This article is contributed. See the original author and article here.
Background: SAP requirement of Highly Available share.
There are several possible solutions to achieve highly available SAPMNT for SAP Instance as listed here. On Azure, SOFS is one of the solutions for consideration, being the Microsoft technology and it works well with SAP Global share. I have not come across a recommendation from SAP for General purpose file share on the cloud, but there is a recommendation from Microsoft Azure when using SOFS share for SAPMNT & general purpose share. The consideration is mainly around the potential performance impact and feature supportability.
In general, there are two types of shares required on SAP Solution.
- SAP Global share: Starting SAP Kernel 749, SAP has updated the Central service architect to be a more cloud-friendly [ share-nothing model] architect. SAP central services ( message and enqueue processes) are separate from the SAP global host files. SAP Global share hosts the physical location of SAP kernel binaries and is critical for SAP System availability.
- General Purpose File share: The general file share is used by the SAP systems based on the business requirement and related application usage. It can be an interface directory used by the SAP systems to transfer data between SAP/Non-SAP systems or images/HTTP files used by the SAP portal system or different file formats used by the applications within the solution including non-SAP. It is not a SPOF for SAP system availability but can be critical for SAP business processes based on the application usage. We need to understand the usage of the share in our environment, but in general, these type of shares host multiple smaller files with higher change rate and that result in potential performance overhead because of the large number of changes when used with CA feature enabled.
SOFS & General Purpose share on Azure for SAP:
1. Scale-Out File Share: Active-Active mode, ReFs File system with CSV & CA feature enabled.
- There are the prerequisites to using SOFS for SAP Global share, attached here.
- CA feature must be enabled to ensure a transparent failover functionality is activated, it avoids batch failure due to the (A)SCS failover, SAP Note 1911507
- Multi-SOFS configuration with independent CSV’s for SAP Systems safeguards against single share corruption scenario.
- DFS Namespace can be used for simplicity of //<Logical>/sapmnt/<SID>, it helps with Production and DR use case.
2. General/Generic purpose File Share: Active-Passive mode, CA feature adds overhead resulting in a potential performance issue.
- SOFS is not recommended with workload with a high rate of file operations on the share, official doc here
- With the CA feature, the application will lose around 40% I/O performance. SAP Note 2287140
- A use case of General File share is active-passive to host general files with multiple formats for SAP/Non-SAP Application.
- Blog shares further detail with regards to the SOFS usage.
Considerations for high load scenarios:
- S2D-SOFS [ReFs_csv] recommended for hosting sapmnt share with CA feature to activate application transparent failover.
- S2D-FS [ReFs] recommended for general purpose share [ Archive, Interface, Trans, Trex, BOBJ].
Microsoft invests heavily in R&D to bring new features to support SAP On Azure customers, there are options for customers looking for alternatives to S2D technology on Azure.
@hdamecharla thank you for providing a summarized view of the highly available SAPMNT options available in Azure
Refer blog for Azure Files – NFS use-case.
For Azure Shared Disk -SMB use-case.
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