High Available ASCS for Windows on File Share – Shared Disk No Longer Required

SAP Highly Available ASCS Now Supports File Share UNC Source

SAP has released documentation and a new Windows Cluster DLL that enables the SAP ASCS to leverage a SMB UNC source as opposed to a Cluster Shared Disk.

The solution has been tested and documented by SAP for usage in non-productive systems and can be used in Azure Cloud. This feature is for SAP NetWeaver components 7.40 and higher.

The Azure Cloud platform fully supports cluster solutions such as Windows Cluster and Suse Cluster in contrast to other Cloud providers.

1. Requirements for SAP Highly Available ASCS on File Share

The requirements for the SAP ASCS on File Share are listed below:

1. SAP Kernel Update: The latest 7.49 [for Netweaver 7.40 or higher] is required.

2. The SAP profile parameter service/check_ha_node=1 must be set

3. The Windows cluster DLL must be updated – 1596496 – How to update SAP Resource Type DLLs for Cluster Resource Monitor

4. The SAP landscape must have a SMB Server to provide the file share \\<SAPGLOBALHOST>\sapmnt

Before deploying this solution review the documentation:

SAP ASCS on File Share Installation Document

2. SMB Server Options for the File Share

There are many options for providing a highly available SMB 3.x compatible share.

These options are documented in this blog here: How to create a high available SAPMNT share?

It is not supported to use the Azure Files Service as Azure Files does not support NTFS ACLs yet.

WARNING: It is not supported to change the share name from \\< SAPGLOBALHOST>\sapmnt to \\< SAPGLOBALHOST>\sapmnt_<SID>

Every SAP SID must have its own unique SAPGLOBALHOST

For example: \\< SAPGLOBALHOST_<SID>>\sapmnt such as

\\sapsmb3_PRD\sapmnt

\\sapsmb3_BWP\sapmnt

\\sapsmb3_SOL\sapmnt

Review this note: 2492395 – Can the share name sapmnt be changed?

Also review:

2287140 – Support of Failover Cluster Continuous Availabilty feature (CA)

2506805 – Transport Directory DIR_TRANS

The SMB server used the SAPMNT share can also be used for Interface Files and the DIR_TRANS

3. Integration with Azure Site Recovery

The SAP ASCS on File Share works in combination with Azure Site Recovery.

Azure Site Recovery is tested and supported with SAP applications.

This blog discusses SAP applications on Azure Site Recovery.

A full whitepaper on protecting SAP applications with Azure Site Recovery

https://docs.microsoft.com/en-us/azure/site-recovery/site-recovery-workload#protect-sap

4. Frequently Asked Questions

Q1. Where to find the Documentation for SAP ASCS on File Share?

A1. SAP ASCS on File Share Installation Document

Q2. Is the SAP ASCS on File Share fully integrated with SWPM (SAPInst)?

A2. The initial installation is via SAPInst and then there are some manual steps required

Q3. What is the recommended SMB server technology?

A3. It is recommended to evaluate all the options. There are pluses and minuses for each option. DFS-R is a technology that is quite mature, supports NFS (for Linux systems) and supports DR scenarios. DFS is site aware – review the documentation about the INSITE option

Q4. Windows 2016 includes a Scale Out File Server (SOFS). Can this be used as the SMB source?

A4. Yes, SOFS is a good option. Note that SOFS is not site aware, this means that if a DR solution is setup with SOFS Servers in remote locations (possibly over slow WAN links) the SMB client [the SAP app server] cannot determine which server is local. This may result in unpredictable performance and is not recommended. If all the SOFS are in the same site SOFS is suitable

Q5. Does the SAP ASCS work with Azure Site Recovery?

A5. Yes, the SAP ASCS on File Share works well with Azure Site Recovery

Q6. Is the SAP ASCS on File Share supported on old kernels?

A6. No, 7.49 [Netweaver 7.40 or higher] is required. Do not run old unsupported kernels

Kernels 7.22 or lower cannot be used with the ASCS File Share as they do not understand the parameter service/check_ha_node=1

Q7. Is the SAP ASCS on File Share supported on Cloud platforms?

A7. The SAP ASCS on File Share works on Azure. Windows cluster solutions do not work correctly on other Cloud platforms that do not support the dynamic assignment, change and start of an IP address.

Q8. Is the SAP ASCS Enqueue Replication Server supported?

A8. Yes, use the SWPM tool to add the ERS onto the cluster.