Conference vaxaxp::vmsnotes

>1) Can I have the same unit number on disk1 and disk2 ?

Yes.

2) If yes, how can I do that ?

Sure, give each system a unique allocation class.

Jur.

re .1:

>... give each system a unique allocation class.

Um, that'll be ill-advised given the shared devices.

:   My customer buys two ALPHA 4100 systems and runs ALPHA VMS V6.2. His 
:configuration is listed as follows:

   Note: the customer *must* run V6.2-1H3, or V7.1.  V6.2 will *not* work.

   One must have unique unit numbers across all disks within any particular
   disk allocation class (zero or non-zero), and across all tapes within any
   particular tape allocation class (zero or non-zero).

   Shared storage interconnects normally require the use of the same
   non-zero allocation class and unique unit numbers, to uniquely and
   explicitly identify all direct and served paths to a particular device
   with a particular unit number as being different paths to the same
   device, and not as different devices with overlapping unit numbers.

   This particular configuration is one of the reason why OpenVMS Alpha
   V7.1 added port-level allocation classes.

   I'd recommend an upgrade to V7.1, or I'd split the SCSI bus, or I'd
   use unique device unit numbers.

   If the customer decides to not upgrade, and to use seperate non-zero
   allocation class numbers on the two Rawhide systems, they must still
   keep the unit numbers on each Rawhide unique, and they will loose the
   ability to fail-over served access to the shared SCSI between the two
   Rawhide systems. 

   If the customer chooses to use overlapping unit numbers and disjoint
   allocation classes, the customer must avoid mounting any disks on the
   shared SCSI that are mounted by the other Rawhide system.  Attempts
   to share disks are likely to result in severe data corruptions on
   the shared disks.

   I would not recommend this disjoint-allocation-class configuration.
   I would configure unique unit numbers, and would place both Rawhide
   systems into the same allocation class.  If I cannot change the disk
   unit numbers, I'd look to upgrade to OpenVMS Alpha V7.1, and use the
   port-level allocation class support.

   And SPEZKO::CLUSTER is a better spot for VMScluster questions...

    Just because Steve didn't really tell you how to use port allocation
    classes...
    
    The SCSI bus with the non-shared devices should get a port allocation
    of 0.  This turns the device name into "node$ddcu". for these devices
    _regardless_ of the system allocation class.
    
    If the shared SCSI bus has the same controller letter on both systems,
    you can give both systems the same allocation class.  If the controller
    letter differs, the bus must get the same port allocation class > 0 on
    both systems.  This will turn the device name into $n$dka... cluster
    wide.
    
    For V7.1, if you use port allocation classes at all on a system, the PKA
    bus must have a port allocation class, either zero or positive.  I am
    currently working on a fix that will allow to lift this restriction.
    
    
    -andy

    Port allocation classes only exist for V7.1, correct?
    
                Mark d.

:    Port allocation classes only exist for V7.1, correct?

   Port allocation class support exists in V7.1 and later.