4.1 SCM_IOBUFFERSIZE

Most programs within the ADF pacakge use the KF IO system. This is coupled to a facility to store (parts of) files in memory, if you have enough memory available. Thus, the programs will cache the IO data instead of the operating system, and reduce the amount of IO significantly.

It depends on your operating system and hardware if you can benefit from this scheme. The default is a small buffer (8 MB), which has only a small performance benefit. Sometimes this is all you can get, but in some cases you can have a major performance improvement by making this buffer much larger, for example 128 MB or 256 MB. You do this by setting the SCM_IOBUFFERSIZE environment variable.

Please try for yourself, with your typical calculation on your production machine to find out the optimal value for your situation.