According to Tony's info, it will take a very long time to create because it needs to convert first.
Like what Dominic said, not only wasting time but also wasting the compute node disk space in every creation.

Still suggest converting to RAW format first, only a long time to upload the Ceph for the first time.

<DHilsbos@performair.com> 於 2021年4月2日 週五 下午11:23寫道：
Tony;

In accordance with the second "Important" note listed here: https://docs.ceph.com/en/nautilus/rbd/rbd-openstack/, we use all RAW images.

Thank you,

Dominic L. Hilsbos, MBA
Director ? Information Technology
Perform Air International Inc.
DHilsbos@PerformAir.com
www.PerformAir.com


-----Original Message-----
From: Tony Liu [mailto:tonyliu0592@hotmail.com]
Sent: Thursday, April 1, 2021 5:19 PM
To: Dominic Hilsbos
Cc: openstack-discuss@lists.openstack.org; missile0407@gmail.com
Subject: Re: launch VM on volume vs. image

Hi Dominic,

What's your image format?


Thanks!
Tony
________________________________________
From: DHilsbos@performair.com <DHilsbos@performair.com>
Sent: April 1, 2021 10:47 AM
To: tonyliu0592@hotmail.com
Cc: openstack-discuss@lists.openstack.org; missile0407@gmail.com
Subject: RE: launch VM on volume vs. image

Tony / Eddie;

I think this is partially dependent on the version of OpenStack running.  In our Victoria cloud, a volume created from an image is also done as a snapshot by Ceph, and is completed in seconds.

Thank you,

Dominic L. Hilsbos, MBA
Director ? Information Technology
Perform Air International Inc.
DHilsbos@PerformAir.com
www.PerformAir.com

From: Eddie Yen [mailto:missile0407@gmail.com]
Sent: Wednesday, March 31, 2021 6:00 PM
To: Tony Liu
Cc: openstack-discuss@lists.openstack.org
Subject: Re: launch VM on volume vs. image

Hi Tony,

In Ceph layer, IME, launching VM on image is creating a snapshot from source image in Nova ephemeral pool.
If you check the RBD image created in Nova ephemeral pool, all images have their own parents from glance images.

For launching VM on volume, it will "copy" the image to volume pool first, resize to specified disk size, then connect and boot.
Because it's not create a snapshot from image, so it will take much longer.

Eddie.

Tony Liu <tonyliu0592@hotmail.com> 於 2021年4月1日 週四 上午8:09寫道：
Hi,

With Ceph as the backend storage, launching a VM on volume takes much
longer than launching on image. Why is that?
Could anyone elaborate the high level workflow for those two cases?


Thanks!
Tony