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Is the reason why Serial-attached SCSI (SAS) is experiencing increased sucess in the
marketplace. Largely, because SAS incorporates tried and testet technologies such as
SCSI and the XAUI physical layer. So far, SAS is proving to be a good candidate for
implementation and there is a growing degree of interest, as new reasons to invest in
SAS emerge.
Serial Attached SCSI (SAS), offers more-flexible storage solutions . Although SAS was not the first attempt to serialize the SCSI protocol, it is the first standard specification to provide an interconnect mechanism for both SCSI and Serial ATA (SATA). By accomplishing this, SAS meets both enterprise and midrange/nearline storage requirements at relatively low costs with flexible storage architectures.
Serial Attached SCSI (SAS), offers more-flexible storage solutions . Although SAS was not the first attempt to serialize the SCSI protocol, it is the first standard specification to provide an interconnect mechanism for both SCSI and Serial ATA (SATA). By accomplishing this, SAS meets both enterprise and midrange/nearline storage requirements at relatively low costs with flexible storage architectures.
SAS and serial ATA each share a out-of-band protocol (OOB) used to let end nodes identify the SAS or SATA devices and run
initialization. SAS uses OOB for initialization and interoperability with SATA devices. At the encoding layer, SAS uses 8b10b
encoding to create transmission characters and primitives from bits. This encoding method is used by both Fibre Channel and
Gigabit Ethernet. When using such a tried and true encoding method, SAS ensures that there won't be any surprises at this layer
when the technology is deployed.
Serialization of the SCSI interface overcomes the physical and functional limitations of the parallel interface. Over time, increased bandwidth requirements and challenges presented by clock skew and power consumption ultimately prevented SCSI from moving beyond the Ultra320 specification. Serialization faced down the parallel interface limitations while significantly reducing power consumption. SAS basically leverages technologies prevalent in other serial interfaces, including SATA, Gigabit Ethernet, and Fibre Channel.
A typical Serial Attached SCSI RAID or JBOD solution consists of the following basic components: An Initiator, a Taget, a Service Delivery Subsystem, Expanders and a SAS Domain & WWN (World Wide Name)
An Initiator is a device that originates device service and task management requests to be processed by a target device and receives responses for the same requests from other target devices. Initiators may be provided as an on-board component on the motherboard (as is the case with many server-oriented motherboards) or as an add-on host bus adapter.
A Target is a device containing logical units and target ports that receives device service and task management requests for processing and sends responses for the same requests to initiator devices. A target device could be a hard disk or a disk array system.
A Service Delivery Subsystem is the part of an I/O system that transmits information between an initiator and a target. Typically cables connecting an initiator and target with or without expanders and backplanes constitute a service delivery subsystem.
Expanders are devices that are part of a service delivery subsystem and facilitate communication between SAS devices. It facilitates connection of multiple SAS End devices to a single initiator port.
SAS Domain & WWN (World Wide Name) A "SAS Domain" is an I/O system consisting of a set of SAS devices that communicate with one another by means of a service delivery subsystem. Each SAS device in a SAS domain has a globally unique identifier assigned by the device manufacturer (similar to an Ethernet device's MAC address) called a World Wide Name (aka SAS address). The WWN uniquely identifies the device in the SAS domain just as a SCSI ID identifies a device in a parallel SCSI bus. A SAS domain may contain up to a total of 16,256 devices
A functional SAS based RAID solution offers RAID level support for levels 0, 1 (0+1), 3, 5, 6, 10, 30, 50, 60, and NRAID . For a detailed explanation of what each RAID level is please visit our RAID Levels Definitions page. Our DSS EONSTOR SAS RAID Solutions can scale up to 80 hdd's and reach enterprise level capacity points. To find out how Data Storage Systems, Inc. can implement a SAS RAID with a SAS Domain into your data center, please contact our sales and support staff by calling (800-519-4737) or e-Mail: sales@datastoragesys.com. Our DSS RAID Systems are custom configured, tested and we offer installation and on-site support options as well. Please click here to see our complete line of DSS SAS based RAID Solutions.
Serialization of the SCSI interface overcomes the physical and functional limitations of the parallel interface. Over time, increased bandwidth requirements and challenges presented by clock skew and power consumption ultimately prevented SCSI from moving beyond the Ultra320 specification. Serialization faced down the parallel interface limitations while significantly reducing power consumption. SAS basically leverages technologies prevalent in other serial interfaces, including SATA, Gigabit Ethernet, and Fibre Channel.
A typical Serial Attached SCSI RAID or JBOD solution consists of the following basic components: An Initiator, a Taget, a Service Delivery Subsystem, Expanders and a SAS Domain & WWN (World Wide Name)
An Initiator is a device that originates device service and task management requests to be processed by a target device and receives responses for the same requests from other target devices. Initiators may be provided as an on-board component on the motherboard (as is the case with many server-oriented motherboards) or as an add-on host bus adapter.
A Target is a device containing logical units and target ports that receives device service and task management requests for processing and sends responses for the same requests to initiator devices. A target device could be a hard disk or a disk array system.
A Service Delivery Subsystem is the part of an I/O system that transmits information between an initiator and a target. Typically cables connecting an initiator and target with or without expanders and backplanes constitute a service delivery subsystem.
Expanders are devices that are part of a service delivery subsystem and facilitate communication between SAS devices. It facilitates connection of multiple SAS End devices to a single initiator port.
SAS Domain & WWN (World Wide Name) A "SAS Domain" is an I/O system consisting of a set of SAS devices that communicate with one another by means of a service delivery subsystem. Each SAS device in a SAS domain has a globally unique identifier assigned by the device manufacturer (similar to an Ethernet device's MAC address) called a World Wide Name (aka SAS address). The WWN uniquely identifies the device in the SAS domain just as a SCSI ID identifies a device in a parallel SCSI bus. A SAS domain may contain up to a total of 16,256 devices
A functional SAS based RAID solution offers RAID level support for levels 0, 1 (0+1), 3, 5, 6, 10, 30, 50, 60, and NRAID . For a detailed explanation of what each RAID level is please visit our RAID Levels Definitions page. Our DSS EONSTOR SAS RAID Solutions can scale up to 80 hdd's and reach enterprise level capacity points. To find out how Data Storage Systems, Inc. can implement a SAS RAID with a SAS Domain into your data center, please contact our sales and support staff by calling (800-519-4737) or e-Mail: sales@datastoragesys.com. Our DSS RAID Systems are custom configured, tested and we offer installation and on-site support options as well. Please click here to see our complete line of DSS SAS based RAID Solutions.
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