IBM 9008-22L Site And Hardware Planning

Also see for 9008-22L: Manual Manual Manual Manual Manual

Figure 37. Cable management bracketPlanning for serial-attached SCSI cablesSerial-attached SCSI (SAS) cables provide serial communication for transfer of data for directly attacheddevices, such as hard disk drives, solid-state drives, and CD-ROM drives.SAS cable overviewSerial-attached SCSI (SAS) is an evolution of the parallel SCSI device interface into a serial point-to-pointinterface. SAS physical links are a set of four wires that are used as two differential signal pairs. Onedifferential signal transmits in one direction while the other differential signal transmits in the oppositedirection. Data might be transmitted in both directions simultaneously. SAS physical links are contained inports. A port contains one or more SAS physical links. A port is a wide port if there are more than one SASphysical link in the port. Wide ports are designed to enhance performance and provide redundancy incase an individual SAS physical link fail.There are two types of SAS connectors, mini SAS and mini SAS high density (HD). High-density cables aretypically needed to support 6 Gb/s SAS.Each SAS cable contains four SAS physical links that are typically organized into either a single 4x SASport or two 2x SAS ports. Each end of the cable uses a mini SAS or mini SAS HD 4x connector. Review thefollowing design and installation criteria before you install SAS cables:• Only specific cabling configurations are supported. Many configurations can be constructed that are notsupported and will either not function correctly or generates errors. See “SAS cabling configurations” onpage 116 for figures of the supported cabling configurations.• Each mini-SAS 4x connector is keyed to help prevent cabling an unsupported configuration.• HD SAS cables have a key that prevents the cable retention from latching if the cable is orientedincorrectly. HD SAS cables slide in easily and latch correctly if they are inserted with the blue releasetab on the right side of the card connector.• Each cable end has a label that graphically describes the correct component port to which it isconnected, such as:– SAS adapter– Expansion drawer– System external SAS port– Internal SAS disk slots connection.Site and hardware planning 111