vCPU limits can significantly impact running multiple VMs on the free tier in cloud services. Here's how:
1. Resource Allocation: Each VM requires a certain number of vCPUs, which are virtual representations of physical CPU cores. The free tier typically offers limited vCPU resources. For example, in Oracle Cloud, you can have up to 4 VMs with specific configurations like 1 vCPU for x86 VMs or distribute resources differently for ARM VMs[1]. In AWS, the free tier often includes burstable instances like t2.micro with 1 vCPU[5].
2. Performance Impact: Overprovisioning vCPUs (assigning more vCPUs than available physical cores) can lead to performance issues. While it's technically possible to run more VMs than physical cores, this can result in significant performance degradation due to increased contention for physical resources[2][6].
3. Idle Reclamation: Some cloud providers, like Oracle, may reclaim idle instances if they don't meet certain utilization thresholds, which can affect how you manage multiple VMs on the free tier[1].
4. Quota Management: Cloud services often enforce quotas on vCPUs per region or VM family. Exceeding these quotas can prevent deploying additional VMs, so managing vCPU allocation is crucial for running multiple VMs within free tier limits[3][7].
In summary, while you can run multiple VMs on the free tier, you must carefully manage vCPU allocation to avoid performance issues and ensure compliance with provider quotas and policies.
Citations:
[1] https://www.reddit.com/r/oraclecloud/comments/16ls9kv/can_i_create_three_vms_being_free_tier/
[2] https://superuser.com/questions/1602681/what-are-the-limits-of-allocating-my-cpu-cores-to-vms
[3] https://learn.microsoft.com/en-us/azure/virtual-machines/quotas
[4] https://community.broadcom.com/vmware-cloud-foundation/discussion/definitions-of-vcpu-reservations-limit
[5] https://repost.aws/questions/QUSHASTA-iQFKur95RvjdUSw/vcpu-capacity-limit-in-free-tier
[6] https://gabesvirtualworld.com/how-too-many-vcpus-can-negatively-affect-your-performance/
[7] https://learn.microsoft.com/en-us/azure/quotas/per-vm-quota-requests
[8] https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/azure-subscription-service-limits