[Openstack-operators] Experience with Cinder volumes as root disks?

Sean McGinnis sean.mcginnis at gmx.com
Tue Aug 1 15:55:15 UTC 2017

One other thing to think about - I think at least starting with the Mitaka
release, we added a feature called image volume cache. So if you create a
boot volume, the first time you do so it takes some time as the image is
pulled down and written to the backend volume.

With image volume cache enabled, that still happens on the first volume
creation of the image. But then any subsequent volume creations on that
backend for that image will be much, much faster.

This is something that needs to be configured. Details can be found here:



On Tue, Aug 01, 2017 at 10:47:26AM -0500, Sean McGinnis wrote:
> On Tue, Aug 01, 2017 at 11:14:03AM -0400, John Petrini wrote:
> > 
> > On the plus side for ephemeral storage; resizing the root disk of images
> > works better. As long as your image is configured properly it's just a
> > matter of initiating a resize and letting the instance reboot to grow the
> > root disk. When using volumes as your root disk you instead have to
> > shutdown the instance, grow the volume and boot.
> > 
> Some sort of good news there. Starting with the Pike release, you will now
> be able to extend an attached volume. As long as both Cinder and Nova are
> at Pike or later, this should now be allowed.
> Sean
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