[Openstack-operators] [Glance] [Nova] Multiple backends / Qcow Derived Images

Kris G. Lindgren klindgren at godaddy.com
Wed Jan 4 22:06:46 UTC 2017

We used raw backed qcows.  We even have/had an ansible playbook that would pre-stage the raw files on compute nodes.

This should be controlled by the: force_raw_images= True paramater (which also happens to be the default).  I don’t think its possible to do this via ephemeral volumes.

Re: your image placement there is schedulure options that cover image/falvor metadata and dedicating hosts to those specific images/flavors. http://docs.openstack.org/kilo/config-reference/content/section_compute-scheduler.html - Look for Images Properties filter and the Compute Capabilities Filter.  You may need to extend the image property filter to inculde random key matching https://github.com/openstack/nova/blob/master/nova/scheduler/filters/image_props_filter.py

Kris Lindgren
Senior Linux Systems Engineer

From: Adam Lawson <alawson at aqorn.com>
Date: Wednesday, January 4, 2017 at 2:48 PM
To: "openstack-operators at lists.openstack.org" <openstack-operators at lists.openstack.org>
Subject: Re: [Openstack-operators] [Glance] [Nova] Multiple backends / Qcow Derived Images

Just a friendly bump. To clarify, the ideas being tossed around are to host QCOW images on each Compute node so the provisioning is faster (i.e. less dependency on network connectivity to a shared back-end). I need to know if this is possible or not. So far, I've seen nothing that suggests that it is but i want to confirm that.

Also, derived images is a QCOW thing[1], I'm wondering if creating these dynamically is supported by Nova and/or Glance.

[1] http://nairobi-embedded.org/manipulating_disk_images_with_qemu-img.html#creating-derived-images


Adam Lawson

Principal Architect, CEO
Office: +1-916-794-5706

On Tue, Jan 3, 2017 at 5:01 PM, Adam Lawson <alawson at aqorn.com<mailto:alawson at aqorn.com>> wrote:
Greetings fellow Stackers!

Question re GlanceNova: Does Glance and/or Nova support attaching volumes built with derived images (created from a master registered with Glance (ref qcow))?

Glance-only question: Can Glance be configured to place images on separate hosts (i.e. imageX on ComputeX and imageY on ComputeY)?


Adam Lawson

Principal Architect, CEO
Office: +1-916-794-5706<tel:(916)%20794-5706>

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