Netapp NS0-093 - NetApp Accredited Hardware Support Engineer

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Booting the backup image may result in an outdated version of ONTAP, not the desired version.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

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C. Using outdated disk firmware

Explanation:Outdated disk firmware can cause performance issues, drive failures, or incorrect handling of I/O operations, potentially leading to WAFL inconsistencies.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.

If a disk is marked as failed, the Failure Byte on the disk indicates that the disk has been flagged for failure. This can be cleared using the following methods:

What it does:Physically remove the disk from the shelf and reseat it. This action can trigger the system to re-evaluate the disk's status and clear the Failure Byte if the failure was transient or due to connection issues.

1. Reseat the Disk

What it does:Using the disk unfail command in maintenance mode clears the Failure Byte and returns the disk to service.

Command Example:

2. Unfail the Diskdisk unfail

A. Power cycle the disk shelf:

Power cycling the shelf may clear other transient hardware issues but does not specifically clear the Failure Byte.

C. Update the disk firmware:

While updating firmware can prevent future issues, it does not address disks already marked as failed.

Why Other Options Are Incorrect:

NetApp "Disk Maintenance Guide" explains procedures to address failed disks.

The "ONTAP Command Reference" covers the disk unfail command for clearing the Failure Byte.

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.

If the root volume runs out of space, it can cause operational issues and require recovery.

The root volume must always have sufficient space for system logs, configuration files, and core dumps.

1. Root Volume Ran Out of Space:

When a mainboard is replaced, the system configuration stored in the root volume may need to be restored or recovered.

2. Mainboard Was Replaced Following an NMI Panic:

C. Root volume migrate was performed:

Root volume migration is a normal operation and does not typically cause the need for root volume recovery.

D. The cluster configuration is out of sync on the volume:

While this can cause configuration issues, it does not directly lead to root volume recovery.

Why Other Options Are Incorrect:

"ONTAP Root Volume Management Guide" explains scenarios leading to root volume issues and recovery procedures.

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.

ï‚· 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.

ï‚· 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.

ï‚· 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.

ï‚· 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.

ï‚· 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.

ï‚· 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.

ï‚· Steps to Resolve:

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

Example: storage disk assign -disk -owner

ï‚· 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.

For an automatic takeover to occur in an HA pair, the following conditions must be met:

The HA pair uses mailbox disks to coordinate and ensure that both nodes have consistent cluster state information.

If the mailbox disks are not reachable, the takeover process cannot proceed.

1. Mailbox Disks Must Be Reachable:

The nodes in an HA pair continuously mirror NVRAM data to ensure that writes are protected.

If NVRAM is not synchronized, the takeover cannot safely handle active workloads.

2. NVRAM Must Be Synchronized:

A. The combined utilization of both nodes must be less than 100%:

This is not a requirement for automatic takeover. ONTAP can handle higher utilization during failover scenarios.

B. The cluster network must be available:

While the cluster network is critical for normal operation, takeover can still occur if the cluster network is unavailable, as long as the HA interconnect is operational.

Why Other Options Are Incorrect:

NetApp "ONTAP High Availability Guide" outlines the requirements for automatic takeover in HA pairs.

"ONTAP NVRAM Synchronization and Failover Guide" explains NVRAM mirroring requirements.

References: