NS0-093 Exam Questions & Answers

To replace a drawer in a DS460c shelf, the following steps must be taken:

1. Disconnect the cable chains from the chassis

Why this is required: Cable chains connect the drawer to the shelf and must be disconnected to safely remove the drawer.

2. Evacuate all drives in the drawer

Why this is required: Drives must be removed to avoid damage during the drawer replacement process and to reduce the weight of the drawer for safe handling.

Why Other Options Are Incorrect:

A . Shut down both nodes:

This is unnecessary because DS460c shelves support online replacement, and the system can remain operational.

C . Power off the shelf:

This is also unnecessary. DS460c shelves are hot-swappable, meaning they do not require the shelf to be powered down.

'DS460c Hardware Service Guide' explains the procedure for replacing a drawer.

NetApp's 'Field Replacement Guide' for DS460c shelves emphasizes online and hot-swappable replacements.

When a WAFL inconsistency is detected, the first step is to stabilize the system before attempting any repairs or recovery.

Steps to Handle WAFL Inconsistency:

Stabilize the System:

Ensure that the system is not experiencing ongoing hardware or software issues.

Avoid making changes to the affected aggregate or volume until the system is stable.

Assess the Impact:

Determine which aggregates or volumes are affected and the severity of the inconsistency.

Why Other Options Are Incorrect:

A . Run wafliron:

Running wafliron should only be done after stabilizing the system and under guidance from NetApp Support.

C . Force offline the affected aggregate:

Forcing an aggregate offline without proper assessment can lead to data loss.

D . Run a dump to null:

Dumping data is not relevant for resolving a WAFL inconsistency.

'NetApp WAFL Troubleshooting Guide' specifies that stabilization is the first step after detecting inconsistencies.

NetApp Support documentation provides guidelines for handling WAFL inconsistencies safely.

To manually generate a kernel core file in ONTAP, the following commands can be used:

1. ::> reboot --node <node_name> --dump true

What it does: Reboots the specified node and generates a core dump before rebooting.

Example Usage:

reboot --node <node_name> --dump true

2. ::> halt --dump true --node <node_name>

What it does: Halts the specified node and generates a core dump before shutting down.

Example Usage:

halt --dump true --node <node_name>

3. ::> system node panic --node <node_name>

What it does: Forces a panic on the specified node, which triggers a kernel core dump.

Example Usage:

system node panic --node <node_name>

Why Other Options Are Incorrect:

A . SP> system power cycle:

This command reboots the system from the Service Processor but does not generate a core dump.

NetApp 'Kernel Core Dump Guide' explains the use of reboot, halt, and panic commands to trigger core dumps.

ONTAP CLI Reference includes the syntax for these commands.

To recover an inconsistent aggregate, the following tools can be used:

1. wafl_check

What it does: This tool is used to perform a consistency check on WAFL metadata. It identifies and attempts to fix WAFL inconsistencies in aggregates.

When to use: Run wafl_check after identifying WAFL inconsistencies to repair minor metadata issues.

2. wafliron

What it does: This tool repairs WAFL inconsistencies by reconstructing metadata. It is more powerful than wafl_check and should only be run under NetApp Support guidance, as improper use can result in data loss.

When to use: Use wafliron for severe WAFL inconsistencies that cannot be resolved by wafl_check.

Why Other Options Are Incorrect:

A . file check:

This is not a valid NetApp tool.

C . wafl snapiron:

While similar in name, snapiron is used for snapshot recovery, not aggregate recovery.

'ONTAP Aggregate Troubleshooting Guide' details the usage of wafl_check and wafliron.

NetApp Support documentation provides guidelines for recovering inconsistent aggregates.

Steps to Unfail a Disk in Maintenance Mode:

When a disk is marked as 'failed,' it is added to the Failed Disk Registry and marked as unusable by the system. Unfailing a disk involves removing it from this registry and resetting its state.

Step 1: Remove the Disk from the Failed Disk Registry

Use the command: registry remove <disk> to delete the disk from the Failed Disk Registry. This clears its 'failed' status.

Step 2: Use the Disk Unfail Command

Execute the disk unfail <disk> command to reset the disk status and make it available for use.

Key Notes:

After unfailing, the disk will be treated as a spare and must be reassigned or re-added to an aggregate.

If the disk remains failed after these steps, physical hardware issues may need to be addressed.

NetApp Reference Documentation:

The 'ONTAP Maintenance Mode Guide' and 'Disk Management Guide' provide detailed instructions for handling failed disks and using the disk unfail command.