The following sections describe the features and benefits of Oracle Solaris I/O multipathing.
The Oracle Solaris I/O multipathing is enabled by default on both SPARC-based and x86-based systems and has the following features:
Supports dynamic reconfiguration (DR) operations.
Path management – Manages the path to any storage device dynamically that the Oracle Solaris OS supports. The addition and removal of paths to a device is done automatically when there is a change in path configuration.
Failover support – Manages the failure of storage paths while maintaining host I/O connectivity through the available secondary path. This feature implements higher levels of reliability, availability, and serviceability (RAS), which requires redundant host connectivity to storage devices.
Symmetric and asymmetric device support – Supports symmetric and asymmetric disk storage devices.
I/O load balancing – Provides I/O load balancing by routing I/O through multiple host connections along with simple failover support.
Queue depth – Used for flow control. SCSI storage arrays present storage to a system in the form of a logical unit. A logical unit has a finite set of available resources, such as the amount of data that can be stored and the number of active commands that a device can process at a time. The number of active commands that can be issued before a device blocks further I/O is known as queue depth. With Oracle Solaris I/O multipathing, a single queue is created for each logical unit regardless of the number of distinct or separate paths it might have to the host.
Persistent device naming – Maintains device naming of the configured devices even after the reboot or reconfiguration of the system. The only exception to this policy are tape devices found in the /dev/rmt file, that do not change unless they are removed and then regenerated.
Devices with multiple paths are displayed as a single device instead of one device per path. This feature reduces the cost of managing complex storage architectures with utilities, because the Oracle Solaris I/O multipathing feature is completely integrated with the Oracle Solaris OS. For example, the format command or a volume management product sees a device with multiple paths as one representation of a storage device instead of multiple devices for each path.
The failover support in Oracle Solaris I/O multipathing enables you to implement higher levels of RAS, which requires redundant host connectivity while maintaining host I/O connectivity to storage devices.
Oracle Solaris I/O multipathing can use any active path to a storage device to send and receive I/O. With I/O routed through multiple host connections, you can increase the bandwidth by adding host controllers.
Oracle Solaris I/O multipathing allows you to combine iSCSI and FC paths to a single target.