1. A method for providing high availability (HA) protection to a virtual machine (VM) executing on an active host, the method comprising: a first processor of the active host initializing HA protection on a running VM at the active host, wherein the initialization of HA protection occurs without stopping an application executing on the active host and while maintaining a connection of the active host, wherein initializing comprises: the first processor synchronizing a disk image of the VM between a disk storage at the active host and a standby host while the VM is running; the first processor and a second processor of the standby host maintaining the synchronization of the disk image of the VM; after initially synchronizing the disk image of the VM by copying the disk image of the VM from the disk storage at the active host to the standby host and while maintaining the synchronization of the disk image of the VM, the first processor synchronizing a memory image of the VM between the active host and the standby host, wherein, after memory synchronization, the memory image of the VM and disk image of the VM are synchronized; once disk synchronization and memory synchronization are completed and the disk image and the memory image of the VM are synchronized, the second processor enabling a dynamic disk barrier process to be applied at a checkpoint time; and at a checkpoint interval time thereinafter, the first processor and the second processor synchronizing the disk image and the memory of the VM between the active host and the standby host for all changes, wherein the standby host controls a synchronization control process at the standby host that utilizes the dynamic disk barrier process to keep the memory and disk images of the VM synchronized at the checkpoint interval time for the VM on the active host and the standby host.