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Add doc for vm_workload_consolidation strategy

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This patch adds documentation on requirements for
vm_workload_consolidation strategy.

Change-Id: I304644138b34658b09f7cd8f29eb089757807b61
Closes-bug: #1640820
This commit is contained in:
Bruno Grazioli
2016-11-10 17:52:23 +01:00
parent 21abbb4cd1
commit 5c793894ab
2 changed files with 137 additions and 48 deletions
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85
watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py
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@@ -16,6 +16,42 @@
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""
*VM Workload Consolidation Strategy*
A load consolidation strategy based on heuristic first-fit
algorithm which focuses on measured CPU utilization and tries to
minimize hosts which have too much or too little load respecting
resource capacity constraints.
This strategy produces a solution resulting in more efficient
utilization of cluster resources using following four phases:
* Offload phase - handling over-utilized resources
* Consolidation phase - handling under-utilized resources
* Solution optimization - reducing number of migrations
* Disability of unused compute nodes
A capacity coefficients (cc) might be used to adjust optimization
thresholds. Different resources may require different coefficient
values as well as setting up different coefficient values in both
phases may lead to to more efficient consolidation in the end.
If the cc equals 1 the full resource capacity may be used, cc
values lower than 1 will lead to resource under utilization and
values higher than 1 will lead to resource overbooking.
e.g. If targeted utilization is 80 percent of a compute node capacity,
the coefficient in the consolidation phase will be 0.8, but
may any lower value in the offloading phase. The lower it gets
the cluster will appear more released (distributed) for the
following consolidation phase.
As this strategy leverages VM live migration to move the load
from one compute node to another, this feature needs to be set up
correctly on all compute nodes within the cluster.
This strategy assumes it is possible to live migrate any VM from
an active compute node to any other active compute node.
"""
from oslo_log import log
import six
@@ -31,54 +67,7 @@ LOG = log.getLogger(__name__)
class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
"""VM Workload Consolidation Strategy.
*Description*
A load consolidation strategy based on heuristic first-fit
algorithm which focuses on measured CPU utilization and tries to
minimize hosts which have too much or too little load respecting
resource capacity constraints.
This strategy produces a solution resulting in more efficient
utilization of cluster resources using following four phases:
* Offload phase - handling over-utilized resources
* Consolidation phase - handling under-utilized resources
* Solution optimization - reducing number of migrations
* Disability of unused compute nodes
A capacity coefficients (cc) might be used to adjust optimization
thresholds. Different resources may require different coefficient
values as well as setting up different coefficient values in both
phases may lead to to more efficient consolidation in the end.
If the cc equals 1 the full resource capacity may be used, cc
values lower than 1 will lead to resource under utilization and
values higher than 1 will lead to resource overbooking.
e.g. If targeted utilization is 80 percent of a compute node capacity,
the coefficient in the consolidation phase will be 0.8, but
may any lower value in the offloading phase. The lower it gets
the cluster will appear more released (distributed) for the
following consolidation phase.
As this strategy laverages VM live migration to move the load
from one compute node to another, this feature needs to be set up
correctly on all compute nodes within the cluster.
This strategy assumes it is possible to live migrate any VM from
an active compute node to any other active compute node.
*Requirements*
* You must have at least 2 physical compute nodes to run this strategy.
*Limitations*
<None>
*Spec URL*
https://github.com/openstack/watcher-specs/blob/master/specs/mitaka/implemented/zhaw-load-consolidation.rst
""" # noqa
"""VM Workload Consolidation Strategy"""
def __init__(self, config, osc=None):
super(VMWorkloadConsolidation, self).__init__(config, osc)