skip book previous and next navigation links
go up to top of book: HP Volume Shadowing for OpenVMS HP Volume Shadowing for OpenVMS
go to beginning of chapter: Creating and Managing Shadow Sets Using DCL Commands Creating and Managing Shadow Sets Using DCL Commands
go to previous page: Allocating Devices Allocating Devices
go to next page: Using INITIALIZE/SHADOW/ERASE to Streamline the Formation of a Shadow SetUsing INITIALIZE/SHADOW/ERASE to Streamline the Formation of...
end of book navigation links

Creating a Shadow Set   



To create a shadow set, you must use the MOUNT command with the /SHADOW qualifier to mount at least one physical disk into a shadow set and assign a virtual unit name to the set, as shown in Creating a Shadow Set.
Example 1  Creating a Shadow Set   


$ MOUNT DSA23: /SHADOW=$4$DUA9:volume-label logical-name




This example forms a shadow set represented by the virtual unit DSA23, and includes one shadow set member, $4$DUA9. To create a shadow set, you must observe the following rules:

In addition, you can specify /SYSTEM, /GROUP, or /CLUSTER to make the shadow set available to all users of a system, all members of a group, or all nodes in a cluster on which shadowing is enabled.

To create a three-member shadow set, you can add two members in a single MOUNT command to an existing one-member shadow set. This method optimizes the I/O operation because both members are copied at the same time. (See the example in Creating a Shadow Set With /SYSTEM and With /CLUSTER.)

You can also streamline the process of creating a shadow set by initializing multiple devices in one command, using INITIALIZE/SHADOW/ERASE, as described in Using INITIALIZE/SHADOW/ERASE to Streamline the Formation of a Shadow Set.

Upon receiving a command to create a shadow set, the volume shadowing software may perform a copy or a merge operation to reconcile data differences. If you are not sure which disks might be targets of copy operations, you can specify the /CONFIRM or /NOCOPY qualifiers as a precaution against overwriting important data when you mount a disk. These and other MOUNT command qualifiers are discussed in MOUNT Command Qualifiers for Shadowing.


go to previous page: Allocating Devices Allocating Devices
go to next page: Using INITIALIZE/SHADOW/ERASE to Streamline the Formation of a Shadow SetUsing INITIALIZE/SHADOW/ERASE to Streamline the Formation of...