System for completely transferring data from disk having low rate to buffer and transferring data from buffer to computer through channel having higher rate concurrently

摘要

A channel attached peripheral system is described which provides optimized data transfer when the channel has a higher data rate than the data source in the peripheral system. When a read request is received on the channel for data from the data source, the peripheral system estimates a source time as the time required to transfer the data from the data source into a buffer in the RAM and estimates a channel time as the time required to transfer of the units of data from the buffer to the computer over the channel. A channel reconnection time is determined. The transfer of the units of data from the data source into a buffer is initiated as soon as possible after the read request is received, but the transfer of data on the channel is delayed and commences in parallel with transfer of the units of data from the data source into the buffer, when the channel reconnection time has elapsed or when the time surrogate such as a number of cells has been transferred into the buffer.