Matt Riedemann e9dd8c0f48 Drop nova-multiattach job

The dependent tempest change enables the volume multiattach
tests in the tempest-full and tempest-slow jobs, on which
nova already gates, which allows us to drop the special
nova-multiattach job which is mostly redundant test coverage
of the other tempest.api.compute.* tests, and allows us to
run one fewer job on nova/cinder/tempest changes in Stein.

The docs are updated to reflect the source of the testing
now.

Also depends on cinder dropping its usage of the nova-multiattach
job before we can drop the job definition from nova.

Depends-On: https://review.openstack.org/606978
Depends-On: https://review.openstack.org/606985
Change-Id: I744afa1df9a6ed8e0eba4310b20c33755ce1ba88

2019-02-05 09:13:02 -05:00

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Manage volumes

Depending on the setup of your cloud provider, they may give you an endpoint to use to manage volumes. You can use the openstack CLI to manage volumes.

For the purposes of the compute service, attaching, detaching and creating a server from a volume </user/launch-instance-from-volume> are of primary interest.

Refer to the CLI documentation <cli/command-objects/volume.html> for more information.

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 <admin/blockstorage-volume-multiattach.html> 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.

There is also a recorded overview and demo for volume multi-attach.

Requirements

The minimum required compute API microversion for attaching a multiattach-capable volume to more than one server is 2.60 <api-microversion-queens>.
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 /user/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 tempest-full and tempest-slow jobs, which, along with the tests themselves, are defined in the tempest repository.

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