[vbox-dev] Do guest VMs communicate with external file systems through the host

Paul Paulsrsmith at live.co.uk
Mon Oct 10 15:50:26 UTC 2016

yes the concern is with the shared folder which is where the Shared SAN storage is mounted on the host. If the Windows VM writes to a file at the same time as one of the Redhat Nodes then there needs to be file locking or else data corruption will occur. This is already set up between the Redhat Nodes.

I think it is working through the host, because I believe Windows natively can't read GFS2 file systems... and I can see the shared files in Windows fine. But I could be wrong


From: vbox-dev-bounces at virtualbox.org <vbox-dev-bounces at virtualbox.org> on behalf of Klaus Espenlaub <klaus.espenlaub at oracle.com>
Sent: 10 October 2016 13:53
To: vbox-dev at virtualbox.org
Subject: Re: [vbox-dev] Do guest VMs communicate with external file systems through the host

Hi Paul,

On 10.10.2016 15:06, Paul wrote:
> Hi,
> I have a guest Windows VM under Redhat and the host is clustered with 2
> other Redhat nodes. All three nodes can see a GFS2 SAN SCSI storage device.
> The GFS2 file system is mounted on a folder on the 3 RH nodes and is
> also set as a shared folder in Virtualbox so all 3+1 machines can now
> see the SAN storage.
> So my question is about file locking. Does the Windows VM talk to the
> SAN file system through the host kernel, if so then I believe the
> clustered file locking should work fine, if not then it definitely won't.

Is your question specific to shared folders?

Then the answer is that VirtualBox on Linux doesn't rely on file locking
(as discretionary locking is a notoriously unreliable thing, and
mandatory locking is too unusual). It simply performs the file operations.


> Thank you for reading
> Regards
> Paul
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