S/4HANA failover between DataCenters without HANA Replication

[Farid]

Hello,

We are trying to figure out a way to ensure that our S/4HANA Systems ( installed on two servers DB HAHANA machine and S/4HANA machine) could be failover between our two datacenters, this without using HANA System Replication, because we do not really need it.

Yes, It sound a bit weird, I hope this graphic would make it a bit easier to understand :

Our Infrastructure consists of two datacenters (separated by no more than 50 km)

Each datacenter provides several partitions, AIX,IBMi,Linux, …

The storage of all those partitions is actually replicated between the two datacenters.

The replication performed at the storage level, is established by IBM San Volume Controller (SVC, in synchronous mode)

AIX and IBMi have their own cluster and high Availability tools, ensuring that AIX and IBMi and the softwares running on them, are failed over the second datacenter every Sunday

The failover is performed manually by Operators by running scripts and following simples and shorts procedures

This allows us to perform maintenance operations on their Datacenter 1 (OS Upgrade, etc …), while their AIX and IBMi applications are running on Datacenter 2.

The following week we failover the applications to Datacenter1, and perform their maintenance on Datacenter2

As for the storage, a SanVolumeController feature ensures that whenever the applications have been failed over to Datacenter2, Storage 2 is used, and vice-versa.

Now, we would like to establish the same failover procedure for the Linux (SLES for SAP SP2 IBM Power ppc64-le) partition

A SAP S/4HANA1610 Landscape has been recently deployed on the Datacenter 1 , which consists of :

• A Linux Server hosting the HANA 2.0 Database, with its associated virtual IP address, and the associated Linux filesystems containing OS data or Application data (HANA Data,logs ,etc ..)
• A Linux Server hosting the S/4HANA Application server, with its associated virtual IP address, and the associated Linux filesystems containing OS data or Application data (SAP and business Data,logs ,etc ..)

As you can imagine, we do not need the SAP HANA Replication feature, as the synchronous replication of the whole Linux partition is already done at a much lower level by IBM SVC.

What we would like to do do is implement is a procedure/tool/software that would allow us to switch the Linux ressources between the datacenters in the correct sequence, that procedure would be triggered manually once a week by the operators.

So let us say we are switching the Linux applications from Datacenter 1 to Datacenter 2 , the procedure would perform the following tasks in the following sequence :

• The applications on both servers HANA and SAP S/4HANA will be properly stopped on Datacenter1
• The virtual IP adress of the HANA server will be switched to Datacenter2
• The Linux filesystems of the HANA server will be unmounted from Datacenter1 , and remounted on Datacenter 2 (Some fencing mechanism should ensure that Filesystems are no longer mounted on Datacenter 1)
• The virtual IP adress of the S/HANA server will be switched to Datacenter2
• The Linux filesystems of the S/HANA server will be unmounted from Datacenter1 , and remounted on Datacenter 2 (Some fencing mechanism should ensure that Filesystems are no longer mounted on Datacenter 1)
• The applications HANA and then SAP/4HANA will eventually be restarted

And there is one additional constraint, as mentioned, the point of the whole manual weekly switchover is to be able to perform système maintenance on one datacenter while the applications (HANA and S/4HANA) are running on the other datacenter. That would mean that, in case SAP applications are running on Datacenter 2, the system engineers should still be able to restart Linux (And Linux OS Only filesystems/mountpoints on Datacenter 1 to upgrade Suse Linux For example.

So here is my question :

I understand that we could try to write a Linux script that would perform the failover of the aforementioned tasks in the correct sequence, but we were wondering if there wasn't already a tool or cluster feature allowing us to do that in a more secure manner ?

Most of the Suse/SAP litterature on the subject deals with the Suse Cluster For HANA System Replication but that is not relevant in our case. Is there any other cluster feature that would allow us to monitor and failover SAP ressources.

Thank you very much for your attention