NS0-593 Sample Questions Answers

= The NetApp Cloud Volumes ONTAP Release Notes provide the most up-to-date and accurate information about the storage limits for different cloud platforms, licenses, and configurations. The release notes also include details about supported features, known issues, and limitations for each version of Cloud Volumes ONTAP. References = Storage limits - NetApp, Storage limits | NetApp Documentation, Storage limits in AWS | NetApp Documentation, Storage limits in Azure | NetApp Documentation

= The FIFO message before NMI is useful for investigating the issue because it shows the state of the system before the non-maskable interrupt (NMI) was triggered by the L2 watchdog timeout. The FIFO message contains information about the CPU registers, the stack pointer, the instruction pointer, and the last executed instructions. This can help identify the cause of the system hang or deadlock that led to the watchdog reset. The other FIFO messages are not useful because they show the state of the system after the reset or shutdown, which may not reflect the original problem. References = https://kb.netapp.com/onprem/ontap/hardware/Handling_L2_Watchdog_Resets_on_the_FAS8200_and_AFF_A300_platforms

https://docs.netapp.com/us-en/ontap-metrocluster/install-ip/task_sw_config_restore_defaults.html

= The NetApp sanlun command is a tool that returns information about the LUNs mapped to your host, multipathing, and information necessary to create initiator groups. It is part of the Linux Unified Host Utilities package, which also includes other tools to manage NetApp storage, such as failover policies and physical paths. To run the sanlun command, you must install the Host Utilities package on your Linux host. The other options are not relevant for this scenario, as they are either not required or not compatible with the Linux host. References = Install Linux Unified Host Utilities 7.1, SAN Toolkit

• The AUSO feature is a MetroCluster functionality that enables an automatic switchover to the surviving site in the event of a disaster that affects one site1.
• The AUSO feature is only available in MetroCluster FC configurations, which use Fibre Channel (FC) switches and FC-to-SAS bridges to connect the nodes and disk shelves across sites1.
• MetroCluster IP configurations, which use Ethernet switches and network adapters to connect the nodes and disk shelves across sites, do not support the AUSO feature2.
• Instead, MetroCluster IP configurations use the ONTAP Mediator service, which is a software component that monitors the health and connectivity of the MetroCluster nodes and initiates a Mediator-assisted unplanned switchover when a disaster occurs3.
• The Mediator-assisted unplanned switchover is similar to the AUSO feature, but it requires the ONTAP Mediator service to be configured and running on a separate host3.
• Therefore, you would tell your customer that the AUSO feature is not available in MetroCluster IP installations by design, and that they need to use the ONTAP Mediator service instead for disaster recovery. References:
• 1: Understanding MetroCluster data protection and disaster recovery, ONTAP MetroCluster Documentation Center
• 2: Differences among the ONTAP MetroCluster configurations, ONTAP MetroCluster Documentation Center
• 3: Configure the ONTAP Mediator service from a MetroCluster IP configuration, ONTAP MetroCluster Documentation Center

• The mailbox disks are the first two disks of the root aggregate on each node of an HA pair. They store the HA state information and the panic dump files. The mailbox disks are used for communication between the HA partners and for takeover and giveback operations1
• The mailbox destroy local command is used to destroy the mailbox disks on the local node. This command is only available in maintenance mode and should be used with extreme caution. The command is intended for situations where the mailbox disks are corrupted or inaccessible and need to be recreated2
• If the mailbox destroy local command is executed on a node that is in takeover mode, the node will panic with the message “Permanent errors on all HA mailbox disks”. This is because the node will lose the HA state information and the panic dump files of the partner node, and will not be able to communicate with the partner node or perform a giveback operation3
• Therefore, if the motherboard of Node-01 is being replaced, and a takeover was initiated from Node-02, and Node-02 panics showing the string “Permanent errors on all HA mailbox disks”, the most likely cause is that the mailbox destroy local command was executed on Node-02 while in maintenance mode. This is a serious error that can result in data loss and system downtime4

References:

1: ONTAP 9 - High-Availability Configuration Guide - The Open Group 2: ONTAP 9 - Commands: Manual Page Reference - The Open Group 3: How to troubleshoot a “Permanent errors on all HA mailbox disks” panic - NetApp Knowledge Base 4: One node PANIC : Permanent errors on all HA mailbox disks - NetApp Knowledge Base

According to the SAS cabling rules and concepts for shelves with IOM12/IOM12B modules1, one of the goals is to provide a single, easily understood universal algorithm for all SAS products and configurations. One of the rules is that of the two paths to a single disk storage stack from a single node, one should connect to the top and one to the bottom of the storage stack. This ensures maximum possible resilience and minimizes the reliance on controller takeovers. The exhibit shows that both SAS connections from one controller go to the same shelf, which violates this rule and causes the error message. This situation is not normal for a FAS2750 single-node system and can reduce reliability and availability. The cables should be reconnected according to the SAS cabling rules and the controller-to-stack cabling worksheet template for quad-pathed connectivity2. References = SAS cabling rules and concepts - shelves with IOM12/IOM12B modules, SAS cabling issue: Both SAS connections from one controller go to the same shelf, Controller-to-stack cabling worksheet template for quad-pathed connectivity.

The broken disk in Node03 is causing the cluster ring to be offline, which prevents the CIFS SVM from being accessible. The cluster ring is a distributed database that stores cluster configuration information and enables communication between cluster nodes. If the cluster ring is offline, the cluster cannot function properly and the CIFS SVM cannot serve data to clients. The other options are not relevant to the CIFS SVM connectivityissue. References = https://www.netapp.com/support-and-training/netapp-learning-services/certifications/support-engineer/

https://mysupport.netapp.com/site/docs-and-kb

• A Twinax cable is a type of copper cable that is used to connect cluster ports to cluster switches1.
• A cluster port is a network port that is configured for cluster communication and data access2.
• A cluster switch is a network switch that is used to interconnect the nodes in a cluster and provide redundancy and load balancing3.
• A cluster network is a network that enables cluster communication and data access between the nodes in a cluster and external clients4.
• A cluster network can be degraded due to various reasons, such as misconfiguration, malfunction, or excessive link errors on the cluster ports or the cluster switches.
• Link errors are errors that occur on the physical layer of the network, such as CRC errors, length errors, alignment errors, or dropped packets.
• Link errors can indicate a problem with the cable, the switch port, the network interface card (NIC), or the cable connector.
• In this scenario, the alert messages state that the cluster network has degraded and the errors are being generated from Node 2, interface e0b.
• The first step to solve this problem is to replace the Twinax cable between Node 2, interface e0b and the NetApp CN1610 switch, as this could be the source of the link errors.
• Replacing the cable could resolve the issue and restore the cluster network to a healthy state.
• If replacing the cable does not solve the problem, then other steps may be required, such as checking the switch port, the NIC, or the cable connector, or replacing the switch or the motherboard. References:
• 1: Cluster network cabling, ONTAP 9 Documentation Center
• 2: Cluster ports, ONTAP 9 Documentation Center
• 3: Cluster switches, ONTAP 9 Documentation Center
• 4: Cluster network, ONTAP 9 Documentation Center
• [5]: How to troubleshoot CLUSTER NETWORK DEGRADED error messages, NetApp Knowledge Base
• [6]: Cluster network degraded due to high CRC errors on cluster ports, NetApp Knowledge Base

• The error message “wafl.cp.toolong:error” indicates that a WAFL consistency point (CP) took longer than 30 seconds to complete. A CP is a process that flushes the data from the NVRAM buffer to the disk. A long CP can cause latency and performance issues for the system1
• One possible cause for a long CP is excessive SSD load causing the wear leveling to become unbalanced. Wear leveling is a technique that distributes the write operations evenly across the SSD cells to extend the lifespan of the SSD. If some SSD cells are written more frequently than others, the wear leveling will become unbalanced and the SSD performance will degrade2
• Another possible cause for a long CP is an SSD disk performing garbage collection to create a dense data layout. Garbage collection is a process that reclaims the space occupied by invalid or deleted data on the SSD. Garbage collection can improve the write performance and storage efficiency of the SSD, but it can also consume CPU and disk resources and cause long CPs3
• A disk failing or being failed is not a likely cause for a long CP, because the system will automatically mark the disk as failed and remove it from the aggregate. The system will also initiate a disk reconstruction or a RAID scrub to restore the data protection and redundancy4
• There is no evidence that the system has SATA HDDs, so there is no reason to assume that there is excessive SATA HDD load. Moreover, SATA HDDs are usually used for secondary or backup storage, not for primary or performance-sensitive workloads5

References:

1: Are long Consistency Points (wafl.cp.toolong) normal? - NetApp Knowledge Base 2: How to troubleshoot SSD performance issues - NetApp Knowledge Base 3: How to troubleshoot SSD garbage collection issues - NetApp Knowledge Base 4: How to troubleshoot disk failures and replacements - NetApp Knowledge Base 5: ONTAP 9 - Hardware Universe - The Open Group

To access a LUN on a FAS 8300 system from a VMware ESXi server through the FC protocol, the customer must configure the FC service on the SVM that owns the LUN. The FC service enables the SVM to act as an FC target and communicate with the FC initiators on the host. Without the FC service, the LUN will not be visible to the host, even if the LUN is mapped to an igroup and the FC LIFs are up. The exhibit shows that the FC service is not configured on the SVM, as theoutput of the command vserver fcp initiator show -vserver SVM1 is empty. Therefore, the reason for the problem is that the FC service has not been configured on the SVM. References = Configure an SVM for FC, Create an FC protocol service, Single IQN iSCSI session with ESXi on ONTAP when igroup has two IQNs

 The ONTAP command that will help isolate a possible MTU mismatch is network ping -lif jumbo_01 -vserver svm1_cluster1 -destination 192.168.0.210 -disallow-fragmentation true -packet-size 5000. This command will send a ping packet of 5000 bytes from the logical interface (LIF) jumbo_01 to the destination IP address 192.168.0.210, without allowing fragmentation. If the ping fails, it means that there is an MTU mismatch somewhere along the path. If the ping succeeds, it means that the MTU is consistent and the problem is elsewhere12. References: 1: Check the MTU network setting on the storage system |NetApp Documentation 2: How to adjust the MTU for an ONTAP interface - NetApp Knowledge Base

 The two throughput elements that are controlled by host applications are operation size and concurrency. Operation size refers to the amount of data that is transferred in a single I/O request, and concurrency refers to the number of I/O requests that are issued simultaneously. Both of these factors affect the throughput of a host application, as they determine how much data can be sent or received within a given time period. Larger operation sizes and higher concurrency can increase the throughput, but they may also increase the latency and resource consumption12. References: 1: NetApp Performance Analysis on Data ONTAP - Chapter 3: Host-Side Performance 2: NetApp Performance Analysis on Data ONTAP - Chapter 4: Storage System Performance

Here is my reasoning:

• The system node hardware unified-connect show command displays the status and configuration of the Unified Connect ports on a node1. This command can help you identify if the ports are configured correctly and if they have any errors or faults.
• The ports 0e and 0f on the AFF A300 are 10GbE ports that support both Ethernet and Fibre Channel over Ethernet (FCoE) protocols2. These ports are part of the Unified Connect feature, which enables you to use the same physical port for different protocols without requiring additional hardware3.
• If the ports are offline, it could indicate a problem with the port configuration, the cable connection, the switch configuration, or the protocol settings. The system node hardware unified-connect show command can help you troubleshoot these issues by showing you the port mode, speed, duplex, state, and error count1.
• The other commands in the options are not as helpful for troubleshooting the port issue, because they show different information that is not related to the Unified Connect feature or the port status. For example:

Here are some references that might help you:

1: system node hardware unified-connect show - NetApp 2: AFF A300 system installation - NetApp 3: Unified Connect - NetApp 4: vserver fcp wwpn-alias show - NetApp 5: storage port show - NetApp 6: vserver fcp interface show - NetApp

 FlexGroup requires CIFS shares to use the Continuously Available Feature, which enables transparent failover and recovery of SMB sessions in the event of a node failure or takeover. This feature is only supported by Windows 8 and later clients, and some printers and scanners may not support it either. Therefore, these older Windows XP clients and some printers and scanners are unable to access a FlexGroup over CIFS. References = Supported and unsupported configurations for FlexGroup volumes, NetApp ONTAP FlexGroup volumes — Best practices and implementation guide (page 24)

A B2B type consistency point (CP) occurs when a new CP is triggered before the previous CP is completed, due to the second memory buffer reaching a watermark. This can cause write latency to increase as user write operations are not replied until a write buffer frees up. However, this only affects the aggregate that is undergoing the B2B processing, and not the other aggregates on the same node. Therefore, the performance of the client operations on the data aggregates will not be affected by B2B processing on the root aggregate. References = What is the Back-to-Back (B2B) Consistency Point Scenario?, What are the different Consistency Point types and how are they measured in ONTAP 9?, What are the different Consistency Point types and how are they measured?