Adaptec 1220SA Manual De Usuario

Appendix A: Introduction to SAS

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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 
controller with SAS cables. One disk drive is connected to one SAS connector with one SAS 
cable or multiple disk drives are connected to one SAS connector with one fan-out cable. The 
figure on 

 shows an example of direct-attach connections.

The number of direct-connected disk drives is limited to the number of phys supported by the 
SAS controller. 

Note: 

There may be multiple phys within a single connector. See 

.

Backplane Connections

In a backplane connection, disk drives and SAS controllers are connected to and communicate 
with each other through a system backplane. The figure on 

 shows an example of 

backplane connections.

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.

When connecting to a backplane, the Adaptec Storage Manager enables you to manage your 
system disk drives, see 

.

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.

Some backplanes support daisy-chain expansion to other backplanes. For example, you can 
daisy-chain up to nine Adaptec S50 enclosures to a single SAS controller in a host system.

SAS Expander Connections

A SAS expander device literally expands the number of end devices that you can connect 
together. Expander devices, typically embedded into a system backplane (see 

), support 

large configurations of SAS end devices, including SAS controllers 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 a 
different role in a storage system. (For more information about how SAS expanders work, refer 
to the STA Web site at 

You can connect up to 128 SAS ports to an edge expander. (A single edge expander can 
therefore support up to 128 SAS addresses.)