From: Christoph Anton Mitterer <calestyo@scientia.net>
To: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>,
Hans van Kranenburg <Hans.van.Kranenburg@mendix.com>,
linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: dm-integrity + mdadm + btrfs = no journal?
Date: Wed, 30 Jan 2019 16:26:08 +0100 [thread overview]
Message-ID: <6ce96b57897acb62101dd213f8127ffeb981ee90.camel@scientia.net> (raw)
In-Reply-To: <5c11b6a4-de3d-2ba0-c5c6-65ea04cd0245@gmail.com>
On Wed, 2019-01-30 at 07:58 -0500, Austin S. Hemmelgarn wrote:
> Running dm-integrity without a journal is roughly equivalent to
> using
> the nobarrier mount option (the journal is used to provide the same
> guarantees that barriers do). IOW, don't do this unless you are
> willing
> to lose the whole volume.
That sounds a bit strange to me.
My understanding was that the idea of being able to disable the journal
of dm-integrity was just to avoid any double work, if equivalent
guarantees are already given by higher levels.
If btrfs is by itself already safe (by using barriers), then I'd have
expected that not transaction is committed, unless it got through all
lower layers... so either everything works well on the dm-integrity
base (and thus no journal is needed)... or it fails there... but then
btrfs would already safe by it's own means (barriers + CoW)?
Cheers,
Chris.
next prev parent reply other threads:[~2019-01-30 15:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-29 23:15 dm-integrity + mdadm + btrfs = no journal? Hans van Kranenburg
2019-01-30 1:02 ` Chris Murphy
2019-01-30 8:42 ` Roman Mamedov
2019-01-30 12:58 ` Austin S. Hemmelgarn
2019-01-30 15:26 ` Christoph Anton Mitterer [this message]
2019-01-30 16:00 ` Austin S. Hemmelgarn
2019-01-30 16:31 ` Christoph Anton Mitterer
2019-01-30 16:38 ` Hans van Kranenburg
2019-01-30 16:56 ` Hans van Kranenburg
-- strict thread matches above, loose matches on Subject: below --
2018-11-04 22:55 Hans van Kranenburg
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