[openstack-dev] [cinder] Propose to add copying the reference images when creating a volume
Sheng Bo Hou
sbhou at cn.ibm.com
Mon Jul 1 10:35:03 UTC 2013
First, thanks for answering.
I was trying to find the way to prepare the bootable volume.
Take the default image downloaded by devstack, there are three images:
cirros-0.3.0-x86_64-uec, cirros-0.3.0-x86_64-uec-kernel and
cirros-0.3.0-x86_64-uec-kernel is referred as the kernel image and
cirros-0.3.0-x86_64-uec-ramdisk is referred as the ramdisk image.
Issue: If only the image(cirros-0.3.0-x86_64-uec) is copied to the volume
when creating a volume) from an image, this volume is unable to boot an
instance without the references to the kernel and the ramdisk images. The
current cinder only copies the image cirros-0.3.0-x86_64-uec to one
targeted volume(Vol-1), which is marked as bootable but unable to do a
successful boot with the current nova code, even if image-id is removed in
Possible solutions: There are two ways in my mind to resolve it. One is we
just need the code change in Nova to let it find the reference images for
the bootable volume(Vol-1) and there is no need to change anything in
cinder, since the kernel and ramdisk id are saved in the
volume_glance_metadata, where the references point to the images(kernel
and ramdisk) for the volume(Vol-1).
The other is that if we need multiple images to boot an instance, we need
a new way to create the bootable volume. For example, we can create three
separate volumes for three of the images and set the new references in
volume_glance_metadata with the kernel_volume_id and ramdisk_volume_id.
The benefit of this approach is that the volume can live independent of
the existence of the original images. Even the images get lost
accidentally, the volumes are still sufficient to boot an instance,
because all the information have been copied to Cinder part.
I am trying to looking for the "another way to prepare your bootable
volume" as you mentioned and asking for the suggestions.
And I think the second approach could be one way. Do you think it is a
Vincent Hou (侯胜博)
Staff Software Engineer, Open Standards and Open Source Team, Emerging
Technology Institute, IBM China Software Development Lab
Tel: 86-10-82450778 Fax: 86-10-82453660
Notes ID: Sheng Bo Hou/China/IBM at IBMCN E-mail: sbhou at cn.ibm.com
Address:3F Ring, Building 28 Zhongguancun Software Park, 8 Dongbeiwang
West Road, Haidian District, Beijing, P.R.C.100193
Mate Lakat <mate.lakat at citrix.com>
Please respond to
OpenStack Development Mailing List <openstack-dev at lists.openstack.org>
OpenStack Development Mailing List <openstack-dev at lists.openstack.org>,
jsbryant at us.ibm.com, "Duncan Thomas <duncan.thomas at gmail.com> John
Griffith" <duncan.thomas at gmail.comduncan.thomas>
Re: [openstack-dev] [cinder] Propose to add copying the reference images
when creating a volume
I just proposed a patch for the boot_from_volume_exercise.sh to get rid
of --image. To be honest, I did not look at the various execution paths.
My initial thought is that boot from volume means you boot from volume.
If you only have a kernel + ramdisk image, I simply assumed that you
can't do it.
I would not do any magic. Boot from volume should boot from volume. If
you only have 3 part images, you need to find another way to prepare
your bootable volume.
btw, here is my change:
On Mon, Jul 01, 2013 at 01:25:23AM -0400, Sheng Bo Hou wrote:
> Hi Cinder folks,
> I am currently fixing the bugs related to booting the instance from the
> volume. I found there are bugs both in Nova and
> Cinder: https://bugs.launchpad.net/cinder/+bug/1159824
> Nova: https://bugs.launchpad.net/nova/+bug/1191069
> For the volumes created from the image, I propose to copy the reference
> image during the creation of
> the main image. For example, an image may refer to a kernel image and a
> ramdisk image. When we create a volume
> from this image, we only copied this one to the volume. The kernel and
> ramdisk images are still in glance, and
> the volume still refers to the kernel and ramdisk images.
> I think if an image has other reference images, the reference images
> need to be copied to the volumes(kernel volume and ramdisk volume),
> and then set the volume referring to the kernel volume and the ramdisk
> volume. This feature will make booting from
> a volume completely independent of the existence of the glance image.
> Do you think we can firstly add this feature to cinder? Do folks have
> comments on it?
> Best wishes,
> Vincent Hou (侯胜博)
> Staff Software Engineer, Open Standards and Open Source Team, Emerging
> Technology Institute, IBM China Software Development Lab
> Tel: 86-10-82450778 Fax: 86-10-82453660
> Notes ID: Sheng Bo Hou/China/IBM at IBMCN E-mail: sbhou at cn.ibm.com
> Address:3F Ring, Building 28 Zhongguancun Software Park, 8 Dongbeiwang
> West Road, Haidian District, Beijing, P.R.C.100193
> 地址:北京市海淀区东北旺西路8号中关村软件园28号楼环宇大厦3层 邮编：100193
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
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