How the platform scales VMs

To scale out, the platform does not deploy VMs that are undeployed in the scaling group. To clone the base VM, the platform will do the following:

1. Create disks using the following:
   
   1. Copies of content of disks from the VM template
   2. Empty disks or volumes for each additional disk used in the VM
   3. Disk controllers used in the VM
2. Apply ALL configuration used in the VM, for example:
   
   1. CPU and RAM
   2. Network connections of the same type (e.g. private network)
   3. Assignment of firewall policies and attachment to load balancers
   4. Chef recipes, backups, cloud-init, variables, and so on
   5. Metrics. The group of metrics from clone VMs and the base VM (if it is deployed) can activate alarms in the base VM, even if it is not deployed
   6. Exception – Alarms: the scaling group has only one set of alarms in the base VM

To scale in,  Abiquo currently selects the VMs to delete or undeploy using first in, first out (FIFO). The platform deletes and undeploys VMs without requesting user confirmation when there are disks that are not stored in the Apps library (ISO configuration drive or additional hard disk).