Boot From Volume

Boot From Volume


The Bare Metal service supports booting from a Cinder iSCSI volume as of the Pike release. This guide will primarily deal with this use case, but will be updated as more paths for booting from a volume, such as FCoE, are introduced.


Currently booting from a volume requires:

  • Bare Metal service version 9.0.0
  • Bare Metal API microversion 1.33 or later
  • A driver that utilizes the PXE boot mechanism. Currently booting from a volume is supported by the reference drivers that utilize PXE boot mechanisms when iPXE is enabled.
  • iPXE is an explicit requirement, as it provides the mechanism that attaches and initiates booting from an iSCSI volume.

Conductor Configuration

In ironic.conf, you can specify a list of enabled storage interfaces. Check [DEFAULT]enabled_storage_interfaces in your ironic.conf to ensure that your desired interface is enabled. For example, to enable the cinder and noop storage interfaces:

enabled_storage_interfaces = cinder,noop

If you want to specify a default storage interface rather than setting the storage interface on a per node basis, set [DEFAULT]default_storage_interface in ironic.conf. The default_storage_interface will be used for any node that doesn’t have a storage interface defined.

Node Configuration

Storage Interface

You will need to specify what storage interface the node will use to handle storage operations. For example, to set the storage interface to cinder on an existing node:

openstack --os-baremetal-api-version 1.33 baremetal node set \
          --storage-interface cinder $NODE_UUID

A default storage interface can be specified in ironic.conf. See the Conductor Configuration section for details.

iSCSI Configuration

In order for a bare metal node to boot from an iSCSI volume, the iscsi_boot capability for the node must be set to True. For example, if you want to update an existing node to boot from volume:

openstack --os-baremetal-api-version 1.33 baremetal node set \
          --property capabilities=iscsi_boot:True $NODE_UUID

You will also need to create a volume connector for the node, so the storage interface will know how to communicate with the node for storage operation. In the case of iSCSI, you will need to provide an iSCSI Qualifying Name (IQN) 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 $NODE_UUID --type iqn --connector-id$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


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.

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