Following up on the last blog post which discussed the VAAI primitive Block Zero, this post will discuss Full Copy.
Hardware-accelerated Full Copy
The category of VMware operations which Full Copy aids can be described as “data movement”. Cold Migration, Live Migration (Storage VMotion), and cloning are all operations which trigger the Full Copy primitive.
Similar to Block Zero, the concept of Full Copy is to offload the execution of the tasks to the storage system. This reduces load on the host (CPU, Memory usage), SAN (reduction in traffic) and allows the tasks to be executed faster. The following diagrams show a visual presentation of what Full Copy does:
Without the VAAI Full Copy primtive the vSphere host must read from the source virtual machine or template, and write the destination.
With VAAI Full Copy, the host issues a single command and the storage system performs the data “movement”.
I ran a few operations in the lab so I could share some results. This first screenshot was taken from vCenter and it shows what the throughput looked like for two cloning tasks. The first (pointers in blue) was without Full Copy. The second (pointers in red) was with Full Copy.
The next two graphs show the time required to complete tasks. First is a clone of a 40GB virtual machine, the second is a Storage VMotion of 40GB virtual machine running a IOmeter workload simulating SQL IO. In both cases I saw a favorable decrease in the amount of time that it took the task to execute.
So as with Block Zero, Full Copy means VMware tasks are faster and more efficient.