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I was reading about /etc/fstab file, and found out that this file can dump data, and when searched for it, I understood that dump means backup.

# <file system>                 <dir>       <type>    <options>     <dump> <pass>
UUID=6a454a-bfd1-38989910eccd    /           ext4      defaults       1      1

  1. I want to know what it backup? The whole filesystem?

  2. where is the backup file?

  3. When does it work? On every boot?

  4. Does it need an external program called dump?

Edit: My question is not about the backup methods. I just want to know the story behind this dump column of the fstab file.

Mohammad Kholghi
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    https://superuser.com/a/247527/475611 – Pilot6 Aug 09 '19 at 10:59
  • Thank you, but I've read that before, it helped me to ask these questions. @Pilot6 – Mohammad Kholghi Aug 09 '19 at 11:03
  • It is not used any more. – Pilot6 Aug 09 '19 at 11:04
  • So people these days backup their data just using copy/paste? @Pilot6 – Mohammad Kholghi Aug 09 '19 at 11:06
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    There is a ton of backup methods, but this one is obsolete, – Pilot6 Aug 09 '19 at 11:10
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    Possible duplicate of [Comparison of backup tools](https://askubuntu.com/questions/2596/comparison-of-backup-tools) – Fabby Aug 10 '19 at 19:06
  • Forget about `dump`ing your file systems to tape: that is just *very ancient* technology (possible but not advised as a backup system any more). Have a look at the duplicate instead. – Fabby Aug 10 '19 at 19:09
  • Thank you very much, but my question is not about the "backup tools". I just wanted to know "the history of this column in `fstab`" and "How did it work in past?" . @Fabby – Mohammad Kholghi Aug 11 '19 at 08:05
  • [Reading the manual](https://linux.die.net/man/8/dump) is the best answer then as no one uses it any more. You'd have to find a greybeard that was a SysAdmin 30 years ago... **;-)** (I was one 20 years ago and we used `rsync` already back then...) – Fabby Aug 11 '19 at 08:26

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From man fstab:

   The  fifth  field,  (fs_freq),  is  used  for  these filesystems by the
   dump(8) command to determine which filesystems need to be  dumped.   If
   the  fifth  field  is not present, a value of zero is returned and dump
   will assume that the filesystem does not need to be dumped.

Nothing is dumped/backedup automatically.

Soren A
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  • How does `dump` command work? I have never heard of it. – Mohammad Kholghi Aug 09 '19 at 11:04
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    It doesn't work, because dump is not installed in Ubuntu. – Pilot6 Aug 09 '19 at 11:05
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    Any backup application could look at that fstab field to manage backup frequency or they can have another way to keep track of that. The format of /etc/fstab goes way back to the last century, and may have become redundant by now. – Soren A Aug 09 '19 at 11:11
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    https://linux.die.net/man/8/dump – Byte Commander Aug 09 '19 at 11:12
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    It's taken me ages to understand this. I finally realise that the "dump" value is used only when you use `dump -w` or `dump -W`. Even then, `dump` uses this only to display information about the dumps (backups) and not to do anything about it. Please correct me if I've misunderstood! (In any case, I rather suspect that the more modern backup systems `rsync`, `rdiff-backup` and `rclone` would be better substitutes.) – Paddy Landau Jan 17 '21 at 17:54