Re: [gentoo-user] Ghosting a Ext3 partition

[Rasmus Andersen <rasmus@avlebavle.dk>]

On Sun, Mar 02, 2008 at 05:51:06PM +1300, Mark Kirkwood wrote:
> I wrote:
>>
>>
>> If you want to back the system up while it is running (in particular /), 
>> then you need to use a tool that understands how to create a backup image 
>> that is valid (i.e will boot) - something like xfsdump, *dumpe2fs* etc or 
>> smart tar/dump based tools like Amanda.
> Hmm - dunno what I was thinking there -  'dumpe2fs' is completely wrong, 
> should have written 'dump', sorry!

If you do backup live filesystems/data then dump is on par with dd; both
read from the underlying device and might bypass the kernel's page cache.
Ie., there might be unwritten data cached thats not on disk yet.
Tar/rdiff-backup/etc reads through the pagecache and avoids this problem.

The dump people talk a bit about this themselves on

   http://dump.sourceforge.net/isdumpdeprecated.html

Note I dont want to dis dump, backing up live filesystems is just tricky
(depending on your consistency requirements :) and dump adds another
level to that.

Cheers,
  Rasmus
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