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Message-ID: <64c763540511142345g4ca0b184y28962dae494f22b4@mail.gmail.com>
Date: Tue, 15 Nov 2005 13:15:54 +0530
From: Block Device <blockdevice@gmail.com>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: A standard snapshot notification framework in Linux ?
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Hi,

   does the linux kernel provide a mechanism whereby applications can
register themselves
to be notified when a snapshot is being taken of the volume they might
be writing to.

   If there is no such framework then how do backup applications
guarantee ( application level ) consistency. I have seen freeze_bdev
and friends which work for file systems and how the device mapper uses
them. But when it comes to application level consistency, a mechanism
is required to give the application a chance to flush &  quiesce its
writes so that the backup taken will be consistent for the application
also. Windows has the VSS ( Volume Shadow Service ) which provides an
elaborate framework for this. Is anyone working on something similar
for Linux and if not why is it not such a worthwhile idea ?

Regards
BD
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