Parallel pixmap image storage and retrieval

Professionals in various fields such as medical imaging, biology and civil engineering require rapid access to huge amounts of uncompressed pixmap image data. In order to fulfil these requirements, a parallel image server architecture is proposed, based on arrays of intelligent disk nodes, each disk node being composed of one processor and one disk. Pixmap image data is partitioned into rectangular extents, whose size and distribution among disk nodes minimize overall image access times. Disk node processors are responsible for maintaining both the data structure associated with their image file extents and an extent cache offering fast access to recently used data. Disk node processors may also be used for applying image processing operations to locally retrieved image parts. This contribution introduces the concept of an image oriented file system, where the file system is aware of image size, extent size and extent distribution. The performance of the proposed transputer-based multiprocessor-multidisk image server is compared with the performance of an ideal single processor disk array system having an infinite bandwidth between the disks and the processor's memory