Serial Storage Architecture

Serial Storage Architecture

Serial Storage Architecture (SSA) is a serial transport protocol used to attach disk drives to servers. It was invented by Ian Judd of IBM in 1990. IBM produced a number of successful products based upon this standard before it was overtaken by the more widely adopted Fibre Channel protocol.

SSA was promoted as an open standard by the SSA Industry Association. A number of vendors including IBM, Pathlight Technologies and Viacom produced products based on SSA. It was also adopted as an ANSI X3T10.1 standard. SSA devices are logically SCSI devices and conform to all of the SCSI command protocols.

SSA provides data protection for critical applications by helping to ensure that a single cable failure will not prevent access to data. All the components in a typical SSA subsystem are connected by bi-directional cabling. Data sent from the adaptor can travel in either direction around the loop to its destination. SSA detects interruptions in the loop and automatically reconfigures the system to help maintain connection while a link is restored.

Up to 192 hot swappable hard disk drives can be supported per system. Drives can be designated for use by an array in the event of hardware failure. Up to 32 separate RAID arrays can be supported per adaptor, and arrays can be mirrored across servers to provide cost-effective protection for critical applications. Furthermore, arrays can be sited up to 25 metres apart - connected by thin, low-cost copper cables - allowing subsystems to be located in secure, convenient locations, far from the server itself.

With its inherent resiliency and ease of use, SSA is deployed in server/RAID environments, where it is capable of providing for up to 80 Mbyte/s of data throughput, with sustained data rates as high as 60 Mbytes/s in non-RAID mode and 35 Mbytes/s in RAID mode.

Link characteristics

The copper cables used in SSA configurations are round bundles of two or four twisted pairs, up to 25 metres long and terminated with 9-pin micro-D connectors. Impedances are 75 ohm single-ended, and 150 ohm differential. For longer-distance connections, it is possible to use fiber-optic cables up to 10 km (6 mi) in length. Signals are differential TTL. The transmission capacity is 20 megabytes per second in each direction per channel, with up to two channels per cable. The transport layer protocol is non return to zero, with 8B/10B encoding (10 bits per character). Higher protocol layers were based on the SCSI-3 standard.

ee also

*List of device bandwidths

Products which used SSA

*IBM 7133 Disk expansion enclosures
*IBM 2105 Versatile Storage Server (VSS)
*IBM 2105 Enterprise Storage Server (ESS)


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Serial Storage Architecture — (SSA) beschreibt eine Methode, um Speichersubsysteme (also Massenspeicher wie Jukeboxen und Disk Arrays) hochperformant an Rechner zu koppeln, insbesondere an Server Systeme oder Großcomputer. SSA ist ein mittlerweile überholter Standard und… …   Deutsch Wikipedia

  • Serial Storage Architecture — Serial Storage Architecture,   SSA …   Universal-Lexikon

  • Serial Storage Architecture —    Abbreviated SSA. A high performance serial interface, originally developed by IBM, used to connect peripherals, such as scanners, disk drives, optical disks, and printers, to workstations or servers. A typical SSA interface has two ports with… …   Dictionary of networking

  • serial communications —    The transmission of information from computer to computer or from computer to peripheral device one bit at a time.    Serial communications can be synchronous and controlled by a clock, or they can be asynchronous and coordinated by start and… …   Dictionary of networking

  • Serial Attached SCSI — (SAS) is a data transfer technology designed to move data to and from computer storage devices such as hard drives and tape drives. It is a point to point serial protocol that replaces the parallel SCSI bus technology that first appeared in the… …   Wikipedia

  • Serial ATA — SATA redirects here. For other uses, see SATA (disambiguation). Serial ATA (SATA) From top to bottom, SATA Certification Logo, SATA cable, and two first generation (1.5 Gbit/s) SATA data connectors on a …   Wikipedia

  • IBM Enterprise Storage Server — The IBM Enterprise Storage Server (ESS) or the Shark is an enterprise storage array from IBM. History Originally, in 1998 IBM released the IBM 2105 Versatile Storage Server (VSS). It did not meet commercial success and the successor came in 1999… …   Wikipedia

  • CompactPCI Serial — is a new industrial standard for modular computer systems. It is based on the established PICMG 2.0 CompactPCI standard[1], which uses the parallel PCI bus for communication among a system s card components. In contrast to this, CompactPCI Serial …   Wikipedia

  • Industry Standard Architecture — For other uses of ISA , see Isa (disambiguation). ISA Industry Standard Architecture Five 16 bit and one 8 bit ISA slots on a motherboard Year created 1981 Created by …   Wikipedia

  • Buffalo network-attached storage series — Infobox Information appliance name = Buffalo network attached storage series caption = The Kuro Box Pro manufacturer = Melco type = Network attached storage connectivity = 100BASE T, 1000BASE T os = Linux cpu = PowerPC, MIPSel, ARM The Buffalo… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”