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Author's profile photo Sivasundaram R

Network Enhancement: Re-routing the SAP HANA Log Shipping Traffic

Introduction:
The primary objective of this article is to setup a dedicated NIC Card for SAP HANA landscapes in which the datacenters across primary and secondary face severe network delays causing Logshipping delays and communication errors. In order to mitigate the above issues recommended SAP solution is to have a dedicated NIC card between Primary datacenter and Secondary datacenter. This document will briefly explain about the scenario, problem encountered, resolution and key steps involved in the setup.

Scenario:
Synchronous replication between Primary and Secondary SAP Hana database (same datacenter) and Asynchronous replication from Secondary to Tertiary SAP Hana database (DR datacenter)

Problem:
Logshipping(Async buffer) throughput from Secondary to Tertiary (network delay) causing performance issue in primary due to rippling effect

Resolution:
Dedicated NIC card was setup between Secondary and Tertiary SAP Hana servers(Primary and Secondary Datacenters) to handle the log shipping traffic efficiently.

Key steps:
1 Create/assign a new IP address for the dedicated NIC cards in Secondary and Tertiary SAP Hana servers in the same subnet.
2 Update the DNS with the new IP address pointing to Secondary and Tertiary SAP HANA servers.
3 The host name should be resolvable with the newly created ips such that if the ip is pinged it should point to the host name accordingly
4 Stop the existing replication between Secondary and Tertiary SAP HANA DB either from HANA studio/HANA Cockpit and un-register the Tertiary SAP HANA DB. Please make sure the replication is disabled.
5 Stop Tertiary SAP Hana DB.
6 Add system replication_hostname_resolution and internal ‘Actual’ host names must be mapped to newly created IP addresses in the global.ini file in Secondary and Tertiary SAP HANA DB.
6 Reconfigure the online changes made to global.ini in the secondary SAP HANA DB by executing command “hdbnsutil –reconfig”.
7 Start the SAP HANA DB in the Tertiary environment. Here in this case we are bringing only the tertiary database down since it would not impact the production load executions in the primary.
8 Re-register the replication and make sure replication is happening fine between Secondary and Tertiary SAP Hana servers.
9 Start the Tertiary SAP HANA DB and check for the replication status.
10 Login to Secondary and Tertiary SAP HANA databases and check in global.ini file and make sure the host name to IP address is mapped correctly.
11 To add the IP address in the routing table to divert the traffic over the datalink (3 Gig)
12 To update the IP address in the application level for the replication to send data from secondary to DR SAP Hana DB
13To Check if the replication is happening via dedicated ip use the command:”hdbcons -e hdbnameserver ‘replication info’ | grep -iE -A 2 ‘(data|log) connection’“

Conclusion:
These are the steps that are required for setting up a dedicated NIC card for routing the replication flow from the network traffic. Fellow SAP readers/bloggers please feel free to post questions related to the above scenario. This case is best recommended for the environments facing lower network bandwidth, higher Logshipping time and replication issues. Please feel free to provide feedback or ask clarifying questions in the comments below this link.

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