Technical data

System Management Features
4.13 Volume Shadowing for OpenVMS
For more information about this new feature, including additional memory
requirements for this version of Compaq Volume Shadowing for OpenVMS, refer
to Volume Shadowing for OpenVMS.
4.13.2 New Volume Shadowing Features for Multiple-Site OpenVMS Cluster
Systems
OpenVMS Version 7.3 introduces new command qualifiers for the DCL commands
DISMOUNT and SET for use with Volume Shadowing for OpenVMS. These
new command qualifiers provide disaster tolerant support for multiple-site
OpenVMS Cluster systems. Designed primarily for multiple-site clusters that use
Fibre Channel for a site-to-site storage interconnect, they can be used in other
configurations as well. For more information about using these new qualifiers
in a multiple-site OpenVMS Cluster system, see the white paper Using Fibre
Channel in a Disaster-Tolerant OpenVMS Cluster System, which is posted on the
OpenVMS Fibre Channel web site at:
http://www.openvms.compaq.com/openvms/fibre/
The new command qualifiers are described in this section. Section 4.13.2.1
describes how to use these new qualifiers.
DISMOUNT/FORCE_REMOVAL ddcu:
One new qualifier to the DISMOUNT command, DISMOUNT/FORCE_REMOVAL
ddcu:, is provided. If connectivity to a device has been lost and the shadow set
is in mount verification,
/FORCE_REMOVAL ddcu: can be used to immediately
expell a named shadow set member (ddcu:) from the shadow set. If you omit this
qualifier, the device is not dismounted until mount verification completes. Note
that this qualifier cannot be used in conjunction with the /POLICY=MINICOPY
(=OPTIONAL) qualifier.
The device specified must be a member of a shadow set that is mounted on the
node where the command is issued.
SET DEVICE
The following new qualifiers to the SET DEVICE command have been created for
managing shadow set members located at multiple sites:
•
/FORCE_REMOVAL ddcu:
If connectivity to a device has been lost and the shadow set is in mount
verification, this qualifier causes the member to be expelled from the shadow
set immediately.
If the shadow set is not currently in mount verification, no immediate action
is taken. If connectivity to a device has been lost but the shadow set is not in
mount verification, this qualifier lets you flag the member to be expelled from
the shadow set, as soon as it does enter mount verification.
The device specified must be a member of a shadow set that is mounted on
the node where the command is issued.
•
/MEMBER_TIMEOUT=xxxxxx ddcu:
Specifies the timeout value to be used for a member of a shadow set.
The value supplied by this qualifier overrides the SYSGEN parameter
SHADOW_MBR_TMO for this specific device. Each member of a shadow
set can be assigned a different MEMBER_TIMEOUT value.
The valid range for xxxxxx is 1 to 16,777,215 seconds.
System Management Features 4–21