openstack/ironic
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Merge "Add documentation covering storage multi-attach"

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Zuul 2018-01-15 22:47:38 +00:00 committed by Gerrit Code Review
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doc/source/admin/boot-from-volume.rst
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@ -68,3 +68,50 @@ that is unique to your SAN. For example, to create a volume connector for iSCSI:
openstack --os-baremetal-api-version 1.33 baremetal volume connector create \
--node $NODE_UUID --type iqn --connector-id iqn.2017-08.org.openstack.$NODE_UUID
Advanced Topics
===============
Use without the Compute Service
-------------------------------
As discussed in other sections, the Bare Metal service has a concept of a
`connector` that is used to represent an interface that is intended to
be utilized to attach the remote volume.
In addition to the connectors, we have a concept of a `target` that can be
defined via the API. While a user of this feature through the Compute
service would automatically have a new target record created for them,
it is not explicitly required, and can be performed manually.
A target record can be created using a command similar to the example below::
openstack --os-baremetal-api-version 1.33 baremetal volume target create \
--node $NODE_UUID --type iscsi --boot-index 0 --volume $VOLUME_UUID
.. Note:: A ``boot-index`` value of ``0`` represents the boot volume for a
node. As the ``boot-index`` is per-node in sequential order,
only one boot volume is permitted for each node.
Cinder Multi-attach
-------------------
Volume multi-attach is a function that is commonly performed in computing
clusters where dedicated storage subsystems are utilized. For some time now,
the Block Storage service has supported the concept of multi-attach.
However, the Compute service, as of the Pike release, does not yet have
support to leverage multi-attach. Concurrently, multi-attach requires the
backend volume driver running as part of the Block Storage service to
contain support for multi-attach volumes.
When support for storage interfaces was added to the Bare Metal service,
specifically for the ``cinder`` storage interface, the concept of volume
multi-attach was accounted for, however has not been fully tested,
and is unlikely to be fully tested until there is Compute service integration
as well as volume driver support.
The data model for storage of volume targets in the Bare Metal service
has no constraints on the same target volume from being utilized.
When interacting with the Block Storage service, the Bare Metal service
will prevent the use of volumes that are being reported as ``in-use``
if they do not explicitly support multi-attach.