Dell EMC Exam D-PSC-MN-01 Topic 3 Question 5 Discussion

In a Dell EMC PowerScale cluster, each node is assigned a Logical Node Number (LNN) that identifies it within the cluster. When nodes are added or removed (e.g., via SmartFail), LNNs may become non-sequential. To modify the LNNs and restore sequential order, specific commands must be used.

Steps to Modify the LNN for a Node:

Enter Configuration Mode:

Use the isi config command to enter the configuration shell.

# isi config

This mode allows for administrative tasks that can alter the cluster configuration.

Use the lnset Command:

The lnset command is used to set the LNN of a node.

# lnset --sn <SNO> <new-LNN>

--sn <SNO> specifies the serial number of the node.

<new-LNN> is the desired Logical Node Number.

Example:

If you want to set the LNN of a node with serial number ABC12345 to 6:

# isi config

# lnset --sn ABC12345 6

Why Option C is Correct:

Accurate Command Sequence:

Option C correctly specifies entering isi config, followed by using lnset with the serial number (<SNO>) and the new LNN.

Proper Syntax:

The command includes all necessary parameters to change the LNN.

Why Other Options Are Incorrect:

Option A and B:

Commands isi device node and isi node with --lnn options are incorrect or incomplete for changing LNNs.

Option D:

Simply stating lnset without specifying the serial number and new LNN is insufficient.

Dell PowerScale Reference:

Dell EMC PowerScale OneFS CLI Administration Guide:

Section on Node Management Commands:

Details the usage of isi config and lnset commands.

Provides syntax and examples for changing LNNs.

Notes on LNN Changes:

Warns that changing LNNs can impact cluster operations and should be performed during maintenance windows.

Best Practices:

Before Changing LNNs:

Ensure that the cluster is in a healthy state.

Notify users of potential service impacts.

Backup critical configuration data.

During LNN Change:

Carefully input the serial number and desired LNN to avoid mistakes.

Verify that the new LNN is not already in use.

After Changing LNNs:

Exit the configuration mode with exit.

Check cluster status using isi status to confirm that the node has been assigned the new LNN.

Update any documentation to reflect the new node numbering.

Caution:

Modifying LNNs is an advanced operation that can affect cluster communication.

It is recommended to consult Dell EMC Support or refer to official documentation before proceeding.