Understanding the Application Requirements:

The application is very transactional with a 28/72 random, read/write ratio. This indicates a high write intensity, which necessitates optimized storage configurations to handle the I/O load efficiently.

Add Multiple Virtual Disks:

Option B: Add a minimum of four virtual disks to each VM and aggregate them on guest OS level:

By adding multiple virtual disks and aggregating them within the guest OS, the I/O operations can be spread across multiple disks. This can significantly improve I/O performance by leveraging parallelism and reducing I/O contention on a single disk.

This approach also helps in better utilizing the underlying storage infrastructure, which can include multiple SSDs and HDDs managed by Nutanix Distributed Storage Fabric (DSF)​​.

Analysis of Other Options:

Option A: Add one large SSD to each node and enable Flash Mode for the VMs:

Adding a single large SSD may not fully leverage the parallel I/O capabilities needed for high transactional workloads.

Option C: Add a minimum of four SSDs to each node to ensure all writes go to the SSDs:

While this improves performance, it focuses on node-level configuration rather than optimizing VM-level disk I/O distribution.

Option D: Add one large virtual disk to each VM and use it for all application data:

This creates a bottleneck as all I/O operations are directed to a single virtual disk, limiting performance improvements.

Conclusion:

For optimal performance of a highly transactional application with a high write ratio, adding multiple virtual disks and aggregating them within the guest OS is the most effective solution.

References: Nutanix best practices for VM and storage configuration.