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Using $MOUNT to Create and Mount Shadow Sets  



You can create and mount shadow sets using the $MOUNT system service in a user-written program. Program calls to $MOUNT that create, mount, or add devices to shadow sets use the same syntax. To direct the system to perform any mount operation, you construct a $MOUNT item list. The item list specifies the virtual unit that represents the shadow set and the members (physical devices) that the shadow set contains.

The call to the $MOUNT system service has the following format: SYS$MOUNT itmlst

Item List to Create and Mount a Shadow Set illustrates MACRO-32 statements that produce a $MOUNT system service item list to create and mount a shadow set.
Example 1  Item List to Create and Mount a Shadow Set  
DSA23:  .ASCID /DSA23:/
MEMBER001:   .ASCID /$4$DUA9:/
MEMBER002:   .ASCID /$4$DUA5:/
 
VOLUME_LABEL:  .ASCID /MYVOLUME/
VOLUME_LOGNM:  .ASCID /DISK$MYVOLUME/
 
        .MACRO   .ITEM, SIZE, CODE, BUFFER, RETURN=0
        .WORD    SIZE, CODE
        .ADDRESS BUFFER, RETURN
        .ENDM    .ITEM
 
ITMLST: .ITEM   6,  MNT$_SHANAM, DSA23 
        .ITEM   8,  MNT$_SHAMEM, MEMBER001 
        .ITEM   8,  MNT$_SHAMEM, MEMBER002
 
        .ITEM   8,  MNT$_VOLNAM, VOLUME_LABEL  
        .ITEM   13, MNT$_LOGNAM, VOLUME_LOGNM  
         .LONG   0


The following list describes the elements in Item List to Create and Mount a Shadow Set:

.

Later, if you want to add another device to the shadow set, you make another call to $MOUNT that specifies an item list that contains the name of the virtual unit and the name of the device you want to add to the shadow set. Item List to Add a Member to a Shadow Set shows how to add the physical device $4$DUA10: to the shadow set created in Item List to Create and Mount a Shadow Set.
Example 2  Item List to Add a Member to a Shadow Set  
DSA23:  .ASCID /DSA23:/
 
MEMBER003:  .ASCID /$4$DUA10:/
VOLUME_LABEL:  .ASCID /MYVOLUME/
VOLUME_LOGNM:  .ASCID /DISK$MYVOLUME/
 
        .MACRO   .ITEM, SIZE, CODE, BUFFER, RETURN=0
        .WORD    SIZE, CODE
        .ADDRESS BUFFER, RETURN
        .ENDM    .ITEM
 
ITMLST: .ITEM   6,  MNT$_SHANAM, DSA23  
 
        .ITEM   9,  MNT$_SHAMEM, MEMBER003
        .ITEM   8,  MNT$_VOLNAM, VOLUME_LABEL 
        .ITEM   13, MNT$_LOGNAM, VOLUME_LOGNM 
        .LONG   0


$MOUNT Shadow Set Item Codes briefly describes the $MOUNT shadow set item codes and discusses how to construct a valid $MOUNT item list. For a complete description of the $MOUNT service and all its item codes, refer to the HP OpenVMS System Services Reference Manual.


 
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