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-rw-r--r-- | doc/source/admin/manage-volumes.rst | 64 |
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diff --git a/doc/source/admin/manage-volumes.rst b/doc/source/admin/manage-volumes.rst index 5b6f156983..2c8374a7f4 100644 --- a/doc/source/admin/manage-volumes.rst +++ b/doc/source/admin/manage-volumes.rst @@ -11,3 +11,67 @@ are of primary interest. Refer to the `block storage service CLI guide on managing volumes <https://docs.openstack.org/cinder/latest/cli/cli-manage-volumes.html>`_. + + +Volume multi-attach +------------------- + +Nova `added support for multiattach volumes`_ in the 17.0.0 Queens release. + +This document covers the nova-specific aspects of this feature. Refer +to the `block storage admin guide`_ for more details about creating +multiattach-capable volumes. + +Boot from volume and attaching a volume to a server that is not +SHELVED_OFFLOADED is supported. Ultimately the ability to perform +these actions depends on the compute host and hypervisor driver that +is being used. + +Requirements +~~~~~~~~~~~~ + +* The minimum required compute API microversion for attaching a + multiattach-capable volume to more than one server is `2.60`_. +* Cinder 12.0.0 (Queens) or newer is required. +* The ``nova-compute`` service must be running at least Queens release level + code (17.0.0) and the hypervisor driver must support attaching block storage + devices to more than one guest. Refer to the `feature support matrix`_ for + details on which compute drivers support volume multiattach. +* When using the libvirt compute driver, the following native package versions + determine multiattach support: + + * libvirt must be greater than or equal to 3.10, or + * qemu must be less than 2.10 + +* Swapping an *in-use* multiattach volume is not supported (this is actually + controlled via the block storage volume retype API). + +Known issues +~~~~~~~~~~~~ + +* Creating multiple servers in a single request with a multiattach-capable + volume as the root disk is not yet supported: https://bugs.launchpad.net/nova/+bug/1747985 +* Subsequent attachments to the same volume are all attached in *read/write* + mode by default in the block storage service. A future change either in nova + or cinder may address this so that subsequent attachments are made in + *read-only* mode, or such that the mode can be specified by the user when + attaching the volume to the server. + +Testing +~~~~~~~ + +Continuous integration testing of the volume multiattach feature is done +via the ``nova-multiattach`` job, defined in the `nova repository`_. + +The tests are defined in the `tempest repository`_. + +The CI job is setup to run with the **libvirt** compute driver and the **lvm** +volume back end. It purposefully does not use the Pike Ubuntu Cloud Archive +package mirror so that it gets qemu<2.10. + +.. _added support for multiattach volumes: https://specs.openstack.org/openstack/nova-specs/specs/queens/implemented/multi-attach-volume.html +.. _block storage admin guide: https://docs.openstack.org/cinder/latest/admin/blockstorage-volume-multiattach.html +.. _2.60: https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#maximum-in-queens +.. _feature support matrix: https://docs.openstack.org/nova/latest/user/support-matrix.html#operation_multiattach_volume +.. _nova repository: http://git.openstack.org/cgit/openstack/nova/tree/playbooks/legacy/nova-multiattach/run.yaml +.. _tempest repository: http://codesearch.openstack.org/?q=CONF.compute_feature_enabled.volume_multiattach&i=nope&files=&repos=tempest |