NS0-593 Sample Questions Answers

• The question describes a scenario where the controller and client have a significant difference in their reported latency for the same datastores.
• The controller’s latency is 1 ms, which is within the normal range for ONTAP-based datastores1.
• The client’s latency is 15 ms, which is much higher than the controller’s latency and could indicate a performance issue on the client side2.
• Therefore, the next step is to investigate the client that reports high latency and identify the possible causes, such as network congestion, misconfiguration, resource contention, or application issues23.
• The other options are not relevant or appropriate for this scenario, because:
• ONTAP 9 Performance - Resolution Guide - NetApp Knowledge Base
• Performance troubleshooting - NetApp
• How to troubleshoot performance issues in Data ONTAP 8 7-mode
• Cluster interconnect network - NetApp
• How to generate a sync core on a node - NetApp 

The error message indicates that the specified path “/vol1” does not exist in the namespace belonging to Vserver “svm1”. This means that the volume “vol1” has not been mounted to the Vserver’s namespace, which is required for creating a share. The volume type, the CIFS service status, and the CIFS service mode are not relevant to the error. 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

= According to the NetApp Knowledge Base1, while Cloud Volumes ONTAP supports FlexGroup volumes, Cloud Manager does not. If you create a FlexGroup volume from System Manager or from the CLI, then you should set Cloud Manager’s Capacity Management mode to Manual. Automatic mode might not work properly with FlexGroup volumes. The other options are incorrect because Cloud Volumes ONTAP does support FlexGroup volumes2, the CapacityManagement Mode should not be set to Automatic, and Cloud Manager is not required to provision the FlexGroup volume3. References = 1, 2, 3

= 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

 Updating the Vscan servers one at a time can prevent the clients from losing access to the files on the CIFS SVM, as there will always be at least one Vscan server available for scanning. Disabling the -scan-mandatory flag in the Vscan policy can also avoid the issue, as it allows the clients to access the files even if there are no Vscan servers online, but this may compromise the security of the data. Enabling the -scan-mandatory flag or modifying the CIFS shares to be CA shares will not help, as they do not affect the availability of the Vscan servers or the scanning process. References = Vscan server installation and configuration, Update the Vscan On-Access policy configuration for an SVM

• 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

 = The correct action to bring the cluster online and allow Node02 to serve data is to perform a takeover with the storage failover takeover -ofnode Node01 -option force command. This command will force Node02 to take over the resources of Node01 and serve the data from both nodes. This is necessary because Node01 is not responding and cannot initiate a graceful takeover. The other options are not correct because they will either destroy the existing cluster configuration (A and D) or reboot the node without taking over the resources of the other node(B). References = 1 Halt or reboot a node without initiating takeover in a two-node cluster - NetApp Documentation 2 Solved: Graceful shut down - NetApp Community

= The cause of the customer’s problem is that the port has an incorrect SFP inserted. According to the AutoSupport data, the node 1 has a device type of XL710 BQ, which is a 40GbE adapter that requires a QSFP+ transceiver1. However, the part number of the adapter is 111-02590, which is a 10GbE adapter that requires a SFP+ transceiver2. This mismatch prevents the link from coming up on node 1. The customer should replace the adapter with the correct one or use a compatible transceiver for the existing adapter. References = 1: NetApp Hardware Universe - X1144A 2: NetApp Hardware Universe - X1147A

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

= 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 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

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.

• A type B consistency point (CP) is triggered when the NVRAM buffer is full and needs to be flushed to disk. A type B CP indicates that the write workload is higher than the disk throughput, and the system is experiencing back pressure1
• A switchless cluster is a cluster configuration that does not use external switches for cluster interconnect and management network. A switchless cluster has lower bandwidth and redundancy than a switched cluster, and is limited to two nodes2
• The exhibit shows the output of the sysstat -x command, which displays the system performance statistics in extended mode. The output shows that the system has high CPU utilization, high disk utilization, high NVRAM utilization, and several type B CPs. These are signs of performance issues and resource contention3
• The best corrective action to address these consistency points is to add an additional shelf of twenty-four 1.8 TB disks. This will increase the disk capacity and throughput, and reduce the disk utilization and the frequency of type B CPs4
• Creating additional data LIFs will not address the consistency points, because the data LIFs are used for data access protocols, not for NVRAM flushing5
• Converting the 2-node switchless cluster to a 2-node switched cluster will not address the consistency points, because the cluster interconnect and management network are not related to the disk performance6
• Replacing the twenty-four 1.8 TB disks with twelve 4 TB disks will not address the consistency points, because the disk throughput will not increase, and the disk utilization will remain high7

References:

1: Where can I learn more about Consistency Points? - NetApp Knowledge Base 2: ONTAP 9 - Cluster and SVM Peering Express Guide - The Open Group 3: ONTAP 9 - Commands: Manual Page Reference - The Open Group 4: ONTAP 9 - Hardware Universe - The Open Group 5: ONTAP 9 - Network Management Guide - The Open Group 6: ONTAP 9 - Clustered Data ONTAP Concepts Guide - The Open Group 7: ONTAP 9 - Logical Storage Management Guide - The Open Group

 According to the NetApp Knowledge Base, adding a second NS224 shelf to an existing stack can cause the first shelf ID to change to the serial number if the cables are not connected properly1. This can also result in a Medium Impact error message: Shelves with both connections via the same SAS path detected2. This situation is not normal for a NetApp AFF A800 system andcan affect performance and availability. The cables should be reconnected according to the SAS cabling rules and concepts for shelves with IOM12/IOM12B modules3 and the controller-to-stack cabling worksheet template for quad-pathed connectivity4. References = Shelves with both connections via the same SAS path detected, Adding a second NS224 shelf, changes first shelf ID to the serial number, SAS cabling rules and concepts - shelves with IOM12/IOM12B modules, Controller-to-stack cabling worksheet template for quad-pathed connectivity.