VMware vMotion Special Features – Part 3
VMWARE VMOTION SPECIAL FEATURES – PART 3
Quick Resume & Stun During Page Send
Since the amount of memory available to virtual machines is always growing, VMware must be aware of this and must optimize vMotion for these VMs. Therefore VMware introduced some VMware vMotion Special Features to cover the future needs. Quick Resume is a minimal modification to the vMotion procedure, since the entire memory capacity on the target host is not required until the migration is finished completely.Quick Resume activates the target VM already before the entire memory data has been migrated. The source VM is paused (Stun Mode), but its resources are not freed. In the background, VMware continues to copy the rest of the memory content and allows the target ESX host to access pages on the source ESX host.
As beautiful as this process seems at first glance, it also introduces the possibility of dangerous issues in the case of a hardware crash during theQuick Resume process. In order to circumvent this, VMware uses a file on the central storage that acts as a sort of data buffer so that in the case of a hardware failure the migration process can still be completed. Of course this leads to this form of Quick Resume having a decreased performance, but without this functionality a vMotion process between VMs with a large amount of vRAM would not be possible.
Read the entire article here, VMware vMotion Special Features – Part 3