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navsection: admin
-title: Using AWS Spot instances
+title: Using Preemptible instances
...
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SPDX-License-Identifier: CC-BY-SA-3.0
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-This page describes how to set up crunch to take advantage of "Amazon's EC2 spot instances":https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-spot-instances.html.
+This page describes how to enable preemptible instances. Preemptible instances typically offer lower cost computation with a tradeoff of lower service guarantees. If a compute node is preempted, Arvados will restart the computation on a new instance.
+
+Currently Arvados supports preemptible instances using AWS spot instances.
h2. Configuration
-To use spot instances, set @UsePreemptibleInstances: true@ and add entries to @InstanceTypes@ with @Preemptible: true@. Typically you want to add both preemptible and non-preemptible entries for each cloud provider VM type. The @Price@ for preemptible instances is the maximum bid price, the actual price paid is dynamic and may be lower. For example:
+To use preemptible instances, set @UsePreemptibleInstances: true@ and add entries to @InstanceTypes@ with @Preemptible: true@ to @config.yml@. Typically you want to add both preemptible and non-preemptible entries for each cloud provider VM type. The @Price@ for preemptible instances is the maximum bid price, the actual price paid is dynamic and may be lower. For example:
<pre>
Clusters:
- uuid_prefix:
+ ClusterID:
Containers:
UsePreemptibleInstances: true
InstanceTypes:
m4.large:
- Preemptible: false
+ Preemptible: false
ProviderType: m4.large
VCPUs: 2
RAM: 8GiB
AddedScratch: 32GB
Price: 0.1
m4.large.spot:
- Preemptible: true
+ Preemptible: true
ProviderType: m4.large
VCPUs: 2
RAM: 8GiB
Price: 0.1
</pre>
-When @UsePreemptibleInstances@ is enabled, child containers (workflow steps) will automatically be made preemptable. If the instance running a step is preempted, it will be restarted on a new instance. However, because preempting the workflow runner would cancel the entire workflow, the workflow runner runs in a reserved (nonpreemptable) instance.
+When @UsePreemptibleInstances@ is enabled, child containers (workflow steps) will automatically be made preemptible. Note that because preempting the workflow runner would cancel the entire workflow, the workflow runner runs in a reserved (non-preemptible) instance.
+
+If you are using "arvados-dispatch-cloud":{{site.baseurl}}/install/crunch2-cloud/install-dispatch-cloud.html no additional configuration is required.
-If you are using "crunch-dispatch-cloud":{{site.baseurl}}/install/install-dispatch-cloud.html no additional configuration is required.
+h2. Preemptible instances on AWS
-If you are using the legacy Nodemanager, "see below":#nodemanager .
+For general information, see "using Amazon EC2 spot instances":https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-spot-instances.html .
-h3. AWS Permissions
+h3. Permissions
When requesting spot instances, Amazon's API may return an authorization error depending on how users and permissions are set on the account. If this is the case check logs for this error:
h3. Cost Tracking
-Amazon's Spot instances prices are declared at instance request time and defined by the maximum price that the user is willing to pay per hour. By default, this price is the same amount as the on-demand version of each instance type, and this setting is the one that nodemanager uses for now, as it doesn't include any pricing data to the spot instance request.
+Amazon's Spot instances prices are declared at instance request time and defined by the maximum price that the user is willing to pay per hour. By default, this price is the same amount as the on-demand version of each instance type, and this setting is the one that @arvados-dispatch-cloud@ uses for now, as it doesn't include any pricing data to the spot instance request.
The real price that a spot instance has at any point in time is discovered at the end of each usage hour, depending on instance demand. For this reason, AWS provides a data feed subscription to get hourly logs, as described on "Amazon's User Guide":https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-data-feeds.html.
-h2(#nodemanager). Nodemanager
-
-If you are using the legacy Nodemanager, its config file must also declare preemptible instance sizes, which must match the API server's @InstanceTypes@:
-
-<pre>
-[Size m4.large]
-cores = 2
-scratch = 32000
-
-[Size m4.large.spot]
-cores = 2
-instance_type = m4.large
-preemptible = true
-scratch = 32000
-</pre>
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