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Powerpath


powercf

During installation on Solaris hosts, the powercf utility configures PowerPath devices by scanning the host adapter buses for both single-ported and multiported Symmetrix volumes. (A multiported volume shows up on two or more host bus adapters with the same Symmetrix subsystem/device identity. The identity comes from the serial number for the volume.) For each Symmetrix volume found in the scan of the host adapter buses, powercf creates a corresponding emcpower device entry in the emcp.conf file, and saves a primary path and an alternate primary path to that device. The powermt config command, run at boot time by init (1M), adds additional paths to the Symmetrix volume.

After PowerPath is installed, you only need to run the powercf command when the physical configuration of the Symmetrix or the host changes. The configuration changes that require you to reconfigure PowerPath devices include:
• Adding or removing host bus adapters
• Adding, removing, or changing Symmetrix logical devices
• Changing the cabling routes between host bus adapters and Symmetrix ports
• Adding or removing Symmetrix channel directors

powercf -i|p|q

Arguments

-i
Scans the host adapter buses for single-ported and multiported Symmetrix volumes. Compares those volumes with the PowerPath device entries in the emcp.conf file. Prompts you to accept or reject any addition or deletion of Symmetrix devices in the emcp.conf file.

-p
Scans the host adapter buses for single-ported and multiported Symmetrix volumes. Compares those devices with the emcpower entries in the emcp.conf file. Prints information on any inconsistencies.

-q
Scans the host adapter buses for single-ported and multiported Symmetrix volumes. Compares those volumes with the PowerPath device entries in the emcp.conf file. Updates the emcp.conf file by removing PowerPath devices that were not found in the host adapter scan and by adding new PowerPath devices that were found. Saves a primary and an alternate primary path to each PowerPath device.

The powermt Commands

This section describes each powermt command. Refer to the preface of this document for information on the conventions used in the command syntax. You can run powermt commands from either the command line.

Powermt

Displays the syntax for the commands in the powermt management utility.

Syntax
powermt
powermt check

Verifies that all paths are connected to the correct Symmetrix volumes.

Syntax
powermt check [dev=power#|all] [adapter=adapter#|all]

The dev parameter and the adapter parameter are optional. You must, however, specify at least one in the powermt check command.

powermt check_registration

Provides PowerPath license registration information. The powermt check_registration command is available from the command line only. It does not have an equivalent SMIT command.

Syntax
powermt check_registration

powermt config
Configures paths to all known Symmetrix logical devices for maximum accessibility.

Syntax
powermt config

powermt display
Displays a table that shows the state of all host adapters found by PowerPath.

Syntax
powermt display

powermt display dev
Displays a table that shows the state of the specified PowerPath device or all PowerPath devices.

Syntax
powermt display dev=power#|all

powermt restore
Attempts to reopen, or restore to service, all device paths currently marked as Closed.

Syntax
powermt restore

powermt save
Saves changes to the PowerPath devices’ policy and priority attributes to the ODM so that the new values are in effect at system startup.

Syntax
powermt save

powermt set adapter_switch
Enables or disables the specified host adapter.

Syntax
powermt set adapter_switch=disabled|enabled adapter=adapter#

Parameters

disabled
Does not allow the specified host adapter to accept I/O traffic for any device path it serves.

enabled
Allows the specified host adapter to accept I/O traffic for any device path it serves.

adapter#
The host adapter number shown in the ## column in the table displayed when you enter the powermt display dev command.

powermt set mode
Sets device path(s) to either active or standby mode for the specified PowerPath device or for all PowerPath devices on the specified adapter.

Syntax
powermt set mode=active|standby adapter=adapter# [dev=power#|all]

The dev parameter is optional. If you do not include the dev parameter, the powermt set mode command changes the mode of all PowerPath devices on the specified adapter.

powermt set policy
Sets the load balancing policy for the specified PowerPath device or all PowerPath devices.

Syntax
powermt set policy=rr|io|lb|so [dev=power#|all]

The dev parameter is optional. If you do not include the dev parameter, the powermt set policy command changes the policy of all PowerPath devices.

Parameters


Rr Round-robin. Future I/O requests are assigned to each of the available paths in rotation.

Io I/O. Load balance is based on the number of pending I/Os.

Lb Least blocks. Load balance is based on the number of blocks in the pending I/Os.

powermt set priority
Sets the I/O priority for the specified PowerPath device or for all PowerPath devices.

Syntax
powermt set priority= [dev=power#|all]

The dev parameter is optional. If you do not include the dev parameter, the powermt set priority command changes the priority of all PowerPath devices.

The powermt set priority command is only meaningful when the load-balancing policy is Symmetrix optimized (so). This setting allows the I/O performance of a few, individual PowerPath devices to be improved at the expense of the rest of the devices, while otherwise maintaining the best possible load balance across all paths.

powermt validate
Verifies that the primary path opened for each PowerPath device is connected to the correct Symmetrix volume.

Syntax
powermt validate

powermt watch
Displays a table that shows the state of the host adapters for the specified PowerPath device or all PowerPath devices.

Syntax
powermt watch every=#seconds

powermt watch dev
Displays a table that shows the state of the specified PowerPath device or all PowerPath devices.

Syntax
powermt watch dev=power#|all every=#seconds

  • Sundar Emc

    Can Powerpath be used to discover LUNs and manage them from a third party array?
    I am specifically looking at Compellent.

    powermt manage class= (what code should i use for Compellent?)

  • Arsalan

    i’ve run powermt unmanage……….and now that device is not showing up…
    when i tried to run the command powermt manage it returns an error..
    is there any command to get the unmanaged device back……?????

    another thing..that unmanaged device is showing up in the command powermt display umanaged…..

  • Joseph

    In the later version of Power Path we have the option to discover devices if its in Linux.