Description of configuration options for scheduling

Configuration option = Default value	Description
[DEFAULT]
aggregate_image_properties_isolation_namespace = None	(StrOpt) Force the filter to consider only keys matching the given namespace.
aggregate_image_properties_isolation_separator = .	(StrOpt) The separator used between the namespace and keys
cpu_allocation_ratio = 16.0	(FloatOpt) Virtual CPU to physical CPU allocation ratio which affects all CPU filters. This configuration specifies a global ratio for CoreFilter. For AggregateCoreFilter, it will fall back to this configuration value if no per-aggregate setting found.
disk_allocation_ratio = 1.0	(FloatOpt) Virtual disk to physical disk allocation ratio
isolated_hosts =	(ListOpt) Host reserved for specific images
isolated_images =	(ListOpt) Images to run on isolated host
max_instances_per_host = 50	(IntOpt) Ignore hosts that have too many instances
max_io_ops_per_host = 8	(IntOpt) Ignore hosts that have too many builds/resizes/snaps/migrations
ram_allocation_ratio = 1.5	(FloatOpt) Virtual ram to physical ram allocation ratio which affects all ram filters. This configuration specifies a global ratio for RamFilter. For AggregateRamFilter, it will fall back to this configuration value if no per-aggregate setting found.
ram_weight_multiplier = 1.0	(FloatOpt) Multiplier used for weighing ram. Negative numbers mean to stack vs spread.
reserved_host_disk_mb = 0	(IntOpt) Amount of disk in MB to reserve for the host
reserved_host_memory_mb = 512	(IntOpt) Amount of memory in MB to reserve for the host
restrict_isolated_hosts_to_isolated_images = True	(BoolOpt) Whether to force isolated hosts to run only isolated images
scheduler_available_filters = ['nova.scheduler.filters.all_filters']	(MultiStrOpt) Filter classes available to the scheduler which may be specified more than once. An entry of "nova.scheduler.filters.standard_filters" maps to all filters included with nova.
scheduler_default_filters = RetryFilter, AvailabilityZoneFilter, RamFilter, ComputeFilter, ComputeCapabilitiesFilter, ImagePropertiesFilter, ServerGroupAntiAffinityFilter, ServerGroupAffinityFilter	(ListOpt) Which filter class names to use for filtering hosts when not specified in the request.
scheduler_driver = nova.scheduler.filter_scheduler.FilterScheduler	(StrOpt) Default driver to use for the scheduler
scheduler_driver_task_period = 60	(IntOpt) How often (in seconds) to run periodic tasks in the scheduler driver of your choice. Please note this is likely to interact with the value of service_down_time, but exactly how they interact will depend on your choice of scheduler driver.
scheduler_host_manager = nova.scheduler.host_manager.HostManager	(StrOpt) The scheduler host manager class to use
scheduler_host_subset_size = 1	(IntOpt) New instances will be scheduled on a host chosen randomly from a subset of the N best hosts. This property defines the subset size that a host is chosen from. A value of 1 chooses the first host returned by the weighing functions. This value must be at least 1. Any value less than 1 will be ignored, and 1 will be used instead
scheduler_json_config_location =	(StrOpt) Absolute path to scheduler configuration JSON file.
scheduler_manager = nova.scheduler.manager.SchedulerManager	(StrOpt) Full class name for the Manager for scheduler
scheduler_max_attempts = 3	(IntOpt) Maximum number of attempts to schedule an instance
scheduler_topic = scheduler	(StrOpt) The topic scheduler nodes listen on
scheduler_weight_classes = nova.scheduler.weights.all_weighers	(ListOpt) Which weight class names to use for weighing hosts
[cells]
ram_weight_multiplier = 10.0	(FloatOpt) Multiplier used for weighing ram. Negative numbers mean to stack vs spread.
scheduler_filter_classes = nova.cells.filters.all_filters	(ListOpt) Filter classes the cells scheduler should use. An entry of "nova.cells.filters.all_filters" maps to all cells filters included with nova.
scheduler_retries = 10	(IntOpt) How many retries when no cells are available.
scheduler_retry_delay = 2	(IntOpt) How often to retry in seconds when no cells are available.
scheduler_weight_classes = nova.cells.weights.all_weighers	(ListOpt) Weigher classes the cells scheduler should use. An entry of "nova.cells.weights.all_weighers" maps to all cell weighers included with nova.
[metrics]
required = True	(BoolOpt) How to treat the unavailable metrics. When a metric is NOT available for a host, if it is set to be True, it would raise an exception, so it is recommended to use the scheduler filter MetricFilter to filter out those hosts. If it is set to be False, the unavailable metric would be treated as a negative factor in weighing process, the returned value would be set by the option weight_of_unavailable.
weight_multiplier = 1.0	(FloatOpt) Multiplier used for weighing metrics.
weight_of_unavailable = -10000.0	(FloatOpt) The final weight value to be returned if required is set to False and any one of the metrics set by weight_setting is unavailable.
weight_setting =	(ListOpt) How the metrics are going to be weighed. This should be in the form of "<name1>=<ratio1>, <name2>=<ratio2>, ...", where <nameX> is one of the metrics to be weighed, and <ratioX> is the corresponding ratio. So for "name1=1.0, name2=-1.0" The final weight would be name1.value * 1.0 + name2.value * -1.0.