From ce85cd94a304b9ec2263c35b6754fb71849aa282 Mon Sep 17 00:00:00 2001 From: Shilla Saebi Date: Fri, 27 Jun 2014 20:20:06 -0400 Subject: [PATCH] copy-edit and clean up of module001-ch009-vm-placement MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit copy-edit and clean up of document added the for formality capitalized Nova-scheduler changed only and supports to make sense removed , and ‘too” added , and that changed define to defined removed So, added the, changed to weighed Change-Id: I47380b6cd0a811b4c9af0643fc55784f1f929942 --- .../module001-ch009-vm-placement.xml | 36 +++++++++---------- 1 file changed, 18 insertions(+), 18 deletions(-) diff --git a/doc/training-guides/module001-ch009-vm-placement.xml b/doc/training-guides/module001-ch009-vm-placement.xml index e9eb9742..3222b956 100644 --- a/doc/training-guides/module001-ch009-vm-placement.xml +++ b/doc/training-guides/module001-ch009-vm-placement.xml @@ -20,17 +20,17 @@ - Just as shown by above figure, nova-scheduler interacts with + Just as shown by the above figure, nova-scheduler interacts with other components through queue and central database repo. For - scheduling, queue is the essential communications hub. + scheduling, the queue is the essential communications hub. All compute nodes (also known as hosts in terms of OpenStack) periodically publish their status, resources available and hardware capabilities to nova-scheduler through the queue. - nova-scheduler then collects this data and uses it to make + Nova-scheduler then collects this data and uses it to make decisions when a request comes in. By default, the compute scheduler is configured as a filter scheduler, as described in the next section. In the default - configuration, this scheduler considers hosts that meet all the + configuration, this scheduler considers hosts that meet all of the following criteria: @@ -49,7 +49,7 @@ Filter Scheduler The Filter Scheduler supports filtering and weighting to make informed decisions on where a new instance should be created. - This Scheduler supports only working with Compute Nodes. + This Scheduler only supports working with Compute Nodes. Filtering
@@ -65,7 +65,7 @@ and finally chooses hosts for the requested number of instances (each time it chooses the most weighed host and appends it to the list of selected hosts). - If it turns up, that it can’t find candidates for the next + If it turns up that it can’t find candidates for the next instance, it means that there are no more appropriate hosts where the instance could be scheduled. If we speak about filtering and weighting, their work is @@ -76,7 +76,7 @@ (nova.scheduler.filters): - AllHostsFilter - frankly speaking, this filter does no + AllHostsFilter - This filter does no operation. It passes all the available hosts. @@ -138,15 +138,15 @@ Here ram_allocation_ratio means the virtual RAM to physical RAM allocation ratio (it is 1.5 by default). Really, nice and simple. - Next standard filter to describe is AvailabilityZoneFilter - and it isn’t difficult too. This filter just looks at the + The next standard filter to describe is AvailabilityZoneFilter + and it isn’t difficult. This filter just looks at the availability zone of compute node and availability zone from the properties of the request. Each Compute service has its - own availability zone. So deployment engineers have an option + own availability zone, so that deployment engineers have an option to run scheduler with availability zones support and can configure availability zones on each compute host. This - classes method host_passes returns True if availability zone - mentioned in request is the same on the current compute + classes method host_passes returns True if the availability zone + mentioned in the request is the same on the current compute host. The ImagePropertiesFilter filters hosts based on the architecture, hypervisor type, and virtual machine mode @@ -154,7 +154,7 @@ host that supports the arm architecture on a qemu compute host. The ImagePropertiesFilter will only pass hosts that can satisfy this request. These instance properties are populated - from properties define on the instance’s image. E.g. an image + from properties defined on the instance’s image. E.g. an image can be decorated with these properties using glance image-update img-uuid --property architecture=arm --property hypervisor_type=qemu Only hosts that satisfy these @@ -171,20 +171,20 @@ are passed if no extra_specs are specified. ComputeFilter is quite simple and passes any host whose Compute service is enabled and operational. - Now we are going to IsolatedHostsFilter. There can be some + Now we are going to the IsolatedHostsFilter. There can be some special hosts reserved for specific images. These hosts are - called isolated. So the images to run on the isolated hosts - are also called isolated. This Scheduler checks if + called isolated. The images to run on the isolated hosts + are also called isolated. This Scheduler checks if the image_isolated flag named in instance specifications is the same that the host has. Weights Filter Scheduler uses so-called weights during its work. - The Filter Scheduler weights hosts based on the config + The Filter Scheduler weighs hosts based on the config option scheduler_weight_classes, this defaults to nova.scheduler.weights.all_weighers, which selects the only - weigher available – the RamWeigher. Hosts are then weighted and + weigher available – the RamWeigher. Hosts are then weighed and sorted with the largest weight winning. Filter Scheduler finds local list of acceptable hosts by repeated filtering and weighing. Each time it chooses a host, it