## Storage Device Driver Reference

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### Disk Device Driver Architecture

Driver architecture centers around the need to provide fast, efficient services to a file system in a paged environment. In addition, consideration for the needs of a network file server has influenced aspects of the design; however, the requirements are identical in a local-only or workstation environment (that is, a direct, asynchronous, zero-overhead interface between the file system and the supporting physical disk device drivers).

In the OS/2 operating system, a physical disk device driver receives requests for service through a strategy routine at task time in the context of the requestor (an OS/2 thread). The thread of control is also obtained, in the context of interrupts generated by the disk controller, at the physical device driver interrupt routine. In the extended architecture, a second strategy routine is introduced, which can be called directly by File System Drivers (FSDs) at task time or in the context of an arbitrary interrupt. This yields a set of new requirements.