linux-ext4 - Re: State of dump utility

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Date:   Fri, 2 Oct 2020 13:15:33 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Lukas Czerner <lczerner@...hat.com>, linux-ext4@...r.kernel.org
Subject: Re: State of dump utility

On Tue, Sep 29, 2020 at 10:06:46PM -0400, Theodore Y. Ts'o wrote:
> One of the interesting questions is how reliable the dump utility
> really is; that's because it works by reading the metadata directly
> --- while the file system is mounted.  So it's quite possible for the
> metadata to be changing out from under the dump/restore process.
> Especially with metadata checksums, I suspect dump/restore is going
> much more unreliable in terms of the libext2fs returning checksum
> failures.

Before using a tool like dumpe2fs you'll need to do a fsfreeze,
and then everything should be fine.  Best would be to patch the
tool to issue the freeze/unfreeze ioctls itself.