You have highly available deployment of SAP NetWeaver on Azure that uses a third-party solution for clustering ABAP SAP Central Services (ASCS)…

Azure shared disks are a feature of Azure Managed Disks that allow a disk to be attached to multiple virtual machines simultaneously. This provides a shared block storage solution suitable for clustered applications like SAP ASCS/SCS. For the goal of cost reduction, Azure shared disks are typically more cost-effective than alternatives like Azure NetApp Files (a premium service) or building and managing a separate cluster for a Scale-Out File Server or NFS share. It simplifies the high-availability architecture by eliminating the need for additional infrastructure for storage replication, thereby lowering the total cost of ownership (TCO).

A. Azure NetApp Files: This is a premium, high-performance file storage service. While it is a valid and supported solution for SAP shared storage, it is generally more expensive than using Azure shared disks, making it a less optimal choice for a cost-reduction initiative.

C. Azure Data Share: This service is designed for securely sharing data with external organizations. It is not a shared storage solution for high-availability clustering and is irrelevant to the technical requirements of an SAP ASCS instance.

D. Storage Spaces Direct: This is a Windows Server feature for building software-defined storage using local disks. It adds complexity and cost by requiring multiple dedicated VMs for the storage cluster, making it less cost-effective than the more direct Azure shared disks solution.

1. Microsoft Learn

High availability for SAP NetWeaver on Azure VMs on SUSE Linux Enterprise Server with Azure shared disk for SAP applications: This document presents Azure shared disks as a solution for SAP ASCS/ERS high availability. It states

"Azure shared disk is a new offering from Azure Managed Disks. It will help you to simplify your SLES high availability cluster." Simplification of architecture directly contributes to cost reduction. (See the "Introduction" section).

2. Microsoft Learn

Azure shared disks: This documentation describes the feature and its intended use cases. It notes

"Shared disks offer shared block storage that can be accessed from multiple VMs... A common use case is for SAP ASCS/SCS...". It positions the feature as a direct solution for this scenario. (See the "Workloads" section).

3. Microsoft Learn

SAP workloads on Azure: planning and deployment checklist: In the storage section

this guide discusses various storage options. While it lists Azure NetApp Files as a high-performance option

Azure shared disks are presented as a native

integrated solution for clustering

which implies a lower TCO compared to more complex or premium services. (See the "Decide on a storage type" section).