Netapp NS0-593 Practice Test Questions Answers

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.

 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.

= 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

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

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