Use the commands in this section for managing multipath I/O failover for NSS devices on NetWare. 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.
IMPORTANT:The Media Manager multipath I/O management is not available for Linux. For devices on Linux, use the Linux multipath I/O management tools. For information, Section 15.0, Managing Multipath I/O to Devices (Linux).
This command lists all of the failover devices. It also lists all the paths associated with each device, their assigned priorities, and the path that is selected.
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.
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:
0x12 [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 0x12. Number 11 is up, and it has been assigned the highest priority of 1. The status of “Up” means that this path is available for use. The status of “selected” means the path is the primary path, and that any disk requests that are trying to reach the 0x12 device automatically go through that 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.
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.
If the /insert option is not used, the specified path replaces the current path that is set at that priority level.
If the /insert option is used, the command inserts the specified path at the specified priority instead of replacing the current path set for that 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.
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, to become the primary path.
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. The pathid must be a valid path ID.
If the Down option is followed by the /setpath option, NSS automatically selects the highest priority path from among all paths that are currently in the Up state to become the primary path.
Whenever a path is bad, NSS automatically moves the path to a Down state.
This command activates the specified path as “selected”, which means that 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.
This command forces the device to reselect the highest priority path that is online. The deviceid must be a valid device ID.
This command resets the multipath settings in the operating system registry (such as entries in HKEY_LOCAL_MACHINE\Software\Novell\MediaManager\Failover\), and re-creates them based on the current set of failover devices.