Editing Intelligent Peripheral Interface (section)

'''Intelligent Peripheral Interface''' ('''IPI''') was a server-centric storage [[computer bus|interface]] used in the 1980s and early 1990s with an [[International Organization for Standardization|ISO]]-9318 standard.<ref>{{citation |editor-last=Allan|editor-first=Dal|title=ISO/DIS 9318 -- Information Processing Systems -- Intelligent Peripheral Interface|publisher=International Organization for Standardization|publication-date=1988}}</ref> designed for [[mainframe computer]]s from IBM, [[Control Data Corporation]], and [[Unisys]]. It replaced [[Storage Module Device]] (SMD) as the [[hard disk drive interface]] for very large hard disks.<ref name="glass198902">{{Cite magazine |last=Glass |first=Brett |date=February 1989 |title=Hard Disk Interfaces |url=https://archive.org/details/eu_BYTE-1989-02_OCR/page/n350/mode/1up?view=theater |access-date=2024-10-08 |magazine=BYTE |pages=293-297}}</ref>

The idea behind IPI is that the disk drives themselves are as simple as possible, containing only the lowest level control circuitry, while the IPI interface card encapsulates most of the [[disk control]] complexity.  The IPI [[interface card]], as a central point of control, is thus theoretically able to best coordinate accesses to the connected disks, as it "knows" more about the states of the connected disks than would, say, a [[SCSI]] interface.

IPI supports cable lengths up to {{convert|125|m}}.{{r|glass198902}} An IPI-2 bus can provide a [[Bit rate|data transfer rate]] in the vicinity of 6 [[Megabyte|MB]]/[[second|s]].

In practice, the theoretical advantages of IPI over SCSI were often not realized, as they only materialized when several disks were connected to the interface, which could then easily become a bandwidth bottleneck.

IPI systems were often shipped by [[Sun Microsystems]] on original sun4 architecture servers, but the above limitation and reliability problems made them unpopular with customers, and the technology basically disappeared by the second half of the 1990s.