C H A P T E R 1

Product Overview

This chapter provides an overview of the Solaris Fibre Channel (FC) and Storage Multipathing software. This information will prove helpful during installation and configuration of the software.

The Solaris FC and Storage Multipathing software is integrated in the Solaris 10 OS. Whether the system that is being upgraded has prior version of the Solaris FC and Storage Multipathing software installed or not, there is no need to separately install the software package during or after the Solaris 10 OS installation. That applies to the Solaris 10 OS new (initial) install as well.

In Solaris 10 OS, fabric-connected devices are configured and made available to the host automatically during install and boot time.

Note - If performing an upgrade and if you want to make any FC devices unavailable after upgrade, those devices have to be manually unconfigured using "cfgadm -c unconfigure" commands. However, to make those devices permanently unavailable to the system, you may want to consider using switch zoning and/or LUN masking. The changes made by cfgadm unconfigure will not persist after a reboot unless manual configuration for fabric-connected devices has been turned on. To disable the fabric devices discovery during boot or install, please refer to Appendix A titled, Manual Configuration for Fabric Connected Devices.

This chapter contains the following sections:

Software Features

Supported Standards

Software Features

In general, the Solaris Fibre Channel and Storage Multipathing software enables FC connectivity for the Solaris hosts. The software resides on the server and identifies the storage and switch devices on your SAN. It allows you to attach either loop or fabric SAN storage devices while providing a standard interface with which to manage them.

Fibre Channel Software Features

The Solaris FC and Storage Multipathing software provides the following key features:

Dynamic Storage Discovery - The Solaris FC and 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 - Devices that are configured within the Solaris FC and Storage Multipathing software maintain their device naming through reboots and/or reconfiguration. The only exception to this are tape devices, found in /dev/rmt, will not change unless they are removed and later regenerated.

FCAL Support - OpenBoot Prom (OBP) commands that are used on servers can access Fibre Channel-Arbitrated Loop (FCAL) attached storage for scanning the FC loop.

Fabric Booting - Sun 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 (SNIA) Fibre Channel HBA(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 StorEdge 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 Operating System. For additional information on FC specifications refer to http://www.t11.org.

Multipathing Software Features With Fibre Channel Storage

The Solaris 10 OS contains the Solaris FC and Storage Multipathing software. This is enabled by default for x86-based platforms and optional for SPARC-based platforms. The software contains the following features:

Path Management - The Solaris FC and Storage Multipathing 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 allows hosts configured with the Solaris FC and Storage Multipathing 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. For Sun storage, there are no 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 multipathing software.

Single Device Instances - Unlike other multipathing solutions, the Solaris FC and Storage Multipathing software is fully integrated with the Solaris 10 OS. This allows the Solaris FC and Storage Multipathing software to display multipath devices as single device instances instead of as one device, or device link, per path. This reduces the cost of managing complex storage architectures, since it enables utilities, such as format(1M) or higher level applications such as the Solaris 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 Solaris FC and Storage Multipathing software manages the failure of storage paths while maintaining host I/O connectivity through available secondary paths.

Symmetrical/Asymmetrical Device Support - The Solaris FC and Storage Multipathing software support the following disk storage devices.

All Sun disk storage - both symmetric and asymmetric

All T10/T11 standards complaint non-Sun symmetrical disk devices

Many non-Sun Asymmetrical disk arrays.

Please contact your storage vendor to see if your device is supported.

In addition, T10 ALUA support has been added for those asymmetrical devices that support this T10 standard.

I/O Load Balancing - In addition to providing simple fail over support, the Solaris FC and Storage Multipathing 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 Solaris FC and Storage Multipathing 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 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 know as queue depth. When the Solaris FC and Storage Multipathing 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 allows the disk driver to maintain and balance 1 queue to the LUN, effectively managing queue depth. No other multipathing softwares available for the Solaris 10 OS can claim this.

stmsboot Command - The Solaris 10 OS cannot be installed initially onto the Solaris multipathing software devices. However, the stmsboot command, which is included with the Solaris FC and Storage Multipathing software, allows you to enable the Solaris Multipathing software on the boot device after the installation has been completed for SPARC devices.

Dynamic Reconfiguration - The Solaris FC and Storage Multipathing Software supports the Solaris 10 OS Dynamic Reconfiguration (DR).

Supported Standards

The Solaris FC and Storage Multipathing 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 Solaris FC and Storage Multipathing software:

T10 standards, including SCSI-3, SAM, FCP, SPC, and SBC

T11.3 FC standards, including FC-PH, FC-AL, FC-LS, and FC-GS

T11.5 storage management standards, including FC-HBA

IETF standards, including RFC 2625