Re: Debian tool for creating drive images from mounted devices?

From	Jochen Spieker <ml@well-adjusted.de>
Newsgroups	linux.debian.user
Subject	Re: Debian tool for creating drive images from mounted devices?
Date	2026-05-07 15:10 +0200
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tomas@tuxteam.de:
> 
> - You have the structural consistency of the file system itself
>   (directory structure, partial writes to files, superblock, etc).
>   LVM and other snapshotters help you with that.

I was always under the impression that an LVM snapshot is not better
than an unclean filesystem, like for example after a power loss. But
this 20 year old document proved me wrong:

https://tldp.org/HOWTO/LVM-HOWTO/snapshotintro.html

| This facility does require that the snapshot be made at a time when
| the data on the logical volume is in a consistent state - the VFS-lock
| patch for LVM1 makes sure that some filesystems do this automatically
| when a snapshot is created, and many of the filesystems in the 2.6
| kernel do this automatically when a snapshot is created without
| patching. 

I did not current information on this explicitly, but apparently
nowadays you can expect that "many filesystems" actually support being
snapshotted by LVM and make sure that the state on disk is clean when an
LVM snapshot is created.

> - Then you have the consistency of the data in the file system itself
>   (imagine a backing file for a relational database, say PostgreSQL,
>   for example). For that, only the applications themselves can help
>   you, no amount of LVM or snapshotting will, because it knows nothing
>   about the applications's inner structures.

This is also true.

For home/office machines a simple file-based backup solution is usually
sufficent. For servers that might not be the case and you should rely on
application-specific backup tools.

I have never felt the urge to backup a partition layout or do a "whole
disk backup" in one step. I am using LVM on all of my machines for
flexibility (filesystem resizing) and convenience (disk migration
possibilities).

J.
-- 
My medicine shelf is my altar.
[Agree]   [Disagree]
                 <http://archive.slowlydownward.com/NODATA/data_enter2.html>

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Debian tool for creating drive images from mounted devices? Hans <hans.ullrich@mail.de> - 2026-05-07 10:50 +0200
  Re: Debian tool for creating drive images from mounted devices? Geert Stappers <stappers@stappers.nl> - 2026-05-07 11:00 +0200
    Re: Debian tool for creating drive images from mounted devices? Hans <hans.ullrich@mail.de> - 2026-05-07 11:40 +0200
  Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-07 12:40 +0200
    Re: Debian tool for creating drive images from mounted devices? Tim Woodall <debianuser@woodall.me.uk> - 2026-05-10 12:50 +0200
  Re: Debian tool for creating drive images from mounted devices? Joe <joe@jretrading.com> - 2026-05-07 12:40 +0200
    Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-07 12:50 +0200
      Re: Debian tool for creating drive images from mounted devices? Jochen Spieker <ml@well-adjusted.de> - 2026-05-07 15:10 +0200
        Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-07 15:30 +0200
          Re: Debian tool for creating drive images from mounted devices? Jochen Spieker <ml@well-adjusted.de> - 2026-05-07 16:10 +0200
        Re: Debian tool for creating drive images from mounted devices? Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-07 16:00 +0200
          Re: Debian tool for creating drive images from mounted devices? Jochen Spieker <ml@well-adjusted.de> - 2026-05-07 16:10 +0200
            Re: Debian tool for creating drive images from mounted devices? Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-07 18:00 +0200
              Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-07 19:00 +0200
                Re: Debian tool for creating drive images from mounted devices? Joe <joe@jretrading.com> - 2026-05-07 20:00 +0200
                Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-07 20:20 +0200
                Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-10 14:50 +0200
                Re: Debian tool for creating drive images from mounted devices? Arno Lehmann <al@its-lehmann.de> - 2026-05-11 14:30 +0200
                Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-11 15:00 +0200
                Re: Debian tool for creating drive images from mounted devices? Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-11 17:50 +0200
                Re: Debian tool for creating drive images from mounted devices? Arno Lehmann <al@its-lehmann.de> - 2026-05-11 18:30 +0200
                Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-11 18:40 +0200
                Re: Debian tool for creating drive images from mounted devices? Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-11 22:00 +0200
                Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-11 18:30 +0200
                Re: Debian tool for creating drive images from mounted devices? Andy Smith <andy@strugglers.net> - 2026-05-11 19:50 +0200
                Re: Debian tool for creating drive images from mounted devices? Arno Lehmann <al@its-lehmann.de> - 2026-05-11 22:00 +0200
                Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-12 08:00 +0200
                Re: Debian tool for creating drive images from mounted devices? Andy Smith <andy@strugglers.net> - 2026-05-12 13:40 +0200
                Re: Debian tool for creating drive images from mounted devices? Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-07 21:10 +0200
  Re: Debian tool for creating drive images from mounted devices? Arno Lehmann <al@its-lehmann.de> - 2026-05-07 13:10 +0200
    Re: Debian tool for creating drive images from mounted devices? Hans <hans.ullrich@mail.de> - 2026-05-07 13:40 +0200
    Re: Debian tool for creating drive images from mounted devices? Hans <hans.ullrich@mail.de> - 2026-05-07 13:40 +0200
      Re: Debian tool for creating drive images from mounted devices? Charles Curley <charlescurley@charlescurley.com> - 2026-05-07 15:50 +0200
        Re: Debian tool for creating drive images from mounted devices? <tomas@tuxteam.de> - 2026-05-07 16:20 +0200
        Re: Debian tool for creating drive images from mounted devices? "Roy J. Tellason, Sr." <roy@rtellason.com> - 2026-05-07 20:30 +0200
      Re: Debian tool for creating drive images from mounted devices? Andy Smith <andy@strugglers.net> - 2026-05-07 18:30 +0200

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