Air Cleaner User Manual

The backup command, however, has changed over time in how it backs up and
restores “sparse” files. A sparse file is a file in which blocks of data have been
written non-sequentially, leaving unallocated blocks in the middle of a file.
Previous levels of the backup command did not preserve this sparseness, and a
sparse file, when restored, expands to include all blocks in the middle of the file,
often causing a filesystem to inadvertently run out of space. The backup command
was later changed to preserve this sparseness, but this is often a problem for
customers experiencing the opposite affect.
If a file is created and all blocks are allocated by writing nulls, or “0s,” throughout
the file, these blocks of data are not preserved during a restore, because the goal is
to preserve sparseness. Because of this, a large file might be restored to a very
small size.
SysBack enables you to select the command you want to use to perform backups.
This can be either the AIX backup and restore commands (which preserve
sparseness) or the tar command (which does not).
End of Tape (EOT) Processing Options
This feature will allow you to specify a network e-mail address, or program to
execute, when the end of volume is reached during backup and restore operations.
For multi-volume backups, each time the end of tape is reached the configured
option will be executed. If you configure this option and have an autoloading
device that automatically loads the next tape for you, these actions will still be
executed even if no action is required. An example might be in an environment
where you would like an e-mail sent at each tape change, even thought the library
is changing tape for you in order to have an easy reference indicating the number
of volumes in any given backup.
This function is particularly useful in environments that have robotic libraries that
require special commands or software to mount and dismount tape volumes. Since
SysBack does not interact or control the medium changer in a library, this allows
you to create a script that will issues the commands for SysBack for each tape
change during a backup or restore.
There are 4 options that can be set to affect the end of tape processing. These are
configured on the SysBack server where the tape library is physically attached.
Program For EOT on Write Operations.
Specify an e-mail address to send the message to when end of tape has
been reached (triggered by the sbwrite command). This option only affects
backup operations.
Program For EOT on Read Operations.
Specify an e-mail address to send the message to when end of tape has
been reached (triggered by the sbread and sbfwd commands). This option
only affects restore, list, and verify operations. The e-mail title will be like
this:
SysBack Tape Change on host "sysback1" for Tape Drive /dev/rmt0 Tape 2
The body would contain this information:
HOST sysback1
TAPE_DRIVE /dev/rmt0
TAPE 2
Chapter 16. Utilities 16-23