Failure phenomenon:
Article reproduced from EMC Chinese Support forum
PowerPath integrates multipath I/O, automatic load balancing, and path failover capabilities to make storage management easier. This article summarizes the use of PowerPath common commands for operational considerations, for host system administrators to the hba/path/port/disk device/Storage system to perform configuration, view, delete, save, restore and other operations to provide a reference.
Solution:
Power Check
Features: Check PowerPath configuration
Platform: all PowerPath Platforms
Storage System: All storage Systems
Format: POWERMT Check
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all] [Force] [Reconfig]
Note: Check the path and remove the path marked as dead from the PowerPath configuration, if necessary.
If the path is marked Dead or the serial number in the path configuration information does not match the local device serial number, the following prompts the user to delete the path:
Warning:storage_system I/O path path_name is dead.
Do your want to remove it (y/n/a/q)?
Y: Delete dead path and continue checking for remaining paths;
N: Do not delete dead path, but continue to check the remaining path;
A: Delete dead path and all subsequent paths marked as dead;
Q: Do not delete dead path and exit the command. Deleted path remains deleted.
Parameters:
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Restrict command Check for specified storage type, default to all;
Force: Suppresses confirmation prompts and deletes all paths marked as dead;
Hba=hba#|all: Restricts checking for specified HBAs. defaults to all;
Dev=path|device|all: Restricts checking for the specified path, or specifies all path for device. The default is all.
Reconfig: Reconfigure the mismatched path. This command is only valid for Windows and Solaris.
POWERMT check_registration
function: Check license information
Platform: all PowerPath Platforms
Storage System: All storage Systems
Format: powermt check_registration
Note: Check the PowerPath license information on the host: valid, expired, invalid, or not license.
POWERMT Config
Features: Configuring Paths for logical devices
Platform: UNIX and Linux platforms
Storage System: All storage Systems
Format: POWERMT config
Note: Configure all the detected Symmetrix and CLARiiON Logical disk devices as PowerPath disk devices and add them to the PowerPath configuration as well as to the supported Third-party storage System logical devices.
The command configures all detected paths to the PowerPath disk device and adds these paths to the PowerPath configuration.
This command does not delete a previously configured path when it becomes dead path.
POWERMT Disable HBA
Function: Disable HBA port
Platforms: AIX and Solaris Fibre Channel, HP-UX iSCSI and Fibre Channel, Linux iSCSI and Fibre Channel
Storage System: All storage Systems
Format: powermt Disable Hba=hba
Note: Disables all paths to the specified HBA configuration. Stop all I/O on the port, and turn off all disk devices configured for the port.
The user is required to perform this command when replacing the I/O on which the HBA stops. When the HBA port is disabled, all paths configured through the HBA port are dead labeled in the output of the command powermt display Dev=device.
Note the following restriction conditions:
· A disabled HBA will no longer exist after the host restarts;
· This command returns failure if PowerPath load balancing and failover policies are BF or Nr.
View the HBA status as disabled or active, using the command powermt display Hba_mode.
Parameters:
Hba=hba: Disable the specified HBA port with the HBA ID on the host, for example: 1280.
POWERMT Display
Features: monitor HBAs and disk devices
Platform: all PowerPath Platforms
Storage System: All storage Systems
Format:
POWERMT display [Paths|ports]
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
POWERMT display [ports] [Dev=device|all]
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
Parameters:
Paths: Each line displays a path information
Ports: Display one port information per line
Dev=device|all: Displays the specified disk device information, all showing all disk devices.
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Lists the specified storage System information, all showing all storage systems. The default is all.
Function: Monitor HBA mode
Platform: UNIX and Linux platforms
Storage System: All storage Systems
Format: powermt display Hba_mode
Remarks: Displays all HBA information configured on the host. Lists the activation or disabled status of the HBA.
POWERMT Display Port_mode
Function: Display storage-System port mode
Platform: UNIX and Linux platforms
Storage System: All storage Systems
Format: powermt display Port_mode Dev=device
Remarks: Displays all port mode information configured on the host. Lists the activation or disabled status of the HBA.
Dev=device: Specifies the disk device port that you want to view. The disk device name needs to be a native device name.
Function: Activate HBA port
Platforms: AIX and Solaris Fibre Channel, HP-UX iSCSI and Fibre Channel, Linux iSCSI and Fibre Channel
Storage System: All storage Systems
Format: POWERMT Enable Hba=hba
Note: Activates the previously disabled HBA port. Run this command to restore I/O to the specified HBA port and its disk devices. If PowerPath load balancing and failover mode is BF or NR, the command returns a failure.
HBA=HBA activates the specified HBA port.
Function: Load User Configuration
Platform: all PowerPath Platforms
Storage System: All storage Systems
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
Note: Read the following from the saved profile and apply to the current configuration: PowerPath disk device policy and priority; Write threshold settings and write queue depth; Periodic automatic restore settings and path mode.
If the configuration is saved by the POWERMT Save command in the default filename, the configuration will be loaded automatically when the system starts, (except for AIX, always load the default configuration at startup), and if the default filename is not used, the configuration will not load automatically at startup, and the user needs to use the POWERMT The load command loads the configuration manually.
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Restricts the command to the specified storage system by default of all.
File=pathname: Saves the full path name of the configuration file.
Function: Put a disk device or storage system into PowerPath management
Platform: UNIX and Linux platforms
Storage System: All storage Systems
Format: powermt manage{dev=device|
Class={symm|clariion|hitachi|hpxp|hphsx|invista|ess}}
Note: By default, all storage systems are under PowerPath management. Users can use POWERMT unmanage to make the storage system not managed by PowerPath. When the storage system defaults to PowerPath management, all of its logical disk devices are managed by PowerPath. You can use this command after using the POWERMT unmanage command to restore PowerPath's management of disk devices.
Dev=device: Specifies the path name of the logical disk device to be managed by PowerPath.
Class=symm|clariion|hitachi|hpxp|hphsx|invista|ess: Specifies the name of the storage system to be managed by PowerPath.
Function: Frees the pseudo-disk device name for reuse
Storage System: All storage Systems
Note: After adding and removing LUN configuration multiple times, Linux hosts and PowerPath can discover all devices, but PowerPath runs this command when it has finished using the pseudo device name of the disk device.
Function: Remove path from PowerPath management
Platform: all PowerPath Platforms
Storage System: All storage Systems
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
[Force] hba=hba#|all | Dev=path|device|all
Note: Removes the specified path from the PowerPath configuration path list. This command does not remove the disk devices involved in the path. As long as the logical device is visible in the system, the logical device can be configured with the POWERMT Config command.
On all platforms, if the native path is turned on, this command cannot remove it, for example, a file system is loaded on a path disk device, or an application has opened the path disk device. This command deletes all paths that are specified and are not open.
If the PowerPath disk device is open, this command does not remove the disk device and the last path to the device.
To permanently delete a path from the PowerPath configuration:
1. Run powermt check or powermt remove;
2. Physically remove the path;
3. Delete the operating system objects associated with the path and/or disk device;
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Restricts the command to the specified storage system by default of all.
Force: Do not eject the confirmation dialog and delete all specified paths, including the last path of the logical device.
Hba=hba#|all: Removes the path of the specified HBA and defaults to all.
Dev=path|device|all: Removes the specified path, or connects the path to the specified disk device by default of all.
Platform: all PowerPath Platforms
Storage System: All storage Systems
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
[Hba=hba#|all] [Dev=path|device|all]
Note: This command tests and restores the specified path, issues test I/O, and responds to the test results as follows:
· If the live path passes the test, the command does nothing;
· If the dead path passes the test, this command identifies it as a alive state; PowerPath can use the path at this time, and other paths on the same HBA and/or storage-system ports will also be tested.
· If the live path test fails, this command identifies it as dead and prints an alert. In addition, other paths to shared HBAs and ports may also be labeled as dead and tested.
· This command prints an alert if the dead path test fails.
In addition, the command tries to revive the dead volume:
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Restricts the command to the specified storage system by default of all.
Hba=hba#|all: Restores the path to the specified HBA, which defaults to all.
Dev=path|device|all: Restores the specified path, or connects the path to the specified disk device, by default, all.
Features: Saving User Configuration
Platform: all PowerPath Platforms
Storage System: All storage Systems
Format: POWERMT save [File=pathname]
Note: By default, this command saves the PowerPath configuration in the Powermt.custom file. The user can specify a different file name. For logical devices, commands record its serial number, policy, priority, write thresholds and queues, and pseudo device names. On the path, the command records its schema. For the storage system, this command records its periodic automatic restore settings.
The configuration is saved and can be loaded with the POWERMT load command.
File=pathname: Saves the configured file path name.
If the configuration is saved in the default filename, the previous profile will be overwritten.
Whenever users make changes to the host hardware, run this command to update the PowerPath configuration.
Features: Setting path mode
Platform: all PowerPath Platforms
Storage System: All storage Systems
Format: POWERMT set Mode=active|standby
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
[Hba=hba#|all] [Dev=path|device|all]
Remarks: Sets the path to active or standby state.
Mode=active|standby: Determines whether the path can transfer I/O or keep it.
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Restricts the command to the specified storage system by default of all.
Hba=hba#|all: Sets the path of the specified HBA, which defaults to all.
Dev=path|device|all: Sets the specified path, or the mode that connects the path to the specified disk device, defaults to all.
Features: Setting load balancing and failover policies
Platform: all PowerPath Platforms
Storage System: All storage Systems
Format: POWERMT set Policy=li|lb|rr|re
[Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all]
POWERMT set policy=si [Dev=device|all]
POWERMT set POLICY=SO|NR [Dev=device|all]
POWERMT set Policy=bf|co [Dev=device|all]
Policy=ad|bf|co|lb|li|nr|re|rr|si|so:ad (Adaptive), BF (Basic Failover), Co (CLARIION optimization), lb (least blocks), Li (least I/O), nr (no redirect), Re (request), RR (round robin), Si (Streamio), so (Symmetrix optimization)
Class=symm|clariion|ess|hitachi|hpxp|hphsx|invista|all: Restricts the command to the specified storage system by default of all.
Dev=device|all: Restricts the command to the specified disk device, and defaults to all.
