The ephemeral disk and the swap disk locally in the nova-compute node when image_type=rbd

Bug #1420274 reported by Yogev Rabl on 2015-02-10
32
This bug affects 7 people
Affects Status Importance Assigned to Milestone
OpenStack Compute (nova)
Low
Unassigned

Bug Description

Description of problem:
The Nova saves templates of the ephemeral and swap disks locally in the compute nodes, in /var/lib/nova/instances/_base directory

Version-Release number of selected component (if applicable):
openstack-nova-compute-2014.2.1-14.el7ost.noarch
openstack-nova-api-2014.2.1-14.el7ost.noarch

How reproducible:
100%

Steps to Reproduce:
1. Set Nova to work with Ceph as the back end of the compute nodes
2. Create a flavor that has ephemeral and swap disks
3. Launch an instance

Actual results:
Templates of the ephemeral and swap disks are been saved in the /var/lib/nova/instances/_base directory

Expected results:
These disks should be saved in the Ceph storage

How/what did you do in #1? example did you set images_type to 'rbd' in nova.conf? http://docs.openstack.org/trunk/config-reference/content/list-of-compute-config-options.html

Changed in nova:
status: New → Incomplete
Yogev Rabl (yrabl) wrote :

I have set the images_type to rbd, according to the manual in the formal Ceph documentation: http://docs.ceph.com/docs/master/rbd/rbd-openstack/

Changed in nova:
status: Incomplete → New
Sean Dague (sdague) wrote :

Marking as low as it is one storage back end. Operators were talking about this issue at the Philly midcycle, and I think this is mostly a ceph specific optimization that is needed here.

Changed in nova:
status: New → Confirmed
importance: Undecided → Low
tags: added: ceph
Michael Still (mikal) wrote :

I agree with Sean -- the image cache logic has no knowledge of the storage backends as best as I recall, it just makes things in _base and then moves them to whatever instance storage is configured. It would be interesting to get a feel for if operators thought this is a "big deal", or just a minor annoyance.

Eric Kolb (ekolb) wrote :

Yes, this annoying from an operators perspective. From what we experience the ephemeral disk gets created in /var/lib/nova/instances/_base/ first and then a "rbd import" is performed which can take significant time given large ephemeral disk definitions.

Changed in nova:
assignee: nobody → lyanchih (lyanchih)
Changed in nova:
assignee: Chung Chih, Hung (lyanchih) → nobody
Sean Dague (sdague) wrote :

Automatically discovered version juno in description. If this is incorrect, please update the description to include 'nova version: ...'

tags: added: openstack-version.juno
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