NS0-093 NetApp Accredited Hardware Support Engineer Question and Answers

ï‚· Purpose of the diskcopy Command:

The diskcopy command is used in the ONTAP nodeshell environment to perform a low-level sector-by-sector copy of data from one disk to another. This is typically used during data recovery or diagnostics.

ï‚· How It Works:

The command copies all sectors from the source disk to the destination disk without any regard for file system or metadata structures.

It is commonly used when replicating the exact state of a failing disk to a spare for further analysis or recovery.

ï‚· Key Notes:

The destination disk must be of the same or larger capacity than the source disk.

The operation is typically disruptive and not suitable for production use.

ï‚· NetApp Reference Documentation:

Found in the "ONTAP Command Line Manual" for nodeshell utilities. The diskcopy process is highlighted as a low-level disk cloning operation.

To collect shelf logs for a DS4246 shelf in an ONTAP 9.12.1 system, you must invoke a diagnostic AutoSupport specifically targeting the storage subsystem. This action ensures that detailed storage logs, including shelf logs, are included in the AutoSupport bundle.

Use the following command:

Steps to Collect Shelf Logs:bash

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system node autosupport invoke -node -type diagnostic -subsystem storage

Replace with the name of the node experiencing the issue.

This command generates an AutoSupport message that includes logs related to storage subsystems, such as disk shelves and adapters.

Provide the AutoSupport case number to NetApp Support for further analysis.

A. Provide the output of the nodeshell command rdfile /etc/log/shelflog:

While this command allows manual reading of shelf logs, it is not a recommended or comprehensive approach for collecting logs for NetApp Support cases.

B. Invoke an AutoSupport of type all using Active IQ Unified Manager:

This action generates a generic AutoSupport bundle, which may not include detailed shelf logs unless explicitly targeted.

D. Invoke a diagnostic AutoSupport with the subsystem log_files:

The log_files subsystem targets general system logs, not storage-specific logs like shelf logs.

Why Other Options Are Incorrect:

"ONTAP 9 AutoSupport and Diagnostics Guide" outlines the use of the subsystem storage option for collecting shelf logs.

The "Troubleshooting Storage Subsystems" documentation specifies diagnostic AutoSupport as the method for gathering shelf-related logs.

References:

To determine the root cause of an unexpected node failure using the Service Processor (SP), the following commands are helpful:

What it does:Displays recent events logged by the Service Processor. This includes hardware failures, environmental alerts, or other events that may have caused the node failure.

Example Usage:

1. event log showevent log show

What it does:Shows information about any core dumps that were generated during the failure. A core dump provides a snapshot of the system state at the time of the failure, which can be analyzed to identify the root cause.

2. system coresystem core

A. sp status –d:

This command provides status information about the Service Processor itself but does not help diagnose the root cause of the node failure.

C. system log:

This is not a valid Service Processor command.

Why Other Options Are Incorrect:

NetApp "Service Processor Diagnostics Guide" details commands such as event log show and system core for troubleshooting node failures.

References:

ï‚· 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.

ï‚· Step 1: Remove the Disk from the Failed Disk Registry

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

ï‚· Step 2: Use the Disk Unfail Command

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

ï‚· 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.

ï‚· 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.

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

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.

1. Two disks failing and a block error during reconstruction

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.

2. Two disks failing within seconds of each other

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.

Why Other Options Are Incorrect:

"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.

References:

ï‚· Reverting to a Previous ONTAP Version:

Reverting ONTAP software requires specific procedures and is only supported if the ONTAP version being reverted to is compatible with the current cluster configuration.

ï‚· Why the Netboot Procedure Is Used:

The netboot process loads the desired ONTAP version directly into memory from a network location and reinitializes the system.

This method is used when a full software revert is required and is often necessary for downgrades to a version that cannot be directly reverted to from the running ONTAP version.

ï‚· Key Notes:

A direct revert is not supported from ONTAP 9.7 to ONTAP 9.5 using standard methods due to system metadata changes.

Always verify compatibility using the "ONTAP Software Version Interoperability Matrix".

ï‚· NetApp Reference Documentation:

Refer to the "ONTAP Revert/Downgrade Guide" for specific instructions on using the netboot procedure.

In a clustered ONTAP system, write requests are acknowledged to the client only after they are securely stored in NVRAM on both the local node and its HA (High Availability) partner.

This ensures redundancy and data protection in case of a node failure.

Write Acknowledgment in NetApp ONTAP:

A. when the write is present in the local node RAM and NVRAM:

Writes are not acknowledged until the HA partner also stores the data in its NVRAM.

B. when the write has been flushed to disk:

Writes are acknowledged before they are written to disk, as NVRAM ensures durability.

D. when the write has been flushed from NVRAM to RAM:

Data is not acknowledged based on RAM; NVRAM on both nodes is the requirement.

Why Other Options Are Incorrect:

NetApp’s "ONTAP Write I/O Processing Guide" explains the role of NVRAM and HA in write acknowledgment.

"Data Protection in ONTAP" highlights the synchronization of NVRAM between HA partners.

References:

ï‚· 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.

ï‚· 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.

ï‚· 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.

To determine whether an aggregate is WAFL (Write Anywhere File Layout) inconsistent, the following two commands can be used:

What it does:This command directly checks the WAFL consistency status of the specified aggregate. If an aggregate is WAFL inconsistent, it will report the inconsistency in the output.

How to use:

Run the command: wafiron show (replace with the name of the aggregate).

Look for indications of WAFL inconsistency in the output.

Why it's relevant:The wafiron utility is specifically designed to provide WAFL status and diagnostics. It is the most accurate and direct way to confirm whether an aggregate is inconsistent.

References:

"WAFL Troubleshooting Guide" from NetApp highlights the wafiron show command as a primary tool for checking aggregate consistency.

1. wafiron show

What it does:This command displays RAID information for all aggregates on the specified node. If an aggregate is WAFL inconsistent, it will be explicitly mentioned in the output.

How to use:

Run the command: node run –node sysconfig –r.

Check the output for the phrase "WAFL inconsistent" under the corresponding aggregate.

Why it's relevant:This command provides additional context, such as the RAID group details, which can help understand whether the inconsistency is isolated or part of a larger issue.

References:

"ONTAP CLI Commands Guide" specifies sysconfig –r as a method to verify aggregate status, including WAFL consistency.

2. node run –node sysconfig –r

C. storage aggregate show:

This command displays aggregate configuration and usage information but does not report WAFL inconsistency.

D. node run –node <node> sysconfig –a:

While this command shows detailed hardware configuration information, it does not include WAFL consistency status for aggregates.

Why Other Options Are Incorrect:

To trigger an AutoSupport message in ONTAP, the following commands are valid:

What it does:This command manually triggers a complete AutoSupport message of type "all." This includes logs and system information from all subsystems.

How to use:

Run the command: autosupport invoke –node –type all

Replace with the name of the node for which you want to generate the AutoSupport message.

Why it's relevant:This is the primary method for triggering a full AutoSupport message manually. It is commonly used during troubleshooting to provide comprehensive system data to NetApp Support.

1. ::> autosupport invoke –node –type all

What it does:This command is specifically used to upload core files (e.g., kernel or user space cores) from a node to NetApp Support for analysis.

How to use:

Run the command: autosupport invoke-core-upload –node .

Replace with the name of the node for which you want to upload core files.

Why it's relevant:If there is a system panic or other critical issue, this command ensures that core files are included in the AutoSupport message for detailed analysis.

2. ::> autosupport invoke-core-upload –node

A. ::> autosupport history show-upload-details –node <nodename>:

This command displays the history of AutoSupport uploads but does not trigger a new AutoSupport.

B. ::> system node coredump upload –node <nodename>:

This command uploads coredumps directly to a support server but does not trigger an AutoSupport message.

Why Other Options Are Incorrect:

"ONTAP 9 AutoSupport Configuration Guide" confirms autosupport invoke as a valid command to trigger AutoSupport messages.

"ONTAP CLI Reference Manual" specifies autosupport invoke-core-upload for core file uploads.

References:

Description:

When a negotiated takeover occurs (e.g., for maintenance or upgrades), NVRAM data is replayed by the HA partner to ensure no data is lost.

Relevance:

This ensures that all pending writes are safely processed by the partner node.

1. During a Negotiated Takeover:

Description:

If a node loses power unexpectedly, the HA partner replays the mirrored NVRAM data to protect active write operations.

2. When the Node Loses Power:

A. after triggering a sync core:

Triggering a sync core does not involve NVRAM replay; it captures the system state for debugging.

B. when a node is halted:

Halting a node does not trigger NVRAM replay unless it is part of a negotiated takeover.

Why Other Options Are Incorrect:

"ONTAP High Availability Guide" explains NVRAM mirroring and replay during failover scenarios.

References:

A. Ignoring NetApp Active IQ health risks

Explanation:NetApp Active IQ provides proactive monitoring and alerts for system health risks, including risks related to WAFL inconsistencies. Ignoring these alerts can lead to unresolved issues such as metadata corruption, hardware failures, or system misconfigurations, increasing the chances of WAFL inconsistencies.

Examples of Active IQ Risks:

Disk health warnings.

High write latency or metadata bottlenecks.

Aggregates running out of space.

C. Using outdated disk firmware

Explanation:Outdated disk firmware can cause performance issues, drive failures, or incorrect handling of I/O operations, potentially leading to WAFL inconsistencies. Disk firmware updates often include fixes for critical issues that improve reliability and prevent data corruption.

Importance:Keeping firmware updated ensures compatibility with ONTAP and minimizes risks of disk-level errors that can propagate to WAFL.

Why the Other Options Are Incorrect:

B. Constantly running at high load:

Running at high load can impact performance but does not directly cause WAFL inconsistencies. WAFL is designed to handle high I/O loads efficiently.

D. Upgrading frequently:

Frequent upgrades, when performed correctly, do not increase the chances of WAFL inconsistencies. However, improperly executed upgrades or skipping recommended steps might introduce risks.

References:

NetApp Knowledge Base: Articles on Active IQ health checks and disk firmware management.

ONTAP System Administration Guide: Recommendations for preventing WAFL inconsistencies.

When replacing a boot device on a FAS8300 system and using a USB memory stick for recovery or installation, the external USB port must be explicitly enabled. This is done through the setenv command in the boot environment.

Reboot the system and interrupt the boot process to access the bootloader prompt.

At the bootloader prompt, use the following command:

Steps to Enable the External USB Port:arduino

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setenv usbport_enabled true

Save the configuration and proceed with the boot process.

B. You need to use ONTAP 9.11 or later software:

ONTAP 9.10P6 fully supports external USB recovery. There is no need to upgrade to ONTAP 9.11 for this functionality.

C. Add the boot device before the BIOS is loaded:

While the USB device must be inserted during the boot process, this alone will not enable access unless the port is enabled via setenv.

D. The external USB port is not activated on NetApp systems:

This is incorrect. The external USB port is supported but must be explicitly enabled in the bootloader environment.

Why Other Options Are Incorrect:

NetApp Hardware Installation Guide for FAS8300 systems outlines the steps for enabling the USB port during recovery.

"ONTAP Boot Troubleshooting Guide" specifies the use of the setenv command to activate USB ports.

References:

ï‚· What Is a Watchdog Timeout?

The watchdog is a software or hardware mechanism that monitors the system’s health and ensures it is operating correctly.

If the system fails to respond or update the watchdog timer within the specified time, the watchdog triggers a system panic to avoid further corruption or damage.

ï‚· Cause of Watchdog Timeout:

This usually occurs due to:

A hardware failure (e.g., CPU or memory issue).

A software bug causing a system hang or crash.

The panic ensures the system stops operation to preserve data integrity and aid in troubleshooting.

ï‚· NetApp Reference Documentation:

"ONTAP Troubleshooting Guide" and "Core Dump Analysis Guide" provide details on interpreting watchdog timeouts and recommended actions.