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Re: dd and xfs

To: Yannick Ribau <yannick.ribau@xxxxxxx>
Subject: Re: dd and xfs
From: Steve Lord <lord@xxxxxxx>
Date: 13 Nov 2001 10:58:52 -0600
Cc: linux-xfs <linux-xfs@xxxxxxxxxxx>
In-reply-to: <3BF15156.9050104@xxxxxxx>
References: <3BF145FE.2050003@xxxxxxx> <1005669205.19062.5.camel@xxxxxxxxxxxxxxxxxxxx> <3BF15156.9050104@xxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
On Tue, 2001-11-13 at 10:59, Yannick Ribau wrote:
> So it might work if I boot from a rescue CD with a kernel supporting 
> xfs, then do the dd command without mounting the partitions (using 
> /dev/hda...) ?

Yes, it would work in this case - you are just creating an identical
copy of the fs. But if this is an option, then so is xfsdump/restore
which would take up less space.

Steve

> 
> Yannick.
> 
> Steve Lord wrote:
> 
> > On Tue, 2001-11-13 at 10:10, Yannick Ribau wrote:
> > 
> >>hi all,
> >>
> >>is it possible to make a "dd conv=noerror /dev/hda2 /dev/hda3" to have a 
> >>complete backup of my root filesystem, then do a
> >>"dd conv=noerror /dev/hda3 /dev/hda2" to restore it, in case of a soft 
> >>filesystem problem ?
> >>
> >>(both partitions have the exact same size)
> >>
> > 
> > On a live filesystem this is not too smart an idea, the block cache and
> > the live filesystem are not totally coherent - in fact depending on the
> > kernel version they can be totally incoherent (changes to one are
> > invisible in the other).
> > 
> > You at least need to do a remount readonly to make the disk
> > image stable - and this will fail if a file is open for writing
> > 
> > Steve
> > 
> > 
> > 
> >>Yannick.
> 
> 
> 
-- 

Steve Lord                                      voice: +1-651-683-3511
Principal Engineer, Filesystem Software         email: lord@xxxxxxx


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