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

• 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

 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

 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)

FabricPool is an ONTAP feature that enables tiering of cold data from SSD aggregates to low-cost object storage, either on-premises or in the cloud1. FabricPool requires a license to be installed on the cluster, and the license type depends on the cloud tier being used2. In this scenario, the cloud tier is another ONTAP cluster (FAS8300), which is not supported by the new Cloud Tiering license that is used for most FabricPool configurations3. Therefore, the old FabricPool license that is retained for dark sites or MetroCluster systems using FabricPool Mirror must be used3. The FabricPool license defines the amount of capacity that can be tiered to the cloud tier, and it can be increased by add-on orders4. References:

• 1: FabricPool overview5
• 2: FabricPool requirements6
• 3: Install a FabricPool license2
• 4: ONTAP FabricPool (FP) Licensing Overview1

= 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

• 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

• 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

 The iSCSI service must be enabled on the network interfaces that are used for iSCSI communication. If the iSCSI service is disabled on an interface, the incoming connection requests from the iSCSI initiator will be discarded and the event log will show the message “ISCSI: network interface identifier disabled for use; incoming connection discarded”. To enable the iSCSI service on an interface, you can use the System Manager or the CLI command network interface modify -vserver vserver_name -lif lif_name -data-protocol iscsi. References = Configure the iSCSI protocol with System Manager, [ONTAP 9 Network Management Guide]

 The wafl.dir.size.max event occurs when a directory has reached its maximum directory size (maxdirsize) limit, which prevents new file creation in that directory. The maxdirsize is a volume-level option that can be modified using the volume modify command. To solve this issue, you should increase the maximum directory size for the volume that contains the CIFS share, as long as it does not exceed 3% of the physical memory. Alternatively, you can reorganize the directory structure to avoid having too many files in one directory. References =

• Max Directory size error - NetApp Knowledge Base
• How to identify the target directory of wafl.dir.size.warning - NetApp Knowledge Base
• Post about wafl.dir.size.max | Source.kohlerville.com
• WAFL Max dirsize | uadmin

• The question refers to a scenario where the shelf firmware for an NS224 shelf has not been upgraded on one of the NVMe shelf modules (NSM) after a week of installation.
• The NSM is responsible for managing the communication between the drives and the I/O modules (IOM) in the shelf1.
• The shelf firmware for the NSM is automatically updated when the NSM is inserted into the shelf or when the system is rebooted2.
• If the automatic update does not work, the manual update process involves reseating the NSM, which means removing it from the shelf and inserting it back3.
• Reseating the NSM triggers the firmware update and also resets the NSM’s state3.
• The other options are not correct, because:
• NS224 NVMe drive shelf overview - NetApp
• Shelf firmware update process - NetApp
• Module firmware upgrade stuck on NS224 shelf - NetApp Knowledge Base
• Power cycle a disk shelf - NetApp

 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.

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

• 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]

• The error message indicates that the ONTAP Select Deploy VM cannot connect to the vCenter server due to a network issue1.
• One possible cause of this issue is that the IP address of the ONTAP Select Deploy VM is conflicting with another device on the same network2.
• To correct this problem, you need to change the IP address of the ONTAP Select Deploy VM to a unique and valid address that can reach the vCenter server2.
• You can change the IP address of the ONTAP Select Deploy VM by using the Deploy web interface or the Deploy CLI2.
• After changing the IP address, you need to restart the Deploy services and re-add the vCenter server to the inventory2. References:
• 1: Credential authentication failed with: HostConnectionFailed, NetApp Knowledge Base
• 2: Changing the IP address of the Deploy VM, ONTAP Select 9 Documentation Center

= 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