Ref: https://next.nutanix.com/installation-configuration-23/backplane-network-in-aos-5-5-27291

In a Nutanix cluster, I/O latency can be affected by several factors. Given the scenario where a 32-node hybrid cluster is experiencing I/O latency, one possible cause could be the Information Life Cycle Management (ILM) constantly moving data due to curator scans1.
In a Nutanix cluster, ILM is responsible for managing data placement across different storage tiers. It promotes frequently accessed data to higher-performance tiers (like SSDs) and demotes less frequently accessed data to lower-performance tiers (like HDDs)1. This process involves moving data around, which can cause I/O operations to take longer, leading to increased latency1.
If the working set size (WSS) exceeds the SSD tier capacity, ILM will have to constantly move data between the SSD and HDD tiers to accommodate new data. This constant data movement can lead to increased I/O latency1.
Therefore, if curator scans caused by ILM are constantly moving data, it could be the reason for the observed I
/O latency in this scenario.
References:
* Disk I/O Latency on a Nutanix Cluster | Nutanix Community
* Nutanix Volumes - Recommendations And Best Practices
* Nutanix Support & Insights
* Expand Cluster with Nodes with Higher NIC SPEED (25 GBPS) | Nutanix ...
* [Scaling Up VM Storage Performance on AHV - Volume Group ... - Nutanix]
* [About support for Nutanix segmented iSCSI network | Managing AHV ...]

For a customer with 12 Nutanix blocks distributed across three racks and an additional datacenter 400 kilometers away, achieving the highest level of resiliency involves ensuring both local and remote data protection.
Option B, "Async DR to a remote site," is essential for protecting against site failures by asynchronously replicating data to a branch office. This method is suitable for long-distance replication where latency and bandwidth are concerns.
Option C, "Rack awareness," is crucial in a multi-rack setup to ensure that data is distributed in such a way that a failure of a single rack does not lead to data loss or significant downtime. Rack awareness configures the placement of data replicas across different racks, improving fault tolerance within the primary datacenter.
References:Nutanix documentation on disaster recovery and data resilience strategies, such as those found in the Nutanix Bible and official Nutanix training materials, supports these recommendations, emphasizing the importance of both remote site replication and local redundancy configurations.