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Date:   Sun, 11 Apr 2021 22:43:28 +0200
From:   Adam Borowski <kilobyte@angband.pl>
To:     Roman Mamedov <rm@romanrm.net>
Cc:     Chris Murphy <lists@colorremedies.com>,
        Paul Leiber <paul@onlineschubla.de>,
        "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: Parent transid verify failed (and more): BTRFS for data storage
 in Xen VM setup
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On Sun, Apr 11, 2021 at 12:10:34PM +0500, Roman Mamedov wrote:
> On Sat, 10 Apr 2021 17:06:22 -0600
> Chris Murphy <lists@colorremedies.com> wrote:
> 
> > Right. The block device (partition containing the Btrfs file system)
> > must be exclusively used by one kernel, host or guest. Dom0 or DomU.
> > Can't be both.
> > 
> > The only exception I'm aware of is virtiofs or virtio-9p, but I
> > haven't messed with that stuff yet.
> 
> If you want an FS that allows a block device to be mounted by multiple machines
> at the same time, there are a few:
> https://en.wikipedia.org/wiki/Clustered_file_system#Shared-disk_file_system

All of those use some kind of lock manager, though.
So in no case you just mount the same device twice.

-- 
⢀⣴⠾⠻⢶⣦⠀ .--[ Makefile ]
⣾⠁⢠⠒⠀⣿⡁ # beware of races
⢿⡄⠘⠷⠚⠋⠀ all: pillage burn
⠈⠳⣄⠀⠀⠀⠀ `----