openstack/nova
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Adapt the admin guide to describe the direct RBD export

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This documents how to set up nova and glance so the feature
for direct download from Ceph can be used.

Change-Id: I07509c67c65e988fe5149b625007e90e68488cfd
This commit is contained in:
Jiří Suchomel 2020-05-15 12:20:03 +02:00 committed by Lee Yarwood
parent c57d52e197
commit a33f455ec7
1 changed files with 30 additions and 0 deletions
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doc/source/admin/configuration/hypervisor-kvm.rst
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@ -260,6 +260,36 @@ Local `LVM volumes
used. Set the :oslo.config:option:`libvirt.images_volume_group` configuration
option to the name of the LVM group you have created.
Direct download of images from Ceph
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When the Glance image service is set up with the Ceph backend and Nova is using
a local ephemeral store (``[libvirt]/images_type!=rbd``), it is possible to
configure Nova to download images directly into the local compute image cache.
With the following configuration, images are downloaded using the RBD export
command instead of using the Glance HTTP API. In some situations, especially
for very large images, this could be substantially faster and can improve the
boot times of instances.
On the Glance API node in ``glance-api.conf``:
.. code-block:: ini
[DEFAULT]
show_image_direct_url=true
On the Nova compute node in nova.conf:
.. code-block:: ini
[glance]
enable_rbd_download=true
rbd_user=glance
rbd_pool=images
rbd_ceph_conf=/etc/ceph/ceph.conf
rbd_connect_timeout=5
Specify the CPU model of KVM guests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~