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= The “Urge” column in the flexgroup show command indicates the urgency of data rebalancing for each constituent volume. A non-zero value means that the data placement is uneven across the volumes, which can affect the performance of the FlexGroup. The target value is the desired percentage of data for each volume, and the difference value is the deviation from the target. The FlexGroup tries to balance the data placement by moving data between the volumes, but this process can be slow or interrupted by other factors. Therefore, it is recommended to monitor the “Urge” column and take corrective actions if the values are high orpersistent. References = What do “flexgroup show” target and urgency and other columns mean?, NetApp ONTAP FlexGroup volumes — Best practices and implementation guide

 = The multiprotocol volume allows clients to access files using both NFS and SMB protocols. The NFS protocol is case-sensitive, meaning that Test.txt and TEST~1.TXT are two different files. The SMB protocol is case-insensitive, meaning that it treats uppercase and lowercase letters as the same when searching for a file. Therefore, when the user opened the file from a Windows system using SMB, the system could not distinguish between Test.txt and TEST~1.TXT and displayed one of them arbitrarily. This could lead to confusion and data loss if the user modified or deleted the wrong file. References = Client protocols; Multiprotocol NAS in NetApp ONTAP Overview and Best Practices, page 30-31.

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

= CPU utilization in ONTAP is not a linear measure of the system load, nor can it be used alone as a measure of the overall system utilization. ONTAP uses a Coarse Symmetric Multiprocessing (CSMP) design which partitions system functions into logical processing domains, each with its own scheduling rules and resource availability. Therefore, a high CPU utilization does not necessarily indicate a performance problem, unless it is accompanied by other contributing factors such as high latency, low throughput, or high queue depth. ONTAP has several mechanisms to optimize CPU usage and balance the workload across the cores, such as WAFL parallelization, exempt processing, and CPU pinning. The CPU utilization reported by the sysstat command is an average across all cores and domains, and does not reflect the actual CPU activity or availability for each domain. Therefore, the CPU is not a first-order monitoring metric for ONTAP, and other metrics such as latency, throughput, and queue depth should be considered first. References = What is CPU utilization in Data ONTAP: Scheduling and Monitoring?, How to measure CPU utilization, What are CPU as a compute resource and the CPU domains in ONTAP 9?, Monitoring CPU utilization before ONTAP upgrade

= 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

= ONTAP Select supports REST and Ansible as automation methods. REST is the primary foundation for the automation technologies, and Ansible is a popular tool for automating ONTAP Select deployments using roles and playbooks. References = ONTAP Automation documentation, Automate ONTAP Select deployments with Ansible

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 error message indicates that the volume my_data_vol is WAFL inconsistent, which means that there is a discrepancy between the data blocks and the metadata in the file system. This can be caused by various factors, such as hardware failures, software bugs, power outages, or network disruptions. The first action to correct this issue is to determine the root cause behind the inconsistency before attempting any recovery procedure, as recommended by the NetApp documentation1. This is because some recovery procedures, such as wafliron or storage takeover, may not work or may cause further damage if the underlying cause is not resolved. For example, if the inconsistency is due to a faulty disk or shelf, running wafliron may not fix the problem and may even corrupt more data. Therefore, it is important to identify and isolate the cause of the inconsistency before taking any further steps. References = 1 Volume Showing WAFL Inconsistent - NetApp Knowledge Base

The VMware feature that is supported by ONTAP software to identify and follow I/Os from each VM on the shared FC LUN-backed datastores is Virtual machine ID (VMID). VMID is a unique identifier assigned to each VM by the vCenter Server. ONTAP software can use VMID to map the VMs to the FC LUNs and provide visibility into the I/O performance and latency of each VM. This feature is also known as Virtual Storage Console (VSC) for VMware vSphere12. References: 1:Virtual Storage Console for VMware vSphere | NetApp Documentation 2: How to use Virtual Storage Console (VSC) to monitor the performance of virtual machines - 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