Image storage backend¶

Parameter	`features:nova:images:backend`
Usage	Defines the type of storage for Nova to use on the compute hosts for the images that back up the instances. The list of supported options include: `local` ^Deprecated Option is deprecated and replaced by `qcow2`. `qcow2` The local storage is used. The backend disk image format is `qcow2`. The pros include faster operation, failure domain independency from the external storage. The cons include local space consumption and less performant and robust live migration with block migration. `raw` ^{Available since 24.2} The local storage is used. The backend disk image format is `raw`. Raw images are simple binary dumps of disk data, including empty space, resulting in larger file sizes. They provide superior performance because they do not incur overhead from features such as compression or copy-on-write, which are present in the `qcow2` disk images. `ceph` Instance images are stored in a Ceph pool shared across all Nova hypervisors. The pros include faster image start, faster and more robust live migration. The cons include considerably slower IO performance, workload operations direct dependency on Ceph cluster availability and performance. `lvm` ^TechPreview Instance images and ephemeral images are stored on a local Logical Volume. If specified, `features:nova:images:lvm:volume_group` must be set to an available LVM Volume Group, by default, `nova-vol`. For details, see Enable LVM ephemeral storage.

Parameter

features:nova:images:backend

Usage

Defines the type of storage for Nova to use on the compute hosts for the images that back up the instances.

The list of supported options include:

local ^Deprecated
Option is deprecated and replaced by qcow2.
qcow2
The local storage is used. The backend disk image format is qcow2. The pros include faster operation, failure domain independency from the external storage. The cons include local space consumption and less performant and robust live migration with block migration.
raw ^{Available since 24.2}
The local storage is used. The backend disk image format is raw. Raw images are simple binary dumps of disk data, including empty space, resulting in larger file sizes. They provide superior performance because they do not incur overhead from features such as compression or copy-on-write, which are present in the qcow2 disk images.
ceph
Instance images are stored in a Ceph pool shared across all Nova hypervisors. The pros include faster image start, faster and more robust live migration. The cons include considerably slower IO performance, workload operations direct dependency on Ceph cluster availability and performance.
lvm ^TechPreview
Instance images and ephemeral images are stored on a local Logical Volume. If specified, features:nova:images:lvm:volume_group must be set to an available LVM Volume Group, by default, nova-vol. For details, see Enable LVM ephemeral storage.