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A company is using Azure Virtual Machine Scale Sets (VMSS) to host a web application. Due to varying traffic patterns, the application experiences significant spikes in demand during peak hours and very low usage overnight. To optimize costs and ensure performance, you need to configure the VMSS to automatically adjust the number of VM instances based on CPU utilization, and also scale down to a minimum number of instances during off-peak hours. Which VMSS feature should you implement?
- ACustom Script Extension
- BUpdate Domains
- CAutoscale
- DManual Scaling
Show answer & explanationAnswer & explanation
Correct answer: C. Autoscale
Azure Virtual Machine Scale Sets (VMSS) Autoscale allows you to automatically increase or decrease the number of VM instances based on predefined metrics, schedules, or a combination. This directly addresses the need to adjust instances based on CPU utilization and scale down during off-peak hours.
Why the other options are wrong
- A. Custom Script Extension runs scripts on VMs but is not designed for dynamic instance count management based on performance metrics.
- B. Update Domains are used to ensure that not all VMs in a scale set are updated simultaneously, which is related to availability during maintenance, not dynamic scaling based on demand.
- D. Manual Scaling requires administrator intervention and does not automatically adjust to demand.
VMSS Autoscale
A feature of Azure Virtual Machine Scale Sets that automatically adjusts the number of VM instances based on demand or a defined schedule.
- Increases/decreases instances based on metrics (e.g., CPU, memory).
- Can be configured with minimum and maximum instance counts.
- Helps optimize costs and maintain performance.
Memory trick: For automatic scaling, just 'Autoscale' your VMSS.