How does /etc/fstab backup data?

Question

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

I want to know what it backup? The whole filesystem?
where is the backup file?
When does it work? On every boot?
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.

Thank you, but I've read that before, it helped me to ask these questions. @Pilot6 — Mohammad Kholghi, Aug 09 '19 at 11:03
So people these days backup their data just using copy/paste? @Pilot6 — Mohammad Kholghi, Aug 09 '19 at 11:06
Forget about dumping 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 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

score 1 · Answer 1 · answered Aug 09 '19 at 11:03

1

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.

answered Aug 09 '19 at 11:03

Soren A

6,799

How does dump command work? I have never heard of it. – Mohammad Kholghi Aug 09 '19 at 11:04
4

It doesn't work, because dump is not installed in Ubuntu. – Pilot6 Aug 09 '19 at 11:05
1

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

How does /etc/fstab backup data?

1 Answers1