SAP HANA additional information

Setting log mode overwrite 

During successful VDB creation, the log mode is set to overwrite, even if a different mode was used for the source. It means that "No log backups" are created. When SAP HANA savepoints are written, log segments are immediately freed to be overwritten by new log entries

SAP HANA port control 

Starting with Delphix Engine 6.0.10.0 and SAP HANA 6.1.0, Delphix introduced a solution that keeps the port numbers consistent throughout the VDB life cycle so that the connections made to the VDBs are not disrupted during their life cycle.

User specified ports

Prior to version 6.1.0 of the connector, port numbers were handled differently and could vary across dataset snapshots. Therefore, every VDB had its own ports and connections for internal and external communication. When operations such as rewind, refresh, or enable are performed on VDBs, this caused port instability because the port numbers could change even when the VDB name remains the same. The below points further elaborate on this limitation. 

1. The plugin uses SAP HANA-provided port numbers which are selected from the available pool of port numbers in the bottom-up approach that means an idle port number at the bottom will be picked first for use. 

2. The plugin does not have any mechanism to remember these port numbers and use them from the pool at the time of creating any tenant database again at the time of enabling, refresh, or rewind. 
   So if we had a tenant TEST having a service indexserver at 30043 port number, then after the refresh, rewind or enable, there will be a chance that 

   1. The same port number (30043) is not available 

   2. Any port number less than the one being used earlier (30043) is now available. 

So, there are chances that the tenant TEST is provided with another port number for the same service by SAP HANA and if there was any connection made to the tenant TEST at 30043 will now be disrupted. Hence there is a need for a solution that allows the database to keep the port number consistent throughout the VDB life cycle.

To solve the above a new method was introduced with connector version 6.1.0 to provide port number control and consistency by the solution.

How does the SAP HANA port allocation work? 

The port control feature now provides an option to specify port numbers at the time of VDB creation. This can be done in the following two ways. 

User-specified SAP HANA ports 

See the procedure for Provisioning SAP HANA VDBs where the user can specify the SAP HANA service and port number at the time of VDB creation. 

By Plugin itself 

If the service and port numbers are not provided by the user on the user interface, then the connector itself will decide the port number and will keep the ports consistent throughout the life of a VDB. 

 This is how the plugin chooses the ports: 

• It is based on the value of the reserved_instance_number parameter in the global.ini file. This file is located at /hana/shared/{DATABASE_SID}/global/hdb/custom/config. If this parameter is not defined in global.ini, then the value of the instance number will be used.  

• Ports will be decided by the SAP HANA plugin in a top-down manner which means that the topmost port which is free will be used first and so on.