Technical data

Using BACKUP
11.13 Backing Up Files and Directories
10. If you are backing up more data than the output volume can contain, mount
the output volume using the /FOREIGN qualifier and create a sequential disk
save set. For example:
$ MOUNT DUA1: PAYROLL
%MOUNT-I-MOUNTED, PAYROLL mounted on _DUA1:
$ MOUNT/FOREIGN DJA21:
%MOUNT-I-MOUNTED, WEEKLY mounted on _DJA21:
$ BACKUP
From: DUA1:[PAYROLL]
To: DJA21:[PAYROLL_BACKUPS]PAY22MAY2000.SAV/SAVE_SET
In this example, if the contents of the [PAYROLL] directory exceed the
capacity of the disk DJA21:, BACKUP prompts you to remove the volume in
the drive and insert another one. For more information about Files–11 and
sequential disk save sets, see Section 11.5.
Note
Prior to OpenVMS Version 7.2, 32 levels of directories were supported.
Beginning with OpenVMS Version 7.2 on VAX and Alpha systems,
the number of levels of directories can be as high as RMS allows; for
OpenVMS Version 7.2 and later, that number is 255 levels.
11.13.3 Comparing Files
A BACKUP compare operation compares a save set with disk files or compares
disk files with other disk files. Perform a compare operation to check the integrity
of a file or volume after a copy, save, or restore operation. For example, you can
use the compare operation to compare a save set with original files or to compare
files or volumes copied using BACKUP with original files.
Note
Because BACKUP processes files by blocks, comparing files not produced
by BACKUP is likely to cause mismatch errors in files that are apparently
identical.
How to Perform This Task
The two ways to perform a compare operation are:
• You can perform a compare operation in conjunction with a save, restore,
copy, or list operation by specifying the command qualifier /VERIFY. When
you specify /VERIFY, BACKUP first performs the save, restore, copy, or
list operation and then compares the output with the input. When you use
/VERIFY in a copy or list operation, BACKUP displays no message when it
begins the compare operation. When you use /VERIFY in a save or restore
operation, BACKUP displays the following message when it begins the
compare operation:
%BACKUP-I-STARTVERIFY, starting verification pass
• You can perform a compare operation independently of other BACKUP
operations by specifying the command qualifier /COMPARE. In addition,
you can use the /COMPARE and /IMAGE qualifiers to instruct BACKUP to
perform an image compare operation. This operation compares files on two
different disks by using the file identifications (FIDs).
Using BACKUP 11–27