Appendix A: Introduction to SAS 62

You can connect up to 128 edge expanders to a fanout expander.

You can use only one fanout expander in any single SAS domain (a topology of SAS—and possibly SATA—end devices and expander devices). A single SAS domain can therefore comprise up to 16,384 SAS ports (and therefore up to 16,384 SAS addresses).

The following figure illustrates (in very basic terms) a SAS domain and shows how SAS controllers, SAS and SATA disk drives, and expander devices can fit together in a large data storage topology.

 

SAS Domain

SAS

SATA

Disk Drives

Disk Drives

SAS

SATA

SATA

Edge

SAS Card

Expander

Edge

Expander

Edge

Expander

Disk Drives

SATA SAS

Fanout Expander

SAS Card

Edge Expander

Disk Drives

SATA

 

SAS Card

Expander

SATA

Disk Drives

 

SAS SATA

SAS SATA

Disk Drives

Disk Drives

Edge

SAS

How is SAS Different from Parallel SCSI?

In summary, although SAS and parallel SCSI use the SCSI command set, how they move data from one place to another is very different. To support point-to-point serial data transport, SAS introduces new types of connectors, cables, connection options, and terminology.

Generally speaking, SAS is faster and more flexible than parallel SCSI, and provides more options for building your storage space. SAS lets you mix SAS and SATA disk drives together, and lets you connect many, many more devices.

The following table describes many of the main differences between the two interfaces.

Parallel SCSI

Parallel interface

Maximum speed 320 MB/sec shared by all devices on the bus

Supports SCSI devices only

Up to 16 devices per SCSI channel

Supports single-port devices only

Uses SCSI IDs to differentiate between devices connected to the same adapter

Serial Attached SCSI

Serial interface

Maximum speed 600 MB/sec per phy when in full-duplex mode

Supports SATA and SAS disk drives simultaneously

More than 128 disk drives per SAS controller, using an expander (see page 61)

Supports single- and dual-port devices

Uses unique SAS addresses to differentiate between devices

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Adaptec 48300, 58300, 44300, 1220SA, 1420SA, 1225SA, 1430SA manual How is SAS Different from Parallel SCSI?, SAS Domain

1430SA, 1225SA, 1420SA, 1220SA, 48300 specifications

Adaptec, a prominent name in the world of storage solutions, offers a diverse array of RAID controller cards aimed at enhancing data storage and management in both consumer and enterprise markets. Among its acclaimed products are the Adaptec 1220SA, 1430SA, 44300, 1225SA, and 1420SA. These cards ensure increased data protection, improved performance, and greater scalability.

The Adaptec 1220SA is a robust SATA RAID controller designed for small to medium-sized businesses. It supports RAID levels 0, 1, 1E, 5, and 10, providing flexibility for users to optimize data redundancy and performance. With the capability of handling up to four SATA drives, it guarantees an efficient and reliable setup while minimizing potential data loss. The controller also features an intuitive web-based management interface, making it easier to administer and configure.

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