Scalability

Horizontal scaling can be done on the VMs, but it will require a manual process as the Mirth® Connect by NextGen Healthcare clustering plugin will need to be configured to add/remove nodes within the cluster. Auto-scaling horizontally can be achieved on the Azure VMs by implementing the Azure Virtual Machine scale sets, but the manual process of configuring the Mirth® Connect by NextGen Healthcare advance clustering plugin limits the full automation.

Vertical scaling is also available with Azure VMs with the use of the Azure Virtual Machine scale sets as well. The scale set can be programmed to trigger based on certain metrics, such as CPU, memory, disk statistics. The trigger can then be used to perform the action of scaling up or down the virtual machine's resources accordingly. The following link provides the details on vertical scaling using the Azure Virtual Machine scale sets:

https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-vertical-scale-reprovision

Vertical scaling does require a VM restart, but if the restart of each VM node is staggered, there will be no noticeable downtime.

The managed Azure SQL database does allow for scaling as well, but it will be a manual process and require a short downtime. Currently, there is no dynamic scaling of the managed Azure SQL database.