The most likely situation is that you've filled your disk up, or run out of quota. It can't open the log file because it can't write to the directory, probably because it is full.
The "E72: Close error on swap file" is an error message from vim (do a google search), again caused by the fact that the swap file that vim uses (a dot file in the same directory as the file) can't be created. It's nothing to do with /proc/swap. Not sure what -1 means, but that's totally irrelevant - it's nothing to do with the OS Swap.
In reply to Andrew Beckett:
You are right. It was because the disk quota was exceeded. Once I made more room in my account, simulation is running again.
Today I got another error message, which is shown below:
ERROR (ADE-3036): Errors encountered during simulation. The simulator run log has not been generated.
Possible cause could be an invalid command line option for the version of the simulator
you are running. Choose Setup->Environment and verify that the command line options
specified in the userCmdLineOption field are supported for the simulator.
Alternatively, run the simulator standalone using the runSimulation file in the netlist
directory to know the exact cause of the error.
What does this really mean? This simulation was correct and running fine previously. Today something is not right.
In reply to apple419: