Virtual Machine (VM) Pool usage scenario

Because the VM pool mechanism manages the VMs, the VM pool creates a new VM if it detects a new image of a tenant.

This happens in several situations:

• There are still VMs with the old image in the pool.

  While the new version of the VM is being prepared, the new version of the image can successfully create the VM.

• In this preparation process, when a user logs in and allocates a VM, the old version of the VM is preferred.

• If the new version image has issues and cannot be created in the VM, the pool allocates the old VM until no VM can be allocated.

• If the new version image has issues and cannot be used for VM creation (VM creation failed five times), the VM pool enters an error state.

After the VM pool enters the error state, the pool does not create a new VM until a new update operation is triggered by changing the pool area or sending a new image from IMS. If the account's credits are used up, all unallocated and allocated VMs are automatically shut down.

If the account's credit is used up and the VM pool cannot create the VM, then the VM pool enters a runout state. The VM pool temporarily changes to a running state when:

• A new version of the AVEVA Production Accounting image is deployed.

• The VM pool region is updated.

However, after five launches in which the account's credit remains zero, then the VM pool returns to the runout state.