Network Appliance NS0-093 Practice Test - Questions Answers, Page 4

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

1. Mailbox Disks Must Be Reachable:

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.

2. NVRAM Must Be Synchronized:

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.

Why Other Options Are Incorrect:

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.

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

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

1. Root Volume Ran Out of Space:

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.

2. Mainboard Was Replaced Following an NMI Panic:

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

Why Other Options Are Incorrect:

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.

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

When a WAFL inconsistency is detected, the first step is to stabilize the system before attempting any repairs or recovery.

Steps to Handle WAFL Inconsistency:

Stabilize the System:

Ensure that the system is not experiencing ongoing hardware or software issues.

Avoid making changes to the affected aggregate or volume until the system is stable.

Assess the Impact:

Determine which aggregates or volumes are affected and the severity of the inconsistency.

Why Other Options Are Incorrect:

A . Run wafliron:

Running wafliron should only be done after stabilizing the system and under guidance from NetApp Support.

C . Force offline the affected aggregate:

Forcing an aggregate offline without proper assessment can lead to data loss.

D . Run a dump to null:

Dumping data is not relevant for resolving a WAFL inconsistency.

'NetApp WAFL Troubleshooting Guide' specifies that stabilization is the first step after detecting inconsistencies.

NetApp Support documentation provides guidelines for handling WAFL inconsistencies safely.

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.