The I/O supervisor components of OS/2 Version 2.0 are designed to make greater use of advanced I/O devices than previous versions of OS/2. Particular emphasis has been given to the optimization of disk access through the use of the High Performance File System and SCSI devices.
New to OS/2 V2.0 is the Layered Device Driver architecture which enables the device drivers to be developed more easily to support OEM hardware. This interface expedites the development of new DASD and SCSI device support by OEM's by reducing device driver code and complexity. This architecture allows OS/2 to better support a broad range of OEM platforms and devices.
Device drivers are provided with new device help commands to enable drivers to more efficiently use the 32-bit flat memory model and the paging facility for virtual memory management.
A new disk device driver has been defined for use by the High Performance File System, which optimizes access to SCSI devices by allowing request prioritization and making use of the command chaining capabilities of the SCSI adapters. This optimization allows more efficient use of the physical devices. For paging operations where the sequence of read and write operations may be critical, the device driver allows the request optimization to be disabled.