Note: The information contained in this article is structured as help information for the System Management Interface Tool (SMIT) and is not intended for use as a procedural or conceptual article.
Multipath I/O (MPIO) provides for multiple connections between a device and various controllers or adapters. These devices can be listed,, changed, removed, or configured just like other devices. However, they also have paths associated with them. These paths can also be listed, changed, removed, or configured. MPIO Management provides you with the most common tasks that you can perform for these devices and their paths. Other implementations for multiple paths between devices and adapters are also supported, but cannot be managed from MPIO Management.
Provides options for managing MPIO paths. Paths can be listed, exported to a file, enabled, disabled, configured, removed, or changed. You can also add new paths.
Provides options for managing MPIO devices. MPIO devices can be listed, changed, configured, or removed.
Displays a list of parent devices of MPIO devices.
Displays a list of all paths, paths for a specific device, or paths under a specific parent.
Provides options for enabling paths. Paths can be Defined or Available. Configuring a path makes it Available. Available paths can be enabled, disabled, or failed. Only paths that are enabled are used for I/O. Normally, a path is enabled when it is configured, however, there are times when a path must be explicitly enabled.
Provides options for configuring paths. A path must be configured to the Available state in order for it to be enabled for I/O. Only paths that are currently Defined or Missing can be configured. If a path status is enabled, disabled, or failed, it is already configured to the Available state and configuring it again does nothing.
Provides options for adding paths. Paths can be added automatically or manually. They are added automatically by running the cfgmgr command. This causes new paths and new devices to be detected and configured. It may also result in previously unconfigured paths and devices being configured again. A new path between a device and a parent device can also be added manually. The device name, parent name, and connection information is needed in order to do this. Knowing the connection information may require specific knowledge of the type of device involved as such information can be of different formats for different types of devices.
Displays information about the MPIO paths on the system. MPIO devices actually represent both a physical device and an algorithm for managing the I/O over the paths to the device. This algorithm is known as a Path Control Manager, or PCM. A path might have characteristics that are defined by the particular physical device and characteristics that are defined by the PCM. These path characteristics are similar to device characteristics. Some are informational only while others can be configured. SMIT support for specific devices and PCMs must be provided for these characteristics to be displayed and changed using SMIT. If there is no SMIT support installed, a message indicating that there are no additional SMIT screen entries available for this item is displayed.
Provides options for disabling paths. Paths can be Defined or Available. Configuring a path makes it Available. Available paths can be enabled, disabled, or failed. Only paths that are enabled are used for I/O. Normally, a path is enabled when it is configured. A path can be explicitly disabled to prevent it from being used for I/O.
Provides options for removing paths. A path can be unconfigured to put it in the Defined state or it can be deleted completely from the Device Configuration database. Either choice might be necessary if a path is to be physically removed from the system.
Provides options for listing and exporting all paths. All paths or just those with a specific path status can be displayed. The list of paths can be sorted by device name, status, or parent name. The list of paths can also be exported to a file.
Indicates that only paths of the selected status are to be displayed. Values can be All (default), Enabled, Disabled, Defined, Available, or Missing.
Indicates how the paths will be sorted when displayed. Choices are device name (default), path status, or parent name.
Writes the path information to a selected file. The path information is written in fields separated by colons (:), with one path per line.
Lists and displays all the paths only for the specified MPIO device.
Type a valid MPIO device name or select it from the list. Press the F4 key to present the list of choices.
Lists and displays all the paths only for the specified parent device.
Type the device name of a valid parent of an MPIO device or select it from the list. Press the F4 key to present the list of choices.
Allows you to enable specific disabled paths or to enable all disabled paths.
You can select "All Paths" to enable all disabled paths at one time or you can select or specify an individual disabled path to enable. The default is "All Paths".
Allows you to enable specific disabled paths or all disabled paths for a particular MPIO device.
The name of the selected MPIO device. You can type the name or select it from a list. Press the F4 key to present the list of choices.
Allows you to enable specific disabled paths or all disabled paths under a parent device.
The name of the selected parent device. You can type the name or select it from a list. Press the F4 key to present the list of choices.
Allows you to configure all Defined paths or selected Defined paths to the Available state.
You can select "All Paths" to configure all Defined paths at one time or you can select or specify an individual Defined path to configure. The default is "All Paths".
Allows you to configure specific Defined paths or all Defined paths for a particular device to the Available state.
Allows you to configure specific Defined paths or all Defined paths under a parent device to the Available state.
Allows you to run the cfgmgr command to automatically detect and configure all new devices and paths. To run the cfgmgr command, select "Yes". This is the default. To add a single specific path as defined by device name, parent name, and connection, select "No".
Type a valid connection for the path. A valid connection depends on the type of device and must contain the actual physical connection of the path to the parent device.
Allows the device and PCM characteristics of a path to be displayed or changed. Device and PCM specific SMIT support must be provided for these characteristics to be displayed and changed using SMIT. If there is no SMIT support installed, a message indicating that there are no additional SMIT screen entries available for this item is displayed.
Allows the device and PCM characteristics of a path, selected from the paths belonging to a device, to be displayed or changed. Device and PCM specific SMIT support must be provided for these characteristics to be displayed and changed using SMIT. If there is no SMIT support installed, a message indicating that there are no additional SMIT screen entries available for this item is displayed.
Allows the device and PCM characteristics of a path, selected from the paths under a parent, to be displayed or changed. Device and PCM specific SMIT support must be provided for these characteristics to be displayed and changed using SMIT. If there is no SMIT support installed, a message indicating that there are no additional SMIT screen entries available for this item is displayed.
Type or select a valid MPIO path. Press the F4 key to present the list of choices.
Allows you to disable specific enabled paths.
Allows you to disable specific enabled paths, selected from the paths for a device.
Allows you to disable specific enabled paths, selected from the paths under a parent.
Select the individual enabled paths that you want to disable. Press the F4 key to present the list of choices.
Allows you to unconfigure a specific path (place in the Defined state), or to delete it from the Device Configuration database, or to do both.
Allows you to unconfigure a specific path (place in the Defined state), selected from the paths for a device, or to delete it from the Device Configuration database, or to do both.
Allows you to unconfigure one or more paths (place in the Defined state), selected from paths under a parent, or delete it from the Device Configuration database, or to do both.
Select the path you want to remove. Press the F4 key to present the list of choices.
Allows you to unconfigure a path to the Defined state, or to unconfigure, then delete it from the Device Configuration database. Select "Yes" to unconfigure the path and leave it in the Defined state. Select "No" to unconfigure and delete the path.
You can select "All Paths" to remove all paths under a parent device at one time or you can select or specify an individual path to remove. The default is "All Paths".
Displays a list of all MPIO devices in the system.
Displays a list of all the MPIO devices under a selected parent.
Displays a list of all of the parent devices for a selected MPIO device.
Displays information about the MPIO devices on the system. MPIO devices actually represent both a physical device and an algorithm for managing the I/O over the paths to the device. This algorithm is known as a Path Control Manager, or PCM. A device might have characteristics that are defined by the particular physical device and characteristics that are defined by the PCM. Some are informational only while others can be configured. SMIT support for specific devices and PCMs must be provided for these characteristics to be displayed and changed using SMIT. If there is no SMIT support installed, a message indicating that there are no additional SMIT screen entries available for this item is displayed.
Makes a defined device available for use by the operating system.
Allows you to remove an MPIO device. When you delete a device, you can make the device unavailable, but still defined, or remove the device definition from the Customized database.
Allows you to list, enable, disable, configure, remove, or change a device's path. You can also add new paths.
Lists all parents of MPIO devices in the system.
A parent device's paths can be listed, enabled, disabled, configured, removed, or changed. New paths may also be added.
Allows you to change the characteristics of the Path Control Module path. These include the path priority and initial state.
Logical device name of the device associated with this path. Information in this field cannot be changed.
Logical parent name of the adapter associated with this path. Information in this field cannot be changed.
SCSI ID and LUN ID of the device associated with this path. This is the connection information. The connection information differentiates the multiple path instances that share the same logical parent (adapter). Information in this field cannot be changed.
The priority of this path relative to other paths associated with the device. A lower number is a higher priority. Valid values are 1 through 255. The failover algorithm determines the order that the paths are selected upon the active path failing. The round robin algorithm determines the distribution of I/O across the enabled paths. Press the F4 or Tab keys to present a list of values you can select.
The initial state of the path after a reboot. This allows a path to be disabled across machine reboots. You can use this to prevent paths from being used by the Path Control Module for sending I/O. Valid values are Enabled and Disabled. Press the F4 or Tab keys to present a list of values you can select.
Allows you to change the Path Control Module device characteristics. These are characteristics specific to the device but that alter the manner in which the Path Control Module manages the paths.
The type of device being supported by Path Control Module. Information in this field cannot be changed.
The name of the Path Control Module being used to support this device. Information in this field cannot be changed.
Displays the current path algorithms and allows you to select alternate path control algorithms supported within this Path Control Module. Press the F4 or Tab keys to present a list of values you can select.
Displays the current reservation policy and allows you to select alternate reservation policies supported within this Path Control Module. Press the F4 or Tab keys to present a list of values you can select.
Determines which types of device paths are health checked. The PCM checks the continuity of a path and the ability of the target device to process commands. If this check is successful, the path will be enabled. If the check fails, the path is left in its current state.
Select "enabled" to check only paths that are in the enabled state and have no active I/O.
Select "failed" to check only paths that are in the failed state.
Select "nonactive" to check only paths with no active I/O.
Specify how often the health check should run on paths that meet the health check mode criteria. You can select a value from 0 through 3600 units of seconds. Selecting a value of "0" disables the health check.
The target device supports LUN reset. Setting this attribute to YES will cause the device driver to issue a LUN reset instead of a target reset.
This attribute sets the maximum time that the device driver will hold off I/O in response to certain error conditions. This attribute helps to minimize the number of I/Os which need error processing and reduces failover times.
Adjusts the duration of a sample time of the distributed error detection algorithm. The unit of measure is in milliseconds. You can specify a value from 10ms through 1000ms. The default value is 50ms. A lower value decreases the time duration of each sample taken and decreases the algorithm's sensitivity to small bursts of I/O errors. A higher value increases the algorithm's sensitivity to small bursts of errors and the probability of failing a path.
Adjusts the point where the distributed error detection algorithm will fail a path because of poor performance. You can specify a range from 0 through 100. The distributed error detection algorithm will be disabled when the attribute is set to zero (0). The default setting is zero. The distributed error detection algorithm samples the fabric connecting the device to the adapter for errors. The algorithm calculates a percentage of samples with errors and will fail a path if the calculated value is larger than the Distributed Error Percentage.
The worldwide name and LUN ID of the device associated with this path. The connection information recognizes the different multiple path instances that share the same logical parent (adapter). Information in this field cannot be changed.
Determines the type of SCSI command that will be used during health check operations. The supported values are test_unt_rdy (default) and inquiry.
Specifies the Unique Device Identifier of a disk. This is a combination of product ID, manufacturer ID and serial number.
Allows you to query the reservation status and the persistent reservation values. Also, it allows you to release a single path or persistent reservation.
Displays the status of the device (opened or closed), the ODM reservation policy (Single Path or Persistent Reservation), and the device reservation policy.
Displays information about the persistent reservations, reservation keys, and the persistent reservation capabilities of the device.
Releases a single path or a persistent reservation on a device.