GAMESS has a long list of files it uses during a calculation, but my local cluster has very slow local disks. Even worse, the system I am using remotely has no local disks on the compute node and I have to use the remote filesystem to store these files!
Is there a way to reduce the amount of disk files GAMESS uses, or even run the calculations entirely in RAM?
There are some system level options in GAMESS that can help reduce the amount of disk I/O depending on the method being used.
Check the input keywords MODIO and MEM10 in the $SYSTEM control group in the GAMESS manual. These two keywords provide control over storage of the dictionary file in memory, reduction of print statements and file flushing during calculations, and additional GDDI options for FMO calculations.
On large super computers such as some Cray systems, if there are no local disks it is beneficial to store GAMESS files in a RAM disk (e.g. /tmp directory) as well. Otherwise, the I/O to the network parallel filesystem will make the calculations run very slowly.