Adaptec SCSI 58300 Installation And User Manual

Also see for 44300: Installation and user guide Installation and user guide User guide

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Adaptec SCSI 58300 Installation And User Manual Manual pdf 59 page image

Appendix A: Introduction to SAS ● 59SAS controller port options vary. A SAS controller with four phys could be configured with onewide port, with two wide ports that comprise two phys, or with four narrow ports eachcontaining one phy. (A wide port with four phys is referred to as a 4-wide or 4x port.)What’s a SAS Address?Each SAS port is identified with a unique SAS address, which is shared by all phys on that port.For example, a SAS disk drive might have two narrow ports. Each port has one unique SASaddress. The single phy in each port uses its port’s SAS address.In another example, a SAS device might have one 4-wide port. That port has one SAS address,which is shared by all four phys in the port.Unlike SCSI devices and SCSI IDs, SAS devices self-configure their SAS addresses. Userintervention is not required to set SAS addresses, and SAS addresses cannot be modified.What’s a SAS Connector?A SAS or mini-SAS connector is the physical plug or receptacle that you see on a SAS device. Itsupports the power and signal line cable. It’s what you plug a SAS cable into, or the end of theSAS cable that’s being plugged in.A connector is what forms physical links between phys. Some SAS connectors can supportmultiple links. The number of links a SAS connector can support is referred to as its width.Narrow connectors support a single link; wide connectors support up to four links.A single SAS device may have one or more connectors. You can use a single SAS connector tointer-link more than two SAS devices. For example, in the figure on page 58, the 4-wideinternal SAS connector forms links with four independent disk drives.Mini-SAS connectors support both internal and external SAS connections. The mini-SASconnectors are smaller than the standard SAS internal and external connectors. Mini-SASconnectors support single and multilinks with the ability to scale to future speed needs.What do SAS Cables Look Like?Internal SAS cables are narrower than internal parallel SCSI cables. The connectors vary in sizedepending on the number of links they support, from single link connectors to 4-wide (orlarger) connectors. Internal fan-out cables let you connect four disk drives to a single 4-wideconnector.For an example of some internal SAS or mini-SAS cables and an external SAS cable, seeSelecting SAS Cables on page 27.How are Disk Drives Identified in SAS?In the BIOS and in the management utilities, disk drives are identified with numbers in thisformat:XX:YY:ZZwhere XX is the disk drive count number, YY is the enclosure number, and ZZ is the slotnumber (within the enclosure). If the disk drive is not installed in an enclosure, a doubledashes (--) appear instead of YY and ZZ (for instance, 01:--:--).