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

[Klaus Espenlaub]

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.

Klaus

> Thank you for reading
>
> Regards
>
> Paul