The Chaos groups reveals one of the features in store for V-Ray 3.5 service pack: Resumable rendering. V-Ray will allow you to resume incomplete renders where you left off. Perhaps there was a power failure, or you simply stopped the render on your own.
The Resumable rendering feature will roll out first in V-Ray for 3ds Max, and then trickle to other platforms. To use the new feature, all you have to do is turn on “Resumable Rendering” in the VFB settings in the render dialogue. Alternatively, you can pass the -resume=1 option to V-Ray Standalone. You can set a time interval for incremental saves if you are using V-Ray’s progressive rendering feature.
The Chaos Group will support two types of resumable rending in V-Ray, bucket and progressive. There are some things to consider when discussing resumable rendering, which The Chaos Group have laid out in this article. There are also some use cases to go over.
Seems like a nice feature to have, if you find yourself stopping rendering a lot, for what ever reason.