Asynchronous I/O architecture For VM/370
Original Publication Date: 1979-Nov-01
Included in the Prior Art Database: 2005-Feb-20
Currently, VM/370 supports the IBM System/370 I/O architected START I/O (SIO) and START I/O FAST (SIOF) interface and the totally synchronous DIAGNOSE I/O interface. With SIO, the virtual machine is suspended until the real SIO is issued to the real device, and in the case of DIAGNOSE, the virtual machine is suspended until the I/O is complete. If the virtual machine is accessing a mini-disk which resides with other mini disks on the real DASD (direct-access storage device), this duration of suspension can be significant as the device may be busy servicing requests from other virtual machines.