openstack/openstack-manuals
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Merge "Support for Cinder volume replication"

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Jenkins 2015-10-22 11:24:14 +00:00 committed by Gerrit Code Review
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doc/admin-guide-cloud/source/blockstorage_over_subscription.rst
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@ -93,6 +93,38 @@ The above extra specs are used by the scheduler to find a back end that
supports thin provisioning, thick provisioning, or both to match the needs
of a specific volume type.
Volume replication extra specs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
OpenStack Block Storage has the ability to create volume replicas.
Cloud administrators can define a storage policy that includes
replication by adjusting the cinder volume driver. Volume replication
for OpenStack Block Storage helps safeguard OpenStack environments from
data loss during disaster recovery.
To enable replication when creating volume types, configure the cinder
volume with ``capabilities:replication="<is> True"``.
Each volume created with the replication capability set to `True`
generates a copy of the volume on a storage back end.
One use case for replication involves an OpenStack cloud environment
installed accross two data centers located nearby each other. The
distance between the two data centers in this use case is the length of
a city.
At each data center, a cinder host supports the Block Storage service.
Both data centers include storage back ends.
Depending on the storage requirements, there can be one or two cinder
hosts. The cloud administrator accesses the
:file:`/etc/cinder/cinder.conf` configuration file and sets
``capabilities:replication="<is> True"``.
If one data center experiences a service failure, cloud administrators
can redeploy the VM. The VM will run using a replicated, backed up
volume on a host in the second data center.
Capacity filter
~~~~~~~~~~~~~~~