NS0-093 NetApp Accredited Hardware Support Engineer Questions and Answers

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:

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:

When a volume is deleted in a NetApp ONTAP system, it is placed in the Volume Recovery Queue. By default, the volume remains in this recovery queue for 12 hours before being permanently deleted. This allows administrators to recover mistakenly deleted volumes within the set retention period.

Explanation of Default Behavior:

Volume Recovery Queue:

This is a feature in NetApp ONTAP that acts as a safety mechanism, providing a grace period for recovering deleted volumes.

The default retention period for volumes in the recovery queue is 12 hours, as confirmed by the NetApp KB: "How to use the Volume Recovery Queue."

How to Recover a Deleted Volume:

Administrators can recover a deleted volume as long as it remains in the recovery queue and the retention period has not expired.

Use the ONTAP CLI command:

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cluster::> volume recovery-queue recover -vserver -volume

This command restores the volume back to its original state.

How to Check the Volume Recovery Queue:

To view volumes in the recovery queue and their expiration times, use:

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cluster::> volume recovery-queue show

Changing the Default Retention Period:

While the default period is 12 hours, it can be adjusted by administrators to fit specific organizational requirements. This is done via system settings or policies.

Why the Other Options Are Incorrect:

B. 48 hours: Incorrect. The default retention period is not 48 hours; it is 12 hours by default.

C. 72 hours: Incorrect. While a custom configuration could allow this, it is not the default.

D. 24 hours: Incorrect. Although this was previously thought to be the default, NetApp documentation explicitly states it is 12 hours.

References:

NetApp Knowledge Base Article: "How to use the Volume Recovery Queue".

NetApp ONTAP Documentation: Volume Recovery and Data Management Procedures.

 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 -owner

 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.

To troubleshoot the root cause of an unexpected controller reboot, the following tools are commonly used:

What it does:Provides monitoring and performance data for the ONTAP cluster, including historical event logs that may help identify the root cause of a reboot.

1. Active IQ Unified Manager

What it does:The CLI allows you to gather logs and status information directly from the affected node. Commands like event log show and system core are essential for identifying the reason behind the reboot.

2. ONTAP CLI

B. Active IQ Digital Advisor:

This tool focuses on predictive analytics and proactive recommendations, not troubleshooting unexpected reboots.

D. ONTAP Mediator:

This tool is used for managing MetroCluster configurations, not for troubleshooting reboots.

E. Active IQ Config Advisor:

This tool checks for configuration best practices but does not provide detailed logs or reboot diagnostics.

Why Other Options Are Incorrect:

NetApp "ONTAP System Management Guide" emphasizes the use of Unified Manager and CLI for troubleshooting system issues.

References:

The following ONTAP systems support both SSD and SAS disks:

Description:

The FAS2750 is part of NetApp's hybrid storage array product line.

It supports both SSDs for performance tiers and SAS disks for capacity tiers, making it suitable for mixed workloads.

1. FAS2750

Description:

The FAS8200 is an enterprise-level storage system that also supports hybrid configurations with both SSD and SAS drives.

This system is designed to handle high performance and capacity needs.

2. FAS8200

A. AFF C190:

The AFF C190 is an all-flash system and only supports SSDs. It does not support SAS disks.

C. AFF A220:

Like the AFF C190, the AFF A220 is also an all-flash system that supports SSDs only.

Why Other Options Are Incorrect:

NetApp "Hardware Universe" confirms drive support for FAS and AFF systems.

NetApp product documentation details supported disk types for hybrid and all-flash systems.

References:

When a node fails to boot and loads the previous version of ONTAP, it usually indicates that the primary boot location is incorrect. To resolve this:

Enter the LOADER Prompt:

Interrupt the boot process to access the LOADER prompt.

Set the Primary Kernel URL:

Use the following command:

Steps to Boot the Correct ONTAP Version:setenv GX_PRIMARY_KERNEL_URL

Boot the Node:

Run the boot command to load the correct version.

B. From the loader prompt of nodeA1, run boot_backup:

Booting the backup image may result in an outdated version of ONTAP, not the desired version.

C. From the clustershell of the partner, run system node image modify:

Modifications to the ONTAP image must be done from the LOADER prompt, not the clustershell.

D. From the clustershell of nodeA1, run system node image modify:

NodeA1 cannot load ONTAP, so this command cannot be run.

Why Other Options Are Incorrect:

"ONTAP System Boot Guide" explains how to resolve boot issues using the LOADER prompt.

NetApp documentation on environment variables includes the use of GX_PRIMARY_KERNEL_URL.

References:

To ensure that POST (Power-On Self-Test) runs on boot, the setenv POST=true command is used at the LOADER prompt. This command enables the system to perform POST diagnostics before proceeding with the boot process.

POST Purpose: POST checks system hardware components (such as memory, disk, and controllers) for faults before loading the ONTAP kernel.

How to Use:

At the LOADER prompt, type:

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setenv POST=true

Save the configuration and reboot the system.

B. bye:

This command restarts the system but does not ensure that POST runs on boot.

C. boot_diag:

This command boots the system into diagnostic mode but is not directly related to enabling POST on boot.

D. boot_ontap:

This command boots ONTAP but skips POST if it is not explicitly enabled.

Why Other Options Are Incorrect:

NetApp "ONTAP System Boot and Recovery Guide" describes setenv POST=true for enabling POST diagnostics.

References:

 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.

 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.

 NetApp Reference Documentation:

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

 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.

When using wafliron to repair WAFL inconsistencies on an aggregate, the aggregate becomes available after Phase 4 of the wafliron process is complete.

Phase 1: Initial scan to identify inconsistencies.

Phase 2: Corrects directory and inode structure issues.

Phase 3: Repairs blocks and metadata.

Phase 4: Completes final repairs and verification, after which the aggregate can be made available.

Phases of wafliron:

A. when the administrator manually onlines the aggregate:

The aggregate cannot be manually brought online until wafliron completes Phase 4.

B. when wafliron is started:

Starting wafliron does not make the aggregate available; repairs need to be completed first.

D. after the mounting phase of wafliron is complete:

WAFLiron does not have a specific "mounting phase." Mounting happens after Phase 4 completes.

Why Other Options Are Incorrect:

"NetApp WAFLiron Troubleshooting Guide" explains the availability of the aggregate after Phase 4.

NetApp Support documentation outlines the phases of wafliron and aggregate recovery.

References:

When a node panics in ONTAP, a kernel core file is generated. This core file contains information about the kernel's state at the time of the panic and is essential for debugging system crashes.

A kernel core file is produced during a node panic to capture information about the kernel, memory, and processes that led to the crash.

The core file is stored on the root aggregate by default and can be uploaded to NetApp Support using the autosupport invoke-core-upload command.

Key Details:

A. mgwd core:

This is related to the Management Gateway daemon, which handles management traffic. It does not generate a core file during a panic.

B. user space core:

User space cores are generated for processes running in user space, not for kernel panics.

C. sync core:

Sync cores refer to synchronized cores for debugging but are not the primary type generated during a node panic.

Why Other Options Are Incorrect:

"ONTAP Panic Troubleshooting Guide" specifies kernel core files as the output of a node panic.

"ONTAP Core File Management Guide" details the handling of kernel core files after a crash.

References:

 Analyzing the Error in the Event Log:

The log entry indicates a medium error on a disk, suggesting an unrecoverable read issue.

While the RAID subsystem attempts to reconstruct unreadable data, this error might indicate a firmware issue or a compatibility problem with the disk.

 Why Reviewing Firmware and Known Issues Is Important:

Medium errors can sometimes result from outdated or incompatible firmware.

By reviewing firmware release notes and known issues for the disk model (NETAPP X381_HLBRE10TSDB in this case), you can identify if this is a known issue and resolve it by updating the firmware.

 Other Options:

Sanitize the disk (Option A): Not relevant here, as sanitization is used for secure data erasure.

Reseat the disk (Option B): Useful for addressing hardware seating issues, but not the first step here.

Diskcopy to a spare (Option D): This is a last-resort recovery step and not the primary action.

 NetApp Reference Documentation:

"ONTAP Disk Management Guide" and "Disk Firmware Release Notes" detail how to handle medium errors and update firmware.

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

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.

1. wafl_check

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.

2. wafliron

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.

Why Other Options Are Incorrect:

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

NetApp Support documentation provides guidelines for recovering inconsistent aggregates.

References: