Chris Tyler - Fedora Linux

A multilevel scheme permits you to go back farther in time. A simple three-level scheme (known as Grandfather/Father/Son ) is shown in Table 6-6 .

Table 6-6. Grandfather/Father/Son backup scheme with 20 discs/tapes

This scheme uses the same 20 discs or tapes, but permits you to restore to:

 Any weekday in the preceding week

 The end of any week in the preceding four weeks

 The end of any four-week period in the preceding year

Note that level A media will be more frequently used than level B or C media and will therefore need to be replaced more often.

You must also decide where and how you will store your media. Unless the media is stored offsite, a disaster such as fire or theft could result in the loss of both the original storage drives and the backup media, but storing media offsite will slow the restoration process.

There are many ways of labeling backups, but one of the easiest is to create a file named system- in the root directory immediately before producing the backup, and include that as the first file in the backup volume:

# touch /system-$(hostname)

# ls -l /system-*

-rw-r--r-- 1 root root 0 Jul 1 01:34 /system-bluesky.fedorabook.com

This will identify the originating system name as well as the date and time of the backup (from the file timestamp).

To back up data to DVD, use the growisofs command:

# growisofs -Z /dev/dvd -RJ -graft-points /etc=/etc /home=/home /system-*

This will back up the /etc and /home directories to /dev/dvd (the default DVD recorder). -Z indicates that this is the first session on the disc, and -RJ enables long filename handling compatible with Unix/Linux (Rock Ridge) and Windows (Joliet) systems. The graft-points option permits the backed-up directories to be stored in specific directories on the disc. /etc=/etc and /home=/home specify the directories to be backed up, ensuring that each directory is placed in a directory with the same name on the disc. The argument /system-* places the system label file in the root directory of the DVD.

This command will work with DVD-R, DVD+R, DVD-RW, and DVD+RW media.

To create a compressed DVD, use the mkzftree command to create a compressed copy of the origin directories:

# mkdir /tmp/zftree

# mkzftree /home /tmp/zftree/home

# mkzftree /etc /tmp/zftree/etc

You will need sufficient disk space to hold the compressed image before it is written to the optical disc.

Then use the -z option to growisofs :

# growisofs -Z /dev/dvd -RJz /tmp/zftree /system-*

Putting this all together into a script, and mailing the results to the email alias backup-alert , we get this:

#!/bin/bash

#

# backup-dvd :: backup selected directories to a compressed DVD

#

# List of the directories to be backed up

DIRLIST

= "

/etc /home "

# Create timestamp file

(

rm -f /system-*

touch /system-$(hostname)

# Make directory for compressed backup tree

rm -rf /tmp/zftree 2>/dev/null

mkdir /tmp/zftree

RESULT=0

for DIR in $DIRLIST

do

mkzftree $DIR /tmp/zftree${DIR}

RESULT=$(( $? + $RESULT ))

done

if [ "$RESULT" -eq 0 ]

then

# Burn the DVD

growisofs -Z /dev/dvd -RJz /tmp/zftree /system-*

# Eject the disc

eject

else

echo "Skipping burn: file compression failed."

fi

# Delete the zftree

rm -rf /tmp/zftree 2>/dev/null

) 2>&1|mail -s "Backup Log $(hostname)" backup-alert

Edit the DIRLIST line so that it contains a list of the directories to be backed up, separated by spaces.

Save this file as /usr/local/bin/backup-dvd and then make it executable:

# chmod u+rx /usr/local/bin/backup-dvd

And be sure to create an email alias for the backup-alert user in the file /etc/aliases :

backup-alert: chris frank

To produce a backup, execute this script:

# backup-dvd

But it's a better idea to configure the system to run this script automatically every night (see Lab 6.4, "Scheduling Tasks ").

To back up directories to tape, use the tape archiver ( tar ):

# tar -cf /dev/st0 /system-* /etc /home

tar: Removing leading \Q/' from member names

tar: Removing leading \Q/' from hard link targets

In this command, /dev/st0 is the first tape drive, and /etc and /home are the directories being backed up.

To perform a compressed backup, add the z (for gzip compression) or j (for bzip2 compression) option:

# tar -czf /dev/st0 /system-* /etc /home

tar: Removing leading \Q/' from member names

tar: Removing leading \Q/' from hard link targets

Here is a script that will perform a tape backup:

#!/bin/bash

#

# backup-tape :: backup selected directories to a compressed tape

#

# List of the directories to be backed up

DIRLIST="

/etc /home "

# Create timestamp file

(

rm -f /system-*

touch /system-$(hostname)

# Produce the tape

tar -czf /dev/st0 /system-* $DIRLIST

# Eject the tape if possible

mt -f /dev/st0 eject

) 2>&1|mail -s "Backup Log $(hostname)" backup-alert

Save this script as /usr/local/bin/backup-tape .

Like the backup-dvd script, this script will send an email report to the email alias backup-alert . To include a list of files in the email report, add the -v option to the tar command:

tar -cz v f /dev/st0 /system-* $DIRLIST

To produce a backup tape, run the script from the command line:

# backup-tape

It's best to run this script automatically every night (see Lab 6.4, "Scheduling Tasks ").