Network Appliance NS0-093 Practice Test - Questions Answers, Page 2

A NetApp WAFL (Write Anywhere File Layout) inconsistency in a RAID-DP aggregate could occur in the following scenarios:

1. Two disks failing and a block error during reconstruction

Why this causes inconsistency:

RAID-DP is designed to handle up to two concurrent disk failures. However, if a block error occurs during the reconstruction process (e.g., unreadable data on the surviving disks), the RAID group cannot rebuild the lost data, leading to WAFL inconsistencies.

2. Two disks failing within seconds of each other

Why this causes inconsistency:

If two disks in the same RAID group fail nearly simultaneously (before the RAID-DP can reconstruct data from the first failed disk), the system cannot recover the data, resulting in WAFL inconsistencies.

Why Other Options Are Incorrect:

B . rebooting a node during a disk reconstruction:

Rebooting a node does not cause WAFL inconsistency because ONTAP ensures that RAID reconstructions resume upon reboot without data loss.

D . both party disks failing:

This is not a valid RAID-DP term.

'WAFL and RAID-DP Operations Guide' explains failure scenarios that could cause inconsistencies.

NetApp's 'Troubleshooting RAID Groups and Aggregates' covers recovery procedures for double-disk failures and reconstruction errors.

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.

To invoke AutoSupport in ONTAP, the following tools can be used:

1. CLI (Command Line Interface)

How to use: Run the command:

python

Copy code

autosupport invoke -node <nodename> -type all

This triggers AutoSupport to collect and send logs and system information.

2. NetApp Active IQ website

How to use: Log in to the Active IQ portal and use its interface to request an AutoSupport message from the connected ONTAP systems.

Why Other Options Are Incorrect:

A . NetApp Cloud Insights:

This tool is used for monitoring and performance analysis, not for triggering AutoSupport messages.

D . the SmartSolve tool:

SmartSolve is used for case resolution guidance but does not invoke AutoSupport.

'ONTAP AutoSupport Guide' provides instructions for invoking AutoSupport via CLI and Active IQ.

To diagnose a PCI/NMI error and collect logs, use the following commands:

1. pelog --a --g=2

What it does: This command collects PCI error logs, including detailed information about PCI devices and the errors that caused the panic.

How to use: Run the command from the nodeshell to capture the required PCI log entries.

2. rdfile /mroot/etc/log/SSRAM

What it does: This command reads the SSRAM log file, which contains low-level error information related to PCI and other hardware subsystems.

How to use: Run the command to view the log entries directly for detailed troubleshooting.

Why Other Options Are Incorrect:

B . show pci --v:

While this command displays PCI device information, it does not provide detailed error logs.

D . event log show:

This displays event log entries but does not contain the specific PCI or NMI-related logs required for diagnosing the panic.

'ONTAP Hardware Troubleshooting Guide' lists pelog and SSRAM as tools for analyzing PCI errors.

'ONTAP Panic Analysis Guide' emphasizes the importance of collecting detailed hardware logs.

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.

Best Practices for SAS Cabling in AFF A700 Systems:

The AFF A700 system has built-in SAS ports (e.g., 2a and 2b) as well as additional SAS ports on optional SAS cards.

To ensure high availability and redundancy, it is recommended to distribute SAS connections across multiple SAS ports from different controllers or slots.

Why Port 2a and 9a Are Recommended:

Port 2a is a built-in SAS port on the AFF A700 system.

Port 9a belongs to the additional SAS card in slot 9.

By connecting the stack using 2a and 9a, you utilize different SAS domains (built-in controller ports and add-on card ports), providing both path redundancy and load balancing.

NetApp Reference Documentation:

'NetApp Hardware Universe' and 'ONTAP Hardware Installation Guide' highlight that SAS cabling for redundancy should leverage different ports, including those from separate SAS controllers or add-on cards.

NetApp's best practice guidelines suggest avoiding connections to the same SAS controller or port group for critical stacks.

Understanding 'Container Type: Unknown' in Disk Show Output:

The 'unknown' container type typically indicates that the disk is not properly configured or recognized by ONTAP.

This status often occurs when a disk does not have an owner assigned.

Root Cause:

For a disk to be used in an ONTAP system, it must be owned by a member of the high-availability (HA) pair.

If no ownership is assigned, the disk will not be initialized, resulting in an 'unknown' container type.

Steps to Resolve:

Use the disk assign command to manually assign ownership of the disk.

Example: storage disk assign -disk <disk_name> -owner <node_name>

NetApp Reference Documentation:

'ONTAP Disk Management Guide' explicitly states that unowned disks report 'unknown' container type until they are assigned to a node.

This is further detailed in the 'ONTAP Troubleshooting Guide' under disk configuration issues.

Overview of IOM 12 Module:

The IOM 12 module is used in NetApp storage shelves for SAS connectivity.

Key Features of IOM 12:

SAS Ports: The IOM 12 module has four SAS ports (two IN and two OUT) to support daisy-chaining of shelves and provide redundancy.

ACP (Alternate Control Path): The IOM 12 includes an Ethernet port for ACP, which is used for out-of-band management and monitoring of the storage shelves.

Elimination of Other Options:

Option A is incorrect because the module has four SAS ports, not two.

Option C is incorrect because the module does include an Ethernet port for ACP.

NetApp Reference Documentation:

'NetApp Hardware Universe' lists the specifications of the IOM 12 module, including its SAS and ACP capabilities.

The 'ONTAP Shelf Installation Guide' discusses ACP and its role in shelf management.

Upgrade Considerations for Disk and CPU Utilization:

During an ONTAP upgrade, it is critical to ensure the system has sufficient resources to handle the upgrade process without impacting normal operations.

Recommended Threshold:

NetApp recommends that both disk and CPU utilization should be below 70% before initiating an upgrade. This ensures that there is enough headroom for the upgrade operations and avoids performance degradation.

Steps to Verify Utilization:

Use the system node show -fields cpu command to check CPU usage.

Use the storage aggregate show -fields used command to check aggregate disk utilization.

NetApp Reference Documentation:

'ONTAP Upgrade and Maintenance Guide' specifies the 70% threshold for disk and CPU usage during upgrade planning.

The 'ONTAP Performance Management Guide' provides methods for monitoring system resource utilization.