Specify compute hosts with SSDs

scheduler_driver = nova.scheduler.filter_scheduler.FilterScheduler
scheduler_available_filters = nova.scheduler.filters.all_filters
scheduler_default_filters =AggregateInstanceExtraSpecsFilter

首先在nova.conf中配置以上调度

在nova availability zone中创建 fast-io host aggregate

$ nova aggregate-create fast-io nova
+----+---------+-------------------+-------+----------+
| Id | Name    | Availability Zone | Hosts | Metadata |
+----+---------+-------------------+-------+----------+
|   | fast-io | nova              |       |          |
+----+---------+-------------------+-------+----------+

添加ssd=true key-value pair to the aggregate

$ nova aggregate-set-metadata  ssd=true
+----+---------+-------------------+-------+-------------------+
| Id | Name    | Availability Zone | Hosts | Metadata          |
+----+---------+-------------------+-------+-------------------+
|   | fast-io | nova              | []    | {u'ssd': u'true'} |
+----+---------+-------------------+-------+-------------------+

把node1/2添加到aggregate

$ nova aggregate-add-host  node1
+----+---------+-------------------+-----------+-------------------+
| Id | Name    | Availability Zone | Hosts      | Metadata          |
+----+---------+-------------------+------------+-------------------+
|   | fast-io | nova              | [u'node1'] | {u'ssd': u'true'} |
+----+---------+-------------------+------------+-------------------+

$ nova aggregate-add-host  node2
+----+---------+-------------------+---------------------+-------------------+
| Id | Name    | Availability Zone | Hosts                | Metadata          |
+----+---------+-------------------+----------------------+-------------------+
|   | fast-io | nova              | [u'node1', u'node2'] | {u'ssd': u'true'} |
+----+---------+-------------------+----------------------+-------------------+

创建ssd.large flavor， ID of 6, 8 GB of RAM, 80 GB root disk, and four vCPUs.

$ nova flavor-create ssd.large
+----+-----------+-----------+------+-----------+------+-------+-------------+-----------+
| ID | Name      | Memory_MB | Disk | Ephemeral | Swap | VCPUs | RXTX_Factor | Is_Public |
+----+-----------+-----------+------+-----------+------+-------+-------------+-----------+
|   | ssd.large |       |    |          |      |      | 1.0         | True      |
+----+-----------+-----------+------+-----------+------+-------+-------------+-----------+

设置aggregate_instance_extra_specs filter的key-value pairs:

$ nova flavor-key ssd.large set  aggregate_instance_extra_specs:ssd=true

该filter的实现在：nova/scheduler/filters/aggregate_instance_extra_specs.py

$ nova flavor-show ssd.large
+----------------------------+--------------------------------------------------+
| Property                   | Value                                            |
+----------------------------+--------------------------------------------------+
| OS-FLV-DISABLED:disabled   | False                                            |
| OS-FLV-EXT-DATA:ephemeral  |                                                 |
| disk                       |                                                |
| extra_specs                | {u'aggregate_instance_extra_specs:ssd': u'true'} |
| id                         |                                                 |
| name                       | ssd.large                                        |
| os-flavor-access:is_public | True                                             |
| ram                        |                                              |
| rxtx_factor                | 1.0                                              |
| swap                       |                                                  |
| vcpus                      |                                                 |
+----------------------------+--------------------------------------------------+

现在使用ssd.large flavor来创建instance时，scheduler 只会考虑带有ssd=true key-value pair的host，也就是node1/2.

http://docs.openstack.org/liberty/config-reference/content/section_compute-scheduler.html