There are four parts to a Cedar Backup run: collect, stage, store and purge. The usual way of setting off these steps is through a set of cron jobs. Although you won't create your cron jobs just yet, you should decide now when you will run your backup so you are prepared for later.

Backing up large directories and creating ISO filesystem images can be intensive operations, and could slow your computer down significantly. Choose a backup time that will not interfere with normal use of your computer. Usually, you will want the backup to occur every day, but it is possible to configure cron to execute the backup only one day per week, three days per week, etc.

Cedar Backup relies on email for problem notification. This notification works through the magic of cron. Cron will email any output from each job it executes to the user associated with the job. Since by default Cedar Backup only writes output to the terminal if errors occur, this ensures that notification emails will only be sent out if errors occur.

In order to receive problem notifications, you must make sure that email works for the user which is running the Cedar Backup cron jobs (typically root). Refer to your distribution's documentation for information on how to configure email on your system. Note that you may prefer to configure root's email to forward to some other user, so you do not need to check the root user's mail in order to see Cedar Backup errors.

Before using Cedar Backup, your writer device must be properly configured. If you have configured your CD/DVD writer hardware to work through the normal filesystem device path, then you just need to know the path to the device on disk (something like /dev/cdrw). Cedar Backup will use the this device path both when talking to a command like cdrecord and when doing filesystem operations like running media validation.

Your other option is to configure your CD writer hardware like a SCSI device (either because it is a SCSI device or because you are using some sort of interface that makes it look like one). In this case, Cedar Backup will use the SCSI id when talking to cdrecord and the device path when running filesystem operations.

See the section called “Configuring your Writer Device” for more information on writer devices and how they are configured.

Choose a user to be used for backups. Some platforms may come with a “ready made” backup user. For other platforms, you may have to create a user yourself. You may choose any id you like, but a descriptive name such as backup or cback is a good choice. See your distribution's documentation for information on how to add a user.

Cedar Backup requires a backup directory tree on disk. This directory tree must be roughly three times as big as the amount of data that will be backed up on a nightly basis, to allow for the data to be collected, staged, and then placed into an ISO filesystem image on disk. (This is one disadvantage to using Cedar Backup in single-machine pools, but in this day of really large hard drives, it might not be an issue.) Note that if you elect not to purge the staging directory every night, you will need even more space.

You should create a collect directory, a staging directory and a working (temporary) directory. One recommended layout is this:

/opt/
     backup/
            collect/
            stage/
            tmp/
         

If you will be backing up sensitive information (i.e. password files), it is recommended that these directories be owned by the backup user (whatever you named it), with permissions 700.

Following the instructions in the section called “Configuration File Format” (above) create a configuration file for your machine. Since you are working with a pool of one, you must configure all four action-specific sections: collect, stage, store and purge.

The usual location for the Cedar Backup config file is /etc/cback.conf. If you change the location, make sure you edit your cronjobs (below) to point the cback script at the correct config file (using the --config option).

Use the command cback validate to validate your configuration file. This command checks that the configuration file can be found and parsed, and also checks for typical configuration problems, such as invalid CD/DVD device entries.

Note: the most common cause of configuration problems is in not closing XML tags properly. Any XML tag that is “opened” must be “closed” appropriately.

Place a valid CD/DVD disc in your drive, and then use the command cback --full all. You should execute this command as root. If the command completes with no output, then the backup was run successfully.

Just to be sure that everything worked properly, check the logfile (/var/log/cback.log) for errors and also mount the CD/DVD disc to be sure it can be read.

If Cedar Backup ever completes “normally” but the disc that is created is not usable, please report this as a bug. ^[20] To be safe, always enable the consistency check option in the store configuration section.

Since Cedar Backup should be run as root, one way to configure the cron job is to add a line like this to your /etc/crontab file:

30 00 * * * root  cback all
         

Or, you can create an executable script containing just these lines and place that file in the /etc/cron.daily directory:

#/bin/sh
cback all
         

You should consider adding the --output or -O switch to your cback command-line in cron. This will result in larger logs, but could help diagnose problems when commands like cdrecord or mkisofs fail mysteriously.