Firmware And Software; Serial Tunneling Protocol (Stp); Spc-3 Target Port Group Commands - HP 381513-B21 - Smart Array P800 Controller RAID Technology Brief

Redundancy in enterprise storage networks using dual domain sas configurations

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A computing cluster must have a dedicated cluster interconnect to which all cluster members are

connected. This interconnect serves as a private communication channel between cluster members

and HP Smart Array controllers directing data traffic on existing domains

The cluster interconnect is normally used for five high-level functions:

• Cluster Executive components

• Cluster I/O

• Cluster Networking

• Reliable Datagrams

• Application-specific traffic.

Firmware and Software

A storage network with redundant paths must employ protocols and command sets that provide a

basis for communication and retrieval of information about the state of each pathway and all of the

devices on those pathways. Further, these protocols and command sets must have the ability to direct

traffic by controlling switches and links to dictate "active and inactive" pathways.

STP allows a SAS host to communicate directly with SATA Targets (SATA devices addressable in a

SAS Expander topology). When data is directed to a SATA drive connected to a SAS backplane

through an edge expander, an STP connection immediately opens to enable SATA frames to pass

through the connection to the drive. STP operates transparently in the storage network with virtually no

impact on system throughput.

Within the dual-domain SAS network of available paths between initiator and target devices, a

command set must exist to control the switches and links causing these paths to be set in active,

inactive or standby states. The SPC-3 Target port group commands serve those functions.

A target port group is a set of target ports that are always in the same state (for instance, a multi-

ported controller card).

A "logical unit group" is a set of logical units (LUs) whose target port groups are always in the same

state. For example, in an active-optimized/active-non-optimized RAID controller, one controller may

be optimized for one set of LUs and the other for the rest of the LUs.

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