Acropolis Dynamic Scheduling proactively monitors the nutanix cluster for any compute and storage I/O contentions or hotspots over a period of time. If ADS detects a problem, ADS creates a migration plan that eliminates hotspots in the cluster and migrates VMs from one host to another.
We can monitor VM migration tasks from the Task dashboard of the Prism Element web console
Following are the advantages of ADS
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ADS improves the initial placement of the VMs depending on the VM configuration
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Nutanix volumes uses ADS for balancing sessions of the externally available iSCSI targets
By default, ADS is enabled and Nutanix recommends to keep this feature enabled.
ADS monitors the following features:
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VM CPU Utilization: Total CPU usage of each guest VM.
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Storage CPU Utilization: Storage Controller (Stargate) CPU usage per VM or iSCSI target.
ADS does not monitor memory and networking usage
Lazan is the ADS service in an AHV cluster. AOS selects a Lazan manager and Lazan solver among the hosts in the cluster to effectively manage ADS operations
Lazan runs every 15 minutes and analyzes the resource usage for at least that period of time. If the resource utilization of an AHV host remains >85% for the span of 15 minutes.
Lazan triggers migration tasks to remove the hotspot
Enabling ADS:
If you have disabled the ADS feature and want to enable the feature, perform the following procedure
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Log on to a controller VM in your cluster with SSH
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Enable ADS: nutanix@CVM$ acli ads.update enable=true
Even after you disable the feature, the checks for the contentions or hotspots run in the background and if any anomalies are detected, an alert is raised in the Alerts dashboard. However, no action is taken by ADS to solve the contentions. You need to manually take the remedial actions or you can enable the feature.