includes the power supply, backplane, loads,  flex  circuit,
  and DWZZB-VW itself) can cause the low voltage sensor  on the DWZZB-
  VW  to trigger. This will cause the SCSI bus to go into a bus   free
  state  on  the target side, resulting in SCSI bus command time-outs.
  The  nature of the problem is such that some of these configurations
  will in fact operate error free.
  

  AFFECTED SERIAL NUMBER RANGE: N/A; Rev A02 DWZZB-VW units.
                                     Rev A02 SWXA2-BA (MVD)
  
Short Term Work Arounds:
------------------------
  
  Corrective  action is only required IF you have a storage  subsystem
  matching  the above configurations AND it is exhibiting  the  system
  symptoms described above. There are two proposed work arounds.
  
        1. Add a Second Power Supply. We have found that in most cases
           adding a second power supply will correct the problem.
  
        2. Depopulate  the BA356 enclosures to one (1)  DWZZB-VW  and
           four  (4)  RZ29Bs or RZ28Ds or depopulate BA356 enclosures  
           with two (2) DWZZB-VW's and three (3) RZ29Bs or RZ28Ds.
  
  
Long Term Solution:
-------------------
  
  Corrective  action is only required IF you have a storage  subsystem
  matching  the  above  configurations AND its exhibiting  the  system
  symptoms described  above. There is one long term solution.
  
       1. Replace the Rev A02 DWZZB-VW units with, Rev B01 DWZZB-VW.
  
NOTE: This  ECO work  has  just started in manufacturing. It  will  be 
      some  number  of weeks before ECO'd units will be  available  at
      your  local  field  service  stockrooms.  Short  term  solutions
      listed   above   will  correct  the  problem  until   there   is
      availability in the field service stockrooms.