I. Installation
Just install the package SAPHanaSR-ScaleOut (and SAPHanaSR-ScalOut-doc).
Please follow the instructions of the Setup-Guide published in our web site at
https://documentation.suse.com/sbp/all/?context=sles-sap and also in the
package SAPHanaSR-ScaleOut-doc.


II. Supported Scenarios and Prerequisites

For the current version of the package SAPHanaSR-ScaleOut, the support is
limited to the following scenarios and parameters:

1. HANA scale-out cluster with system replication.
   Performance optimized, single container (A => B) and
   Performance optimized, multi-tenancy also named MDC (%A => %B).
2. It does NOT support cost optimized scenario.
3. It does NOT support multi-tier or multi-target system replication.
   (a 'third' site, e.g. A => B -> C)
	This restriction will be removed with the next version.
4. It does NOT manage any service IP address for a read-enabled secondary site.
	This restriction will be removed with the next version.
5. The replication mode should be either 'sync' or 'syncmem'.
6. The HANA consists of two sites with same number of nodes each.
7. The two HANA database systems (primary and secondary site) are managed by
   the same single Linux cluster.
8. There are no HANA nodes outside the Linux cluster.
	This restriction will be removed with the multi-target support
	as the 3rd site will not be managed by the cluster.
9. The maximum number of nodes in that single Linux cluster is given by the
   Linux cluster limit.
10. An odd number of nodes is needed to handle split-brain situations
    automatically.
11. A dedicated cluster node might be used as majority maker.
    This dedicated node does not need to have HANA installed and must not run
    any SAP HANA resources for the same SID. Nevertheless resource agents and
    saphostagent needs to be installed and configured, including users.
12. The cluster must include a valid STONITH method.
13. As the STONITH mechanism SBD is recommended. Either disk-based or diskless.
14. Both sites are either in the same network segment (layer 2) to allow an
    easy takeover ofan IP Address, or you need a technique like overlay IP
    addresses in virtual private clouds.
15. Technical users and groups such as <sid>adm are defined locally in the Linux
    system.
16. Name resolution of the cluster nodes and the virtual IP address should be
    done locally on all cluster nodes.
17. Strict time synchronization between the cluster nodes using reliable time
    services like NTP.
18. There is no other SAP HANA system (like QA) on the replicating node which
    needs to be stopped during take-over.
    see 2. No cost optimized scenario is supported.
19. Only one system replication for the SAP HANA database.
    see 3. multi-target not supported
20. Both SAP HANA database systems have the same SAP Identifier (SID) and
    Instance Number.
21. The SAP HANA scale-out system must have only one active master name server
    per site.
22. It must have up to three master name server candidates (SAP HANA nodes with
    a configured role 'master<N>').
	This restriction will be removed with the next version.
23. The SAP HANA scale-out system must have only one failover group.
24. The SAP hostagent must be installed and started on your system.
25. Automated start of SAP HANA database systems during system boot must be
    switched off.
    All SAP HANA instances controlled by the cluster must not be activated
    via sapinit autostart.
26. If the shared storage is implemented with another cluster, that one does
    not interfere with the Linux cluster.
    All three clusters (HANA, storage, Linux) have to be aligned.
27. Automated registration of a failed primary after takeover is possible.
    And for optimal automation, AUTOMATED_REGISTER="true" is recommended.
    But as a good starting configuration for projects, it is recommended to
    switch off the automated registration of a failed primary, therefore the
    AUTOMATED_REGISTER="false" is the default.
    In this case, you need to register a failed primary after a takeover
    manually. Use SAPtools like hanastudio or hdbnsutil.
28. The current resource agent for Scale-Out supports SAP HANA in system
    replication beginning with HANA version 1.0 SPS12 (121) or HANA 2.0 SPS2.
    Older versions do not provide the srHook method srConnectionChanged().

