The server is attempting to save a large volume of small files to one of our disk arrays but the array is not designed for such small files so it has fallen behind. When this happens the operating system holds these files in Memory (RAM) until the disk isn't overloaded.
Now usually this isn't a problem but we've been rendering our map for almost three days now and it's still not done. These millions of tiny image files have now filled our RAM to 99% and the disk is still overloaded. It has a huge backlog of about 10GB of data to write.
I've paused the map render for the time being to allow the disk array to catch up but it's not really making any difference for some reason. I'm working on the problem though and I hope to have it resolved soon.
Here is a screenshot of our current memory usage:
