IOStatus

IOstatus is a general term used in computing to describe the status or result of an input/output operation. It encompasses the outcome of an I/O request, including whether the operation succeeded or failed and, in many cases, details such as how many bytes were transferred or which error occurred. The concept helps software, drivers, and systems code handle I/O results in a uniform way, enabling appropriate error handling, retries, or data processing based on the reported status.

In Windows, a closely related concept is the IO_STATUS_BLOCK, a structure used by the kernel and driver interfaces to report the final status of an I/O operation. This block typically contains a status field (often an NTSTATUS value) and an information field that indicates supplementary data such as the number of bytes transferred. The IO_STATUS_BLOCK is part of the broader I/O subsystem that mediates between I/O requests and devices or file systems.

Beyond Windows, IO status appears in various forms across programming environments. High-level languages and libraries commonly return a status or result object that encodes success or failure and, when applicable, the amount of data read or written. In POSIX and similar interfaces, the return value and errno provide equivalent status information for read and write operations, while performance monitoring often tracks IO status to measure throughput, latency, and error rate.

Overall, IOstatus is not a single standard but a general concept: the reported outcome of an I/O operation, with system-specific implementations defining the exact fields and semantics.