NS0-593 NetApp Certified Support Engineer ONTAP Specialist Questions and Answers

Data. However, I cannot guarantee the accuracy or completeness of this answer, and you should verify it with the NetApp Support Engineer ONTAP Specialist documents and learning resources.

Here are some references that might help you:

1: qos statistics volume latency show - NetApp 2: How to use and understand qos statistics commands to monitor volume latency in real time - NetApp Knowledge Base

= The -transport parameter specifies the protocol used to send AutoSupport messages, which should be HTTPS by default. The -proxy-url parameter specifies the proxy server used to sendAutoSupport messages, which should be the Connector’s IP address and port if the Cloud Volumes ONTAP nodes do not have outbound internet access. These two parameters can be used to check the AutoSupport configuration and connectivity status. References = Verify AutoSupport setup, Troubleshoot your AutoSupport configuration, High-availability pairs in Azure

• IQN stands for iSCSI Qualified Name, which is a unique identifier for an iSCSI initiator or target1.
• ONTAP uses IQN to authenticate and authorize iSCSI sessions2.
• If two hosts have the same IQN, they will cause a conflict and ONTAP will reject the new session request from the second host3.
• This will result in the host losing the connection to the iSCSI target and then reporting that the session was reestablished, as shown in the exhibit.
• To avoid this problem, each host should have a unique IQN. References:
• iSCSI Qualified Name (IQN) - NetApp
• iSCSI authentication and authorization - NetApp
• Troubleshooting iSCSI issues - NetApp
• [Configuring iSCSI initiators - NetApp]

• SnapMirror is a data replication technology that allows efficient and flexible data protection and disaster recovery for NetApp ONTAP storage systems1
• SnapMirror transfers data between source and destination volumes using a network connection. SnapMirror can use storage efficiency features such as compression and deduplication to reduce the amount of data transferred and stored1
• SnapMirror transfers are scheduled and controlled by policies that define the frequency, retention, and priority of the transfers. SnapMirror policies can also specify the network bandwidth limit for the transfers2
• SnapMirror transfers are considered background tasks that run in the absence of user workload. SnapMirror transfers can consume CPU and disk resources on both source and destination systems, depending on the amount and type of data being replicated3
• SnapMirror transfers can throttle up or down depending on the availability of system resources and network bandwidth. SnapMirror transfers will throttle up when there is nouser workload, and throttle down when there is user workload. This is to ensure that SnapMirror transfers do not impact the performance of user operations3
• Therefore, if a customer is concerned with high CPU and disk utilization on their SnapMirror destination system, the best answer is to explain that background tasks such as SnapMirror throttle up in the absence of user workload. This is normal and expected behavior, and it does not indicate a problem with the system3

References:

1: ONTAP 9 Data Protection - SnapMirror - The Open Group 2: ONTAP 9 Data Protection - SnapMirror Policies - The Open Group 3: SnapMirror storage efficiency configurations and behavior - Resolution Guide - NetApp Knowledge Base

• 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

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?

 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

 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

 To assign storage access to an NVMe protocol host, you need to configure the following objects:

• The NVMe subsystem, which is a logical entity that represents a group of NVMe namespaces that can be accessed by one or more hosts1.
• An NVMe LIF, which is a logical interface that provides network connectivity for the NVMe subsystem2.
• The NVMe namespace, which is a logical volume that is exposed to the host as an NVMe device1.

You do not need to configure the NVMe broadcast domain or the NVMe LUN, as these are not relevant for NVMe protocol host access. References = 1: Configuring NVMe-oF - Hitachi Vantara Knowledge 2: Basic VMware NVMe Architecture and Components

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

 Quiescing the SnapMirror relationships before upgrading the ONTAP software ensures that the data replication is completed and consistent across the source and destination volumes. This prevents any data loss or corruption due to the upgrade process. Quiescing also suspends the scheduled updates until the relationships are resumed, avoiding any delays or failures in the transfers. The other options are not effective in preventing the SnapMirror problems after the upgrade. References =https://docs.netapp.com/us-en/ontap/upgrade/concept_upgrade_requirements_for_snapmirror.html

https://docs.netapp.com/us-en/ontap-systems-upgrade/upgrade-arl-auto-app/resume_snapmirror_operations.html

• 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

= 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

 To enable DDNS updates to work, two actions should be performed:

• Remove the NFS protocol from the cifs_01 data LIF. This is because DDNS updates are only supported for LIFs that have only one data protocol enabled1. The cifs_01 LIF has both NFS and CIFS protocols enabled, which prevents it from registering its DNS record dynamically. By removing the NFS protocol from the cifs_01 LIF, it will become eligible for DDNS updates.
• Enable the -is-enabled parameter for the SVM DDNS services. This is because the -is-enabled parameter controls whether the SVM sends DDNS updates to the DNS servers2. The exhibit shows that the -is-enabled parameter is set to false for the svm1 SVM, which means that it does not send any DDNS updates. By enabling the -is-enabled parameter, the SVM will start sending DDNS updates for its eligible LIFs. References:
• 1: Configure dynamic DNS services3
• 2: Manage DNS/DDNS services with System Manager4

• A speed mismatch occurs when the cluster ports on different nodes have different speeds, such as 10 Gbps and 40 Gbps1.
• A speed mismatch can cause packet loss, retransmits, and latency on the cluster network, especially when data is accessed indirectly, meaning that the node serving the data is different from the node hosting the LIF2.
• In this scenario, the AFF A300 nodes have 10 Gbps cluster ports, while the AFF A700 nodes have 40 Gbps cluster ports, creating a speed mismatch on the cluster interconnect34.
• The Cisco Nexus 3132Q cluster interconnect switches support both 10 Gbps and 40 Gbps cluster ports, but they have a shallow buffer size of 9 MB per port, which can be easily overwhelmed by the bursty traffic generated by the speed mismatch.
• To solve this problem, you need to either upgrade the cluster ports on the AFF A300 nodes to 40 Gbps, or downgrade the cluster ports on the AFF A700 nodes to 10 Gbps, to achieve a homogeneous cluster interconnect1.
• Alternatively, you can use QoS policies to limit the bandwidth of the cluster ports to avoid oversubscription and congestion on the cluster interconnect. References:
• 1: Cluster network cabling, ONTAP 9 Documentation Center
• 2: Cluster Network Latency - Troubleshooting Guide, NetApp Knowledge Base
• 3: AFF A300 Tech Specs, NetApp
• 4: AFF A700 Tech Specs, NetApp
• [5]: Why do network speed mismatches create problems with shallow buffered switches?, NetApp Knowledge Base
• [6]: How to use QoS to limit the bandwidth of cluster ports, NetApp Knowledge Base