Adaptec 58300 - SAS Storage Controller 300 MBps Installation And User Manual

Also see for 48300: Installation and user guide Datasheet

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Adaptec 58300 - SAS Storage Controller 300 MBps Installation And User Manual Manual pdf 55 page image

Appendix A: Introduction to SAS ● 55Direct-attach ConnectionsIn a direct-attach connection, SAS or SATA disk drives are connected directly to a SAS cardwith SAS cables. One disk drive is attached to one SAS connector with one SAS cable (ormultiple disk drives are attached to one SAS connector with one fan-out cable). The figure onpage 26 shows an example of direct-attach connections.The number of direct-attached disk drives is limited to the number of phys supported by theSAS card. (Note that there may be multiple phys within a single connector. See page 54.)Backplane ConnectionsIn a backplane connection, disk drives and SAS cards are attached to and communicate witheach other through a system backplane. The figure on page 27 shows an example of backplaneconnections.The number of end devices is limited to the number of slots available on the backplane. Forexample, the Adaptec S50 enclosure, which contains an expander, is a backplane connectionthat supports up to 12 SAS or SATA disk drives.Some backplanes support daisy-chain expansion to other backplanes. For example, you candaisy-chain (connect one to the next) up to nine Adaptec S50 enclosures to a single SAS card ina host system.SAS Expander ConnectionsA SAS expander device literally expands the number of end devices that you can connecttogether. Expander devices, typically embedded into a system backplane (see page 27), supportlarge configurations of SAS end devices, including SAS cards and SAS and SATA disk drives.With expander devices, you can build large and complex storage topologies.There are two types of SAS expanders: fanout expanders and edge expanders. Each performs adifferent role in a storage system. (For more information about how SAS expanders work, referto the STA Web site at www.scsita.org.)You can connect up to 128 SAS ports to an edge expander. (A single edge expander cantherefore support up to 128 SAS addresses.)You can connect up to 128 edge expanders to a fanout expander.You can use only one fanout expander in any single SAS domain (a topology of SAS—andpossibly SATA—end devices and expander devices). A single SAS domain can thereforecomprise up to 16,384 SAS ports (and therefore up to 16,384 SAS addresses).