10.7 Managing Multiple Paths with Server Console Commands

When you use the server console to assign multiple paths, you can also assign a priority level to each path, according to which paths you want used first and last. The lower the number, the higher the priority. This number determines which path to take; if the current path fails, the path with the next highest priority is used. Multiple paths can have the same priority level. These values are persistent and they are stored in the registry.

The following commands are available from the server console:

Media Manager Multipath I/0 Console Command

Description

 
list failover devices device_id

This command lists all of the failover devices, all the paths associated with each device, their assigned priorities, and the selected primary path.

To list the paths associated with all the devices on the server, enter the command without specifying the device_id.

To list the paths associated with a given device, enter the command followed by the device_id.

For example, to see the paths associated with a device with device_id 0x12, enter the following at the server console

list failover devices 0x12

The list provides output similar to the following results:

Ox12 [V132-A1-D2:20] ABC DEVICE rev:5678

Up 11 [V132-A1-D2:20] ABC DEVICE rev:5678 Priority = 1 selected

Up 26 [V132-A1-D2:20] ABC DEVICE rev:5678 Priority = 2

In this example, two paths are assigned to device Ox12. Number 11 is Up, and it has been assigned the highest priority of 1. The word Up simply means that this path is available for use. The word selected means that any disk requests that are trying to reach the Ox12 device automatically go through the 11 path, because it is set as the primary path. In this example, you could use the mm set failover path command to override the priorities and make the number 26 path to be the primary path used. 

mm set failover priority pathid=number

This command sets the priority level for the selected path. The pathid must be a valid path ID. The number is the priority to set for the selected path. The number must be a decimal integer value between 1 and 4 million, with 1 being the highest priority and 4 million being the lowest priority. 

mm set failover priority pathid=number /insert

The /insert option inserts the specified path with its specified priority. For example, if you have four existing paths that are assigned the priorities of 1, 2, 3, and 4, and you enter a new path followed by a number 2 and the /insert option, then the paths that were previously assigned to 2, 3, and 4 priority are bumped to priority 3, 4, and 5 in order to accommodate the new path that has been assigned priority 2.

 
mm set failover state pathid=up /setpath

This command sets the state of the specified path to Up. The pathid must be a valid path ID.

If the Up option is followed by the /setpath option, NSS automatically selects the highest priority path from among all the paths that are in the Up state, including the new path. 

mm set failover state pathid=down /setpath

This command enables you to designate a path to be in the Down state so you can perform preventative maintenance or reroute cables on a good, functional path. If the path is bad, NSS automatically moves the path to a Down state.

If the Down option is followed by the /setpath option, NSS automatically selects the highest priority path from among the other paths that are currently in the Up state.

 
mm set failover path pathid

This command activates the selected path as selected, which means it serves as the primary path. The pathid must be a valid path that is currently in the Up state. The priority of a path remains static regardless of whether a path is considered up or down or whether a path is selected or not selected as the primary path. 

mm restore failover path device_id

This command forces the device to reselect the highest priority path that is online. The deviceid must be a valid device ID. 

mm reset failover registry

This command resets the multipath settings in the operating system registry.