Technical data

Using BACKUP
11.15 Backing Up User Disks
11.15 Backing Up User Disks
This section explains performing incremental and image backups to disk and
tape.
Note
Do not use the menu system (which displays when you boot the OpenVMS
VAX operating system CD–ROM) to back up user disks. Use the menu
system to back up system disks only.
In addition, if you back up large user disks on VAX systems, BACKUP
might need to page and thereby cause the operation to fail. If this occurs,
use online BACKUP to back up those VAX user disks.
11.15.1 Preparing to Back Up User Disks
Compaq recommends that you back up your disks with no interactive users logged
in and with no applications running. This is because if BACKUP encounters an
open file during a save operation, it issues an error message and does not copy
the file. Also, because of the way BACKUP scans directories, any activity in a
directory (such as creating or deleting files) can cause files to be excluded from
the backup.
Note
The first time you back up a disk, you must perform an image backup
using the BACKUP/IMAGE/RECORD command before you perform
regular incremental backups. The image backup saves a copy of the
entire disk and marks each file as being saved. Subsequent incremental
backups assume that an image backup has been performed; only new or
modified files are saved.
If an image backup is not performed first, the incremental backups save
more files than might be necessary to ensure that an incremental restore
operation will be successful.
You can instruct BACKUP to save open files by using the /IGNORE=INTERLOCK
qualifier on the BACKUP command, as described in Section 11.18.3. However,
open files saved by BACKUP might contain inconsistent data, depending on the
applications that are writing to the open files. BACKUP reports a message if
either:
• The file was modified while BACKUP was reading the file
• The file is accessed for writing on the local node when BACKUP finishes
reading the file
However, if the file is accessed for writing from a remote node when BACKUP
finishes reading the file, no message is displayed because BACKUP cannot detect
the access.
If a file with the specified version already exists, BACKUP reports the following
error message:
RMS-E-FEX, file already exists, not superseded
11–32 Using BACKUP