HP Volume
Shadowing for OpenVMS does not depend on specific hardware in order
to operate. All shadowing functions can be performed on VAX and
Alpha systems running the OpenVMS operating system. Shadow set members
must have the same physical geometry (that is, the same number of
identical logical blocks [LBNs]) and members can be located anywhere
in an OpenVMS Cluster.
Supported Hardware Volume shadowing
requires a minimum of one VAX computer, one mass storage controller,
and DSA (DIGITAL Storage Architecture) or Small Computer System
Interface (SCSI) disk drives.
Refer to the most recent Volume Shadowing for OpenVMS Software
Product Descriptions (SPD 27.29.xx )
for additional information about hardware requirements.
Compatible Disk Drives and Volumes Volume
shadowing requires compatibility among the physical units (disk
drives and volumes) that form a shadow set. For example:
Units must be Files-11 On-Disk Structure
Level 2 (ODS-2) data disks.
Units and controllers must conform to DSA and OpenVMS
MSCP, or must be SCSI compliant.
Units should not have
hardware write protection enabled. Hardware write protection stops
the volume shadowing software from maintaining identical volumes.
However, the shadow set virtual unit may be mounted software write-locked
with the /NOWRITE qualifier to MOUNT.
HP OpenVMS I/O User's Reference Manual
Shadow-Set Virtual Unit Driver
