HP 418800-B21 Redundancy in enterprise storage networks using dual domain SAS - Page 14

Firmware and Software

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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. Serial Tunneling Protocol (STP) 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. SPC-3 Target port group commands 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 multiported 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. 14

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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.
Serial Tunneling Protocol (STP)
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.
SPC-3 Target port group commands
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.
14