Appendix A: Introduction to SAS ● 71How are Disk Drives Identified in SAS?In the BIOS and in the management utilities (see Identifying Disk Drives on page 92), diskdrives are identified in the following formats:● CNX:DevY = Device Y is attached to Connector X (see Direct-attach Connections below formore information)● BoxX:SlotX = Enclosure X is attached to a disk drive in Slot X (see Backplane Connectionsbelow for more information)● ExpX:PhyX = Expander X is attached to Phy X (see SAS Expander Connections below formore information)where X is the count number.Note: Devices other than disk drives (CDROM, tape drives, etc...) are listed in order after yoursystem disk drives.In parallel SCSI, XX is the disk drive’s channel number, YY is the target number, and ZZ is thelogical unit number (LUN).What are the SAS Connection Options?You can connect end devices to each other through direct cable connections and throughbackplane connections. When you use one or more expander devices (see page 72), you cancreate large configurations.Direct-attach ConnectionsIn a direct-attach connection, SAS or SATA disk drives are connected directly to a SAS cardwith SAS or mini-SAS cables. One disk drive is attached to one SAS/mini-SAS connector withone SAS/mini-SAS cable (or multiple disk drives are attached to one SAS/mini-SAS connectorwith one fan-out cable). The figure on page 39 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 72.)Backplane ConnectionsIn a backplane connection, disk drives and SAS cards are attached to and communicate witheach other through a system backplane.There are two types of backplane connections, passive and active. When connecting to eitherbackplane, it’s important to properly connect your disk drive LEDs in order to identify diskdrive conditions. See About Your RAID Controller on page 15 for your RAID controller ActivityLED connections and locations.Once you have connected to a backplane, the Adaptec Storage Manager enables you to manageyour disk drives. For more information, refer to the Adaptec Storage Manager User’s Guide onthe Adaptec Storage Manager Installation CD..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.
