In "/etc/fstab" the entries are like this

tmpfs                   /dev/shm                tmpfs   defaults        0 0

The fifth field (0) is used by dump (a backup utility) to decide if a filesystem should be backed up.But if I provide it as "1", then where this backup will be created?

Please accept apologies if I am asking something stupid...


migrated from serverfault.com Mar 10 '15 at 9:59

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That is not working automatically. If you have set 1 to the 5th field in /etc/fstab that means nothing yet. First the utillity dump must exist on the system (nowadays it's most probably not installed). Second, dump must be called manually or at least via cron.

Earlier, dump was used to make backups on tape drives. An advantage of dump was the fact that it operated below the filesystem, so when backuping the access time of files and folders was not changed. dump can also print the backup to stdout. So it was also used to pipe the output trough an ssh connection to a backup server.

But, take care when backuping with dump. dump can safely be used against unmounted and read-only filesystems. On mounted filesystem that are not idle, I wouldn't recommend dump.


The fifth field is a flag that indicates if this file has to be included during a backup operation using dump.

Suppose you use this command:

dump -0uf /media/usb1/my_backup /home/newuser/documents

It will create a level 0 dump file called my_backup on /media/usb1 with the contents of /home/newuser/documents that have the flag.

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