Parallel I/O, in the context of a computer, means the performance of multiple input/output operations at the same time, for instance simultaneously outputs to storage devices and display devices. [1] It is a fundamental feature of operating systems. [2]
One particular instance is parallel writing of data to disk; when file data is spread across multiple disks, for example in a RAID array, one can store multiple parts of the data at the same time, thereby achieving higher write speeds than with a single device. [3] [4]
Other ways of parallel access to data include: Parallel Virtual File System, Lustre, GFS etc.
It is used for scientific computing and not for databases. It breaks up support into multiple layers including High level I/O library, Middleware layer and Parallel file system. [5] Parallel File System manages the single view, maintains logical space and provides access to data files. [6]
A single file may be stripped across one or more object storage target, which increases the bandwidth while accessing the file and available disk space. [7] The caches are larger in Parallel I/O and shared through distributed memory systems. [8] [9] [10] [11]
Companies have been running Parallel I/O on their servers to achieve results with regard to price and performance. Parallel processing is especially critical for scientific calculations where applications are not only CPU but also are I/O bound. [12]