Adaptec 6805Q 2270700-R User Manual

Appendix A: Introduction to SAS

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How are Disk Drives Identified in SAS?

In the BIOS and in the management utilities (see 

), disk 

drives are identified in the following formats:

●

CNX:DevY = Device Y is attached to Connector X (see 

 below for 

more information)

●

BoxX:SlotX = Enclosure X is attached to a disk drive in Slot X (see 

 

below for more information)

●

ExpX:PhyX = Expander X is attached to Phy X (see 

 below for 

more information)

where X is the count number.

Note: 

Devices other than disk drives (CDROM, tape drives, etc...) are listed in order after your 

system disk drives.

In parallel SCSI, XX is the disk drive’s channel number, YY is the target number, and ZZ is the 
logical unit number (LUN).

What are the SAS Connection Options?

You can connect end devices to each other through direct cable connections and through 
backplane connections. When you use one or more expander devices (see 

), you can 

create large configurations.

Direct-attach Connections

In a direct-attach connection, SAS or SATA disk drives are connected directly to a SAS card 
with SAS or mini-SAS cables. One disk drive is attached to one SAS/mini-SAS connector with 
one SAS/mini-SAS cable (or multiple disk drives are attached to one SAS/mini-SAS connector 
with one fan-out cable). The figure on 

 shows an example of direct-attach connections.

The number of direct-attached disk drives is limited to the number of phys supported by the 
SAS card. (Note that there may be multiple phys within a single connector. See 

.)

Backplane Connections

In a backplane connection, disk drives and SAS cards are attached to and communicate with 
each other through a system backplane. 

There are two types of backplane connections, passive and active. When connecting to either 
backplane, it’s important to properly connect your disk drive LEDs in order to identify disk 
drive conditions. See 

 for your RAID controller Activity 

LED connections and locations.

Once you have connected to a backplane, use Adaptec Storage Manager to manage your disk 
drives. For more information, refer to the Adaptec Storage Manager User’s Guide on the Adaptec 
Installation DVD.

.The number of end devices is limited to the number of slots available on the backplane. For 
example, the Adaptec S50 enclosure, which contains an expander, is a backplane connection 
that supports up to 12 SAS or SATA disk drives.