PRMan has the ability to resume interrupted renders. How this works depends on the mode that it's running in. Non-incremental renders to TIFF and OpenEXR images can always be recovered. Incremental renders to OpenEXR images can also be recovered, but only if the checkpointing option was used.

Checkpointing can be found in the rendermanrendersettings node under Rendering → Render → Checkpoint Render

Checkpoint Exit at

You can use this parameter to set a time in hour / minutes / seconds for the renderer to exit.  If a sequence of frames is being rendered, then the renderer will move onto the next frame in the sequence.

Below is an example of the format required

• 60s - this is 60 seconds
• 60m - this is 60 minutes
• 60h - this is 60 hours
• 60d - this is 60 days
  
  

The image grid below demonstrates checkpointing at 1m, 2m, 5m, 10m

Checkpoint Interval

This is a periodic checkpoint. This can be specified with an interval measured either in a number of increments (i.e., passes over the image), or by the elapsed wall clock time. For example, you could ask the renderer to write checkpoints with an interval of 100i, meaning every 100 increments and it will update the images on disk with the state of the render on the 100th, 200th, 300th increment, and so forth.