This option uses the CRAY specific ssread/sswrite package to read and write data to and from solid state disk. Solid state disk is assumed and this is the fastest way to more data between solid state disk and memory. The performance is comparable to option ramdrive. All I/O is done in blocks of 512 words and all blocking and buffering is done in iomngr.F and odam.F. On the CRAY YMP, option crayio was sufficient for good performance. On the CRAY T90 it is not. Script run_iomngr executes the driver in iomngr.F to exercise this form of I/O in a simple environment.