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Chapter 1 Product Overview
This chapter provides an overview of the Sun StorageTek Traffic Manager
software, and covers the following topics:
About
Sun StorageTek Traffic Manager
The Sun StorageTek Traffic Manager software enables multipathing connections
for Sun Solaris 10 OS hosts. Multipathing provides higher availability
for storage devices through the use of multiple access paths. Fibre Channel
(FC), Serial Attached SCSI (SAS), and Internet Small Computer Storage Interface
(iSCSI) protocols are supported.
The Sun StorageTek Traffic Manager software resides on the host and
identifies the storage devices on your SAN or SAS Domain. The software enables
you to attach Fibre Channel storage in either loop, fabric, or point-to-point
mode. The software provides a common interface for managing both Fibre Channel
and SAS storage.
For information on how to configure targets and initiators in preparation
for multipathing, see the following:
Software Features
The Sun StorageTek Traffic Manager software enables multipathing connections
for the Sun Solaris 10 OS hosts, with the following software features:
Fibre Channel Software Features
The
Sun StorageTek Traffic Manager software provides the following key features:
-
Dynamic Storage Discovery – The software automatically
recognizes devices and any modifications made to device configurations. This
feature makes devices available to the system without requiring you to reboot
or manually change information in configuration files.
-
Persistent Device Naming – Devices that are configured
within the software maintain their device naming through reboots or reconfiguration.
The only exception to this policy are tape devices found in /dev/rmt that
will not change unless they are removed, and then regenerated at a later date.
-
Fibre Channel
Arbitrated Loop (FCAL) Support – OpenBootTM PROM
(OBP) commands that are used on servers can access FCAL attached
storage for scanning the FC loop.
-
Fabric Booting –
The Solaris OS supports booting from fabric devices as well as non-fabric
Fibre Channel devices. Fabric topologies with Fibre Channel switches provide
higher speed, more connections, and port isolation.
-
FC-HBA Library – What was previously known as the Storage
Networking Industry Association Fibre Channel host bus adapter (SNIA
FC-HBA) library is now known as the FC-HBA library. The FC-HBA library application
programming interface (API) enables management of FC HBAs and provides a standards-based
interface for other applications (such as Sun StorEdgeTM Enterprise
Storage Manager) that can be used to gather information about FC HBAs.
Man pages for common FC-HBA APIs are included in the Solaris
10 OS in libhbaapi(3LIB). For additional information about FC specifications, refer to http://www.t11.org.
SAS Software Features
-
Dynamic Storage Discovery – The Solaris OS Storage Multipathing
software automatically recognizes devices and any modifications made to device
configurations. This makes devices available to the system without requiring
you to reboot or manually change information in configuration files.
-
Persistent Device Naming – Dynamic Storage Discovery
Devices that are configured within the Solaris OS Storage Multipathing software
maintain their device naming through reboots or reconfiguration.
Multipathing Software Features
The Solaris
10 OS contains the Sun StorageTek Traffic Manager
software. The software is enabled by default for x86-based platforms and optional
for SPARC-based platforms. The software contains the following features:
-
Path management –
The Sun StorageTek Traffic Manager software dynamically manages the paths
to any storage devices it supports. The addition or removal of paths to a
device is done automatically when a path is brought online or removed from
a service. This feature enables hosts configured with the software to begin
with a single path to a device and add more host controllers, increasing bandwidth
and RAS, without changing device names or modifying applications. Sun storage
does not require configuration files to manage or databases to keep current.
For storage other than Sun, contact your storage vendor for methods to enable
support and to ensure it is qualified with the Sun StorageTek Traffic Manager
software.
-
Single Device Instances –
Unlike other multipathing solutions, the Sun StorageTek Traffic Manager software
is fully integrated with the Solaris 10 OS. The software displays multipath devices
as single device instances instead of as one device, or device link, per path.
This feature reduces the cost of managing complex storage architectures utilities
such as format(1M) or Sun
Solaris OS Volume Manager, to “see” one representation of a storage device instead
of a separate device for each path.
-
Failover support –
Implementing higher levels of RAS requires redundant host connectivity to
storage devices. The Sun StorageTek Traffic Manager software manages the failure
of storage paths while maintaining host I/O connectivity through available
secondary paths.
-
Symmetrical/Asymmetrical device support–
The Sun StorageTek Traffic Manager software supports the following disk storage
devices:
-
All Sun disk storage, both symmetric and asymmetric
-
All T10/T11 standards-compliant non-Sun symmetrical
disk devices
-
Many non-Sun asymmetrical disk arrays
Note –
T10 ALUA support has been added
for asymmetrical devices that support this T10 standard. Contact your storage vendor
to see whether your device is supported.
-
I/O load balancing –
In addition to providing simple failover support, the Sun StorageTek Traffic
Manager software can use any active paths to a storage device to send and receive
I/O. With I/O routed through multiple host connections, bandwidth can be increased
by the addition of host controllers. The software uses a round-robin load-balancing
algorithm by which individual I/O requests are routed to active host controllers
in a series one after the other.
-
Queue depth – SCSI
storage arrays present storage to a host in the form of a logical unit number
(LUN). LUNs have a finite set of resources available, such as the amount of
data that can be stored, as well as the number of active commands that a device
or LUN can process at one time. The number of active commands that can be
issued before a device blocks further I/O is known as queue depth. When the
Sun StorageTek Traffic Manager software is enabled, a single queue is created
for each LUN regardless of the number of distinct or separate paths it may
have to the host. This feature enables the disk driver to maintain and balance
one queue to the LUN, effectively managing queue depth. No other multipathing
software available for the Solaris 10 OS has this ability.
-
stmsboot command –
The Solaris 10 OS includes the stmsboot(1M) command, which
allows you to enable or disable the Solaris OS Multipathing software on your
boot device after the OS installation has been completed. This command is
available for both SPARC and x86/x64 systems, and provides support for SAS
multipathing with the Solaris 10 Update 5 OS.
SAS multipathing is not enabled by default in the Solaris
10 Update 5 OS for
either SPARC or x86/x64 hosts, so use of the stmsboot command
is required as a post-installation step if you wish to enable Multipathing.
SPARC hosts do not enable multipathing for Fibre Channel devices by
default, so use of the stmsboot command is required as
a post-installation step.
X86/x64 hosts do enable multipathing of Fibre Channel devices by default,
so the use of the stmsboot command is not mandatory as
a post-installation step.
-
Dynamic reconfiguration –
The Sun StorageTek Traffic Manager software supports the Solaris
10 OS dynamic
reconfiguration (DR).
Supported Standards
The
Sun StorageTek Traffic Manager software is based on open standards for communicating
with devices and device
management, ensuring interoperability with other standards-based devices and
software. The following standards are supported by the Sun StorageTek Traffic
Manager software:
-
ANSI Standard: Information Technology – SNIA Multipath
Management API Specification (ANSI INCITS 412-2006)
-
T10 standards, including SCSI-3, SAM, FCP, SPC, and SBC
-
T11.3 FC standards, including FC-PH, FC-AL, FC-LS, and FC-GS
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T11.5 storage management standards, including FC-HBA
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IETF standards, including RFC 2625
-
Serial Attached SCSI-2 (SAS2)
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