[openstack-dev] [Nova] Deprecating localfs?

Daniel P. Berrange berrange at redhat.com
Tue Sep 23 10:58:09 UTC 2014


On Tue, Sep 23, 2014 at 02:27:52PM +0400, Roman Bogorodskiy wrote:
>   Michael Still wrote:
> 
> > Hi.
> > 
> > I know we've been talking about deprecating nova.virt.disk.vfs.localfs
> > for a long time, in favour of wanting people to use libguestfs
> > instead. However, I can't immediately find any written documentation
> > for when we said we'd do that thing.
> > 
> > Additionally, this came to my attention because Ubuntu 14.04 is
> > apparently shipping a libguestfs old enough to cause us to emit the
> > "falling back to localfs" warning, so I think we need Ubuntu to catch
> > up before we can do this thing.
> > 
> > So -- how about we remove localfs early in Kilo to give Canonical a
> > release to update libguestfs?
> > 
> > Thoughts appreciated,
> > Michael
> 
> If at some point we'd start moving into getting FreeBSD supported as a
> host OS for OpenStack, then it would make sense to keep localfs for that
> configuration.
> 
> libguestfs doesn't work on FreeBSD yet. On the other hand, localfs
> code in Nova doesn't look like it'd be hard to port.

Yep, that's a good point and in fact applies to Linux too when considering
the non-KVM/QEMU drivers libvirt supports. eg if your host does not have
virtualization and you're using LXC for container virt, then we need to 
have localfs still be present. Likewise if running Xen.

So we definitely cannot delete or even deprecate it unconditionally. We
simply want to make sure localfs isn't used when Nova is configured to
run QEMU/KVM via libvirt.

So if we take the config option approach I suggested, then we'd set a
default value for the vfs_impl parameter according to which libvirt
driver you have enabled.

Regards,
Daniel
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