NS0-093 NetApp Accredited Hardware Support Engineer Questions and Answers

 Explanation of RAID Label Versions:

Disks in ONTAP systems contain metadata known as RAID labels. These labels store critical information such as ownership, aggregate membership, and versioning.

The error indicates a mismatch between the RAID label version on the disk and the supported versions of the ONTAP system.

 Why Option D Is Correct:

If a disk has a RAID label created by a newer version of ONTAP (e.g., version 16) and is then inserted into a system running an older version of ONTAP (e.g., supporting versions 14-15), the label will not be recognized.

This mismatch causes ONTAP to reject the disk.

 Resolution:

Upgrade the ONTAP version to match the RAID label on the disk.

Alternatively, zero the disk to reset its RAID label, but this will erase all data on the disk.

 NetApp Reference Documentation:

The "ONTAP Disk Management Guide" and "ONTAP Compatibility Matrix" explain RAID label versions and compatibility issues when moving disks between ONTAP systems.

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:

Key Details:arduino

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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:

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

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

1. Disconnect the cable chains from the chassis

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.

2. Evacuate all drives in the drawer

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.

Why Other Options Are Incorrect:

"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.

References:

 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.

 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.

 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.

 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".

 NetApp Reference Documentation:

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

A. NVMEM battery

Explanation:The NVMEM (Non-Volatile Memory) battery is a critical component for retaining data in case of a power failure. It is classified as a Field Replaceable Unit (FRU) in an AFF A220 system.

Replacement Notes:

Replacement can be performed by field engineers.

The system will typically alert you when the battery requires replacement.

B. mSATA boot device

Explanation:The mSATA (mini-SATA) boot device contains the ONTAP operating system and is also a FRU in the AFF A220. It is critical for the system's boot process and can be replaced if it becomes faulty.

Replacement Notes:

Boot devices are easily replaceable while ensuring ONTAP is reinstalled on the new device.

Why the Other Options Are Incorrect:

C. NVMe Flash Cache feature:

Incorrect. NVMe Flash Cache is not a physical FRU but a feature for accelerating read performance. It is implemented via software and NVMe-based SSDs, which are not specifically field replaceable in AFF A220.

D. Chassis fan:

Incorrect. The AFF A220 does not classify chassis fans as FRUs. These are usually part of the cooling system, but their replacement may require system shutdown or is integrated into the design.

References:

NetApp Hardware Documentation: AFF A220 Component Replacement Guide.

NetApp Knowledge Base: Articles on replacing NVMEM batteries and mSATA boot devices.

Reverting to a previous ONTAP version requires careful preparation because ONTAP upgrades often introduce irreversible changes. To successfully revert, the following actions are needed:

C. Reinstall your boot media and install ONTAP 9.5 software

Explanation:You need to reinstall the older version of ONTAP (9.5) on the boot media because the current version (9.7) has been installed as part of the upgrade. The reinstallation ensures that the system boots with ONTAP 9.5.

Steps:

Boot the node into maintenance mode.

Perform the reinstallation using the appropriate ONTAP 9.5 image.

D. Wipe your config and restore from backup

Explanation:A revert requires wiping the configuration because ONTAP upgrades may have made changes to the cluster configuration or WAFL metadata. Restoring the configuration from a backup ensures consistency with the older ONTAP version.

Steps:

Back up the current cluster configuration before proceeding.

Use the restored backup after the revert is complete to reconfigure the system.

Why the Other Options Are Incorrect:

A. Revert from ONTAP 9.7 software to ONTAP 9.6 software and then to ONTAP 9.5 software:

Incorrect. ONTAP reverts must directly target the desired version. You cannot perform multi-step reverts.

B. Delete all Snapshot copies from the past two days:

Incorrect. Deleting Snapshot copies is not a prerequisite for reverting ONTAP. While older Snapshot copies might not be compatible with the reverted version, they do not need to be deleted before the revert.

References:

NetApp Documentation: ONTAP Upgrade and Revert Procedures.

NetApp Knowledge Base: Steps for reinstallation and configuration restoration during a revert.

Description:

L1 WDR is a hardware-initiated reset that occurs when the system detects an unrecoverable error or lockup lasting 0.5 seconds.

Key Characteristics:

It performs a hard reset, meaning the system immediately reboots without creating a core dump.

1. L1 Watchdog Reset (WDR):

Description:

L2 WDR is initiated when the system fails to recover from a critical fault after 2 seconds.

Key Characteristics:

It requests a core dump to capture the system state for diagnostic purposes before performing a reset.

2. L2 Watchdog Reset (WDR):

B. L1 WDR is initiated after 0.5 seconds from the event:

This is incorrect because L1 WDR performs a hard reset and does not initiate after 2 seconds.

C. L1 WDR performs a soft reset:

This is incorrect because L1 WDR performs a hard reset, not a soft reset.

Why Other Options Are Incorrect:

"ONTAP Panic Analysis Guide" describes the behavior and timing of L1 and L2 WDR events.

NetApp Support documentation on system resets explains the differences between L1 and L2 watchdog resets.

References:

If the ENVIRONMENT section of the latest MANAGEMENT LOG AutoSupport message is empty, the reason can typically be found in the AUTOSUPPORT-BUDGET.XML file. This file contains information about AutoSupport resource allocation, including what sections were processed and any limits that were hit.

AUTOSUPPORT-BUDGET.XML:

This file provides a summary of the resources (budget) allocated for different AutoSupport sections.

If the ENVIRONMENT section is missing or empty, the AUTOSUPPORT-BUDGET.XML file will indicate whether it was skipped due to resource constraints or configuration limits.

Why Other Sections Do Not Apply:

B. HEADERS: This section only contains metadata about the AutoSupport message, such as timestamps and node details. It does not explain missing sections.

C. AUTOSUPPORT-HISTORY.XML: This file tracks the history of AutoSupport messages but does not provide information about missing sections.

D. MANIFEST.XML: This file lists the contents of the AutoSupport bundle but does not provide details on why a specific section is empty.

Key Details:

"ONTAP AutoSupport Troubleshooting Guide" explains the role of the AUTOSUPPORT-BUDGET.XML file in diagnosing missing or incomplete AutoSupport sections.

References:

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:

 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.

 Command Syntax for Downloading ONTAP Image:

The cluster image package get command is used to download the ONTAP image from a specified URL to the cluster's image repository.

The syntax requires the –url parameter followed by the full URL of the image file.

 Why Option C Is Correct:

This command syntax directly downloads the image from the local web server at http://192.168.10.10/ to the ONTAP cluster repository.

Other options either refer to incorrect commands or unsupported URLs.

 NetApp Reference Documentation:

The "ONTAP Software Upgrade Guide" provides the exact command and steps for downloading ONTAP images via HTTP or FTP.

 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.

 Functionality of RAID Error Propagation (REP):

RAID Error Propagation (REP) ensures that errors on the disk layer, such as unrecoverable read errors, do not propagate as inconsistencies into the WAFL (Write Anywhere File Layout) metadata layer.

WAFL is designed to manage data blocks, and if an error occurs on a user data block, WAFL can identify and handle it gracefully without flagging an inconsistency.

 Why Option A Is Correct:

REP ensures that errors on a user data block are isolated and do not trigger WAFL inconsistencies. Instead, the error is handled at the RAID layer or higher without corrupting metadata.

This design provides a robust mechanism to protect against data integrity issues caused by disk errors.

 NetApp Reference Documentation:

Refer to the "ONTAP Storage Management Guide" and the "NetApp RAID Guide," which explain how RAID and WAFL interoperate and how REP is implemented.

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: