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operations-guide
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Merge "Fix documentation for usage of Nova Cells (v2)"

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Zuul 2019-07-23 06:56:53 +00:00 committed by Gerrit Code Review
parent a3c10f68b9 6f080590b6
commit 34173da672
1 changed files with 14 additions and 16 deletions
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doc/source/ops-capacity-planning-scaling.rst
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@ -197,8 +197,8 @@ segregation method currently provided by OpenStack Compute.
- Availability zones - Availability zones
- Host aggregates - Host aggregates
* - **Use** * - **Use**
- A single :term:`API endpoint` for compute, or you require a second - Shard and scale compute deployment while maintaining a single
level of scheduling. :term:`API endpoint`.
- Discrete regions with separate API endpoints and no coordination - Discrete regions with separate API endpoints and no coordination
between regions. between regions.
- Logical separation within your nova deployment for physical isolation - Logical separation within your nova deployment for physical isolation
@ -212,8 +212,8 @@ segregation method currently provided by OpenStack Compute.
- A single-site cloud with equipment fed by separate power supplies. - A single-site cloud with equipment fed by separate power supplies.
- Scheduling to hosts with trusted hardware support. - Scheduling to hosts with trusted hardware support.
* - **Overhead** * - **Overhead**
- Considered experimental. A new service, nova-cells. Each cell has a full - Each Cell contains instances of services with overlapping
nova installation except nova-api. functionality.
- A different API endpoint for every region. Each region has a full nova - A different API endpoint for every region. Each region has a full nova
installation. installation.
- Configuration changes to ``nova.conf``. - Configuration changes to ``nova.conf``.
@ -227,22 +227,20 @@ segregation method currently provided by OpenStack Compute.
Cells and regions Cells and regions
----------------- -----------------
OpenStack Compute cells are designed to allow running the cloud in a `OpenStack Compute Cells <https://docs.openstack.org/nova/latest/user/cells.html>`_
are designed to allow running the cloud in a
distributed fashion without having to use more complicated technologies, distributed fashion without having to use more complicated technologies,
or be invasive to existing nova installations. Hosts in a cloud are or be invasive to existing nova installations. Hosts in a cloud are
partitioned into groups called *cells*. Cells are configured in a tree. partitioned into groups called *Cells*. Cells are configured in a tree.
The top-level cell ("API cell") has a host that runs the ``nova-api`` The top-level Cell ("API cell") has a host that runs the ``nova-api``
service, but no ``nova-compute`` services. Each child cell runs all of service, but no ``nova-compute`` services. The ``nova-compute`` runs
the other typical ``nova-*`` services found in a regular installation, in a child Cell.
except for the ``nova-api`` service. Each cell has its own message queue Each Cell has its own message queue and database service.
and database service and also runs ``nova-cells``, which manages the
communication between the API cell and child cells.
This allows for a single API server being used to control access to This allows for a single API server being used to control access to
multiple cloud installations. Introducing a second level of scheduling multiple compute installations with the usage of multiple Cells.
(the cell selection), in addition to the regular ``nova-scheduler`` See `Nova Cells V2 Layout <https://docs.openstack.org/nova/latest/user/cellsv2-layout.html>`_
selection of hosts, provides greater flexibility to control where for further documentation.
virtual machines are run.
Unlike having a single API endpoint, regions have a separate API Unlike having a single API endpoint, regions have a separate API
endpoint per installation, allowing for a more discrete separation. endpoint per installation, allowing for a more discrete separation.