Technical data

Using BACKUP
11.15 Backing Up User Disks
11.15.8.1 Mounting a Disk in a Host-Based Shadow Set
To mount a disk in the StorageWorks RAID Array 110 Subsystem in a host-based
shadow set, you must use the /OVERRIDE=NO_FORCED_ERROR qualifier with
the MOUNT command.
The StorageWorks RAID Array 110 Subsystem does not support the
READ/WRITE LONG SCSI commands that are necessary for implementing
the FORCED ERROR function in SCSI. Without FORCED ERROR, you must
override that check by the shadowing driver.
11.15.8.2 Assisted Merging in Mixed-Architecture Clusters
Assisted merging, also known as minimerge, is disabled if shadow sets are
mounted on an OpenVMS Alpha node and also on other types of nodes in the
same cluster. To reenable assisted merging, apply the CSCPAT (TIMA) kit to all
OpenVMS Cluster nodes mounting the shadow set.
With minimerge disabled, shadowing will continue to function normally. However,
a full merge will always be done when a merge operation is required. A full
merge takes considerably longer to complete than a minimerge operation; Compaq
recommends that you install the CSCPAT (TIMA) kit.
11.16 Restoring User Disks
Occasionally you may want to restore the backup copy of an entire disk. For
example, if the disk drive fails, you could restore the backup copy to a working
disk. By occasionally saving and restoring an image backup, you can also prevent
disk fragmentation.
The way in which you restore a disk depends on whether the most recent
backup was an image (full) or incremental backup. Section 11.16.1 describes the
process for restoring a disk when the most recent backup was an image backup.
Section 11.16.2 describes the process for restoring a disk when one or more
incremental backups were performed since the most recent image backup.
11.16.1 Restoring Image Backups
This section describes how to restore the entire contents of a disk when your most
recent backup was an image backup (using the /IMAGE qualifier, as described in
Section 11.15.2).
How to Perform This Task
To restore an image backup, use the following procedure.
Caution
When you use the /IMAGE qualifier in a restore operation, the disk
to which you are restoring the files is initialized. Initializing the
disk removes links to the existing files, effectively erasing them. To
restore individual files or directories rather than the entire disk, see
Section 11.14.
1. Mount the disk to which you will restore the files, using the
MOUNT/FOREIGN command as described in Section 11.8.2.
Using BACKUP 11–45