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.

• 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 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