Dump questions

Polytropon freebsd at edvax.de
Sun Feb 21 10:04:16 UTC 2010

On Sun, 21 Feb 2010 11:42:50 +0800, Aiza <aiza21 at comclark.com> wrote:
> 1. Using the -L flag to create a snapshot of the
> live running file system.
> Does this mean that a complete copy of the file
> system is written to .snap directory?

No. The snapshot, quite incorrectly explained, is a saved
delta between the file system on disk at a given state, to
fixate further modifications (that are not included in the
dump, of course).

> Is this the limiting factor that forces a user
> to use (single user mode) for running dump?

Using SUM is for a feeling of comfort only. You can save
the time needed for creating the snapshot by entering
SUM - and, what's essential - unmount the partitions.
This makes sure the underlying file systems aren't

> 2. What is the worse that will happen if dump is
> run on live file system with out the -L flag?

The dump could not be readable, which would imply that
your backup is useless.

> Can dump recognize this situation and issue
> an error message?

The dump program does what you tell it to do. It does
not bother you with questions that you should have asked
yourself already. :-)

> 3. Can dump be told to only dump a particular
> directory tree? IE /var/log  or /usr/port?

No. THe dump program operates on file systems. It does
not have a concept of files and directories per se.

If you plan to work with individual files and directories
rather than partitions (file systems), check out tools
like cpdup, rsync and the like.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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