Netapp NS0-093 - NetApp Accredited Hardware Support Engineer

ï‚· FRUs on FAS9000 Supporting Replacement Without Takeover:

A (I/O Module): I/O modules can be replaced hot (without takeover) to maintain system uptime during hardware servicing.

D (NVRAM Module): NVRAM modules on FAS9000 can also be replaced without a node takeover, ensuring data integrity during replacement.

ï‚· Why Other Options Are Incorrect:

B (DCPM Module): The DCPM (Data Center Power Management) module is not hot-swappable and requires a node takeover.

C (Caching Module): The caching module is integrated and typically requires a node takeover or power-down for replacement.

ï‚· NetApp Reference Documentation:

Refer to the "NetApp FAS9000 Hardware Service Guide" for supported FRU replacement procedures and operational constraints.

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:

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:

ï‚· 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.

ï‚· 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.

ï‚· 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 NetApp high-availability (HA) configuration, multipath HA ensures redundancy by providing two independent paths from each controller to the connected storage. If the system is currently showing Single-Path HA, it means only one path is operational or connected, which is a potential single point of failure.

To convert the configuration to multipath HA, additional cabling must be configured to establish the second path. For the AFF A220 system, the correct connections are as follows:

Explanation of the Correct Answer:

AFF A220 Port Configuration for HA:

Each controller in an AFF A220 has ports labeled 0a, 0b, 0c, and 0d for connectivity.

In a multipath HA configuration, each controller must have two independent paths to the connected storage via the partner controller's disk shelves.

Correct Cabling for Multipath HA:

Port 0a on both controllers must be connected to the corresponding port (e.g., disk shelf stack or Inter-Switch Link).

Port 0c on both controllers must also be connected to complete the redundant path.

These connections ensure that there are two independent data paths between the controllers and the storage system, providing fault tolerance in case one path fails.

Single-Path HA to Multipath HA:

If the system currently shows Single-Path HA, it is likely that only one set of ports (e.g., 0a and 0b) are cabled.

Adding the additional connections on 0a and 0c establishes the second path required for multipath HA.

Why the Other Options Are Incorrect:

A. 0a and 0b on both controllers should be connected:

This option only connects ports 0a and 0b, which does not establish a multipath HA configuration. Port 0c is also required for redundancy.

C. 0c and 0d on both controllers should be connected:

Connecting only 0c and 0d would leave ports 0a disconnected, failing to establish a proper multipath HA setup. Both 0a and 0c are required.

D. 0a and 0d on both controllers should be connected:

Connecting 0a and 0d is not the standard configuration for multipath HA in an AFF A220 system. Port 0c is part of the required configuration.

How to Verify the Configuration:

Use the following ONTAP command to verify the HA status:

cluster::> storage failover show -fields multipath-ha

This will display whether the system is in multipath HA or single-path HA mode.

Check the port connectivity:

cluster::> network port show -node

References:

NetApp Hardware Installation and Setup Guide for AFF A220.

NetApp Knowledge Base: "Configuring Multipath HA for AFF Systems."

ONTAP 9.x System Administration Guide: "High Availability Configurations."

ï‚· Understanding Single-Path HA vs. Multipath HA:

Single-Path HA indicates that only one path exists between the controllers and the connected shelves, leading to limited redundancy.

Multipath HA requires both controllers to have redundant SAS connections to the shelves.

ï‚· Cabling for Multipath HA in AFF A220 Systems:

To achieve multipath HA, you must connect 0c and 0d on both controllers to the appropriate stack ports on the shelves.

This ensures dual paths for each controller to access the storage shelves.

ï‚· NetApp Reference Documentation:

Refer to the "ONTAP Multipath HA Configuration Guide" and the "NetApp Hardware Installation Guide" for AFF A220 systems for cabling diagrams and best practices.

In a SAS stack of shelves, the connection between the expander and the disk uses a point-to-point topology.

Point-to-Point:

Each SAS disk in a shelf connects directly to the expander using a dedicated channel. This ensures that communication between the disk and expander is independent of other disks, improving performance and reliability.

Why SAS Uses Point-to-Point:

SAS (Serial Attached SCSI) eliminates the shared bandwidth limitations of traditional bus architectures (e.g., arbitrated loop or ring) by dedicating a connection to each device.

Key Details:

A. arbitrated loop:

Arbitrated loop is a topology used in Fibre Channel systems, not SAS.

C. loop:

SAS does not use loop-based communication; this is typical of older technologies like SCSI Parallel Interface (SPI).

D. ring:

Ring topology is not used in SAS stacks.

Why Other Options Are Incorrect:

"NetApp SAS Shelf and Disk Configuration Guide" specifies point-to-point communication between expanders and disks in SAS environments.

References:

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:

ï‚· RAID-TEC Overview:

RAID-TEC (Triple Erasure Coding) is a NetApp RAID technology designed to protect against up to three simultaneous disk failures.

It is ideal for systems with high-density disks or workloads requiring extreme fault tolerance.

ï‚· Why RAID-TEC Is Correct:

RAID-TEC uses triple-parity protection, which provides redundancy against three disk failures, making it more resilient than RAID-DP or RAID 5.

RAID-DP only protects against two disk failures, while RAID 4 and RAID 5 protect against a single failure.

ï‚· NetApp Reference Documentation:

"NetApp RAID and Data Protection Guide" details the differences between RAID-DP and RAID-TEC, highlighting RAID-TEC's ability to tolerate three failures.