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Date:   Tue, 15 Jun 2021 08:23:50 -0700
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Ralf =?iso-8859-1?Q?Gro=DF?= <ralf.gross+xfs@gmail.com>
Cc:     linux-xfs@vger.kernel.org
Subject: Re: copy / move reflink files to new filesystem / or whole fs
Message-ID: <20210615152350.GA158209@locust>
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On Tue, Jun 15, 2021 at 07:45:59AM +0200, Ralf Groß wrote:
> Hi,
> 
> is there any way to copy or move data between 2 xfs fs with reflinks
> on the same host, so that the data is not rehydrated (I guess cp
> --reflink will not be working)? If this is not possible, would it be
> able to clone the existing fs to a new one and then continue to use
> both?
>
> Background: I've backup data on a 350 TB reflink xfs fs, now a second
> fs will be added to the server and parts of existing data should be
> moved to it. If it's possible to clone the whole fs I could delete
> parts of it afterwards, but copying/moving single directories would be
> easier.

Reflinking (aka data block sharing) can only be performed between files
within a single filesystem.  You could use xfs_copy to clone the fs
which would be faster than dd, though not as fast as targeted copying of
parts of the directory tree as needed.

--D

> 
> Ralf