|
The Digital Storage Systems Interconnect (DSSI) is a bus developed by Digital Equipment Corporation for connecting storage devices and clustering VAX systems and support was extended to MIPS based DECsystem and later to Alpha processor based AlphaServer systems. It was introduced in 1988 and has a bandwidth of 32 Mbit/s and was typically limited to a length of 25 meters. DSSI peripherals could be distinguished from narrow SCSI devices by their characteristic five conductor power connector featuring an extra lead intended for Battery/UPS connection to power critical components in the event of a power failure. == Characteristics == The major characteristics of the DSSI bus are: * Eight-bit data path * Up to eight nodes on the bus including variable numbers of initiators and targets * Distributed arbitration * Peak bandwidth of 4 megabytes per second * All systems connected to the same DSSI bus must have a common power/ground. * "The Q-Bus 5-Enclosure Rule": For Q-bus VMScluster configurations, a maximum of five enclosures, _excluding_ SF200/210s, can be configured on a single DSSI bus. Note that only _one_ (1) SF100 is allowed on any DSSI bus. * "The VAX 6000 Cabinet Rule": For a VAX 6000 DSSI VMScluster system, a maximum of two or three VAX 6000 systems and one storage cabinet, typically an SF200 or SF210, can be configured on a single DSSI bus. * Maximum DSSI bus length cannot exceed 27 meters (89 feet) and ground offset voltage cannot exceed 30mv (dc) or 10.5mv (rms). Bus Length Allowable Offset Meters/Feet (DC) (AC) ----------- ---------------- up to 20/65 200mv 70mv (rms) 20-25/65-82 40mv 14mv (rms) VAX6000 QUAD-Host--> 27/89 30mv 10.5mv (rms) VAX7000 VAX10000 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Digital Storage Systems Interconnect」の詳細全文を読む スポンサード リンク
|