Amazon infrastructure, operating system setup and HANA installation
This guide mainly focuses on SAP HANA system replication setup and high availability
cluster configuration steps on Amazon. To set up Amazon infrastructure, which is necessary to
install primary and secondary SAP HANA databases, see the SAP HANA Environment Setup on Amazon Guide
After you have the Amazon infrastructure ready, you will have to perform operating system
configuration and installations of primary and secondary SAP HANA databases as per the
architecture diagram in the previous section. SAP HANA installation steps are detailed in
SAP Installation Guides and Setup Manuals
Hostname resolution
Ensure that both the systems are able to resolve the hostnames of both the cluster
nodes. To fix any DNS issues, add the hostnames of both the cluster nodes to
/etc/hosts
.
# cat /etc/hosts 10.0.0.1 prihana.example.com prihana 10.0.0.2 sechana.example.com sechana
Disable SAP HANA autostart
The high availability cluster will manage the start and stop operations for SAP HANA. Disable the autostart feature after installation is complete.
-
Login as the
sidadm
user on each cluster node and run the following command.# HDB stop # cdpro
-
Edit the SAP HANA profile file named
SID_HDB_instNum_hostname
and set the autostart property to 0. -
Save the profile file and start SAP HANA.
# HDB start # cdpro
Configure SAP HANA System Replication (HSR)
Following are the high-level steps to setup HSR:
-
Enable HANA system replication for the database on the primary cluster node.
-
Register the secondary SAP HANA database node with the primary cluster node and start the secondary SAP HANA database.
-
Verify the state of replication.
The following values are used to configure HSR and high availability cluster in this example:
-
Primary database host name –
prihana
-
Secondary database host name –
sechana
-
Database system identifier (DBSID) –
HDB
-
Instance number –
00
-
Site name of primary node –
PRI
-
Site name of secondary node –
SEC
Enabling system replication in primary node
As <sid>adm
user enables the system replication at the primary
node:
hdbadm@prihana> hdbnsutil -sr_enable --name=PRI
Register the secondary node with the primary node
The SAP HANA database instance on the secondary cluster node must be stopped before registering the database instance for system replication.
After the database instance is stopped, you can register the instance using
hdbnsutil
. On the secondary node, the mode should be either “SYNC“ or “SYNCMEM
In the following example, the replication mode used is SYNC.
As a <sid>adm
user, stop the secondary SAP HANA database,
register the secondary node, and start the SAP HANA database:
hdbadm@sechana> HDB stop hdbadm@sechana> hdbnsutil -sr_register --name=SEC \ --remoteHost=prihana --remoteInstance=00 \ --replicationMode=sync --operationMode=logreplay hdbadm@sechana> HDB start
Verifying the state of system replication
You can use the hdbnsutil
tool to check the system replication mode and
site name:
hdbadm@prihana> hdbnsutil -sr_state checking for active or inactive nameserver ... System Replication State ~~~~~~~~~~~~~~~~~~~~~~~~ mode: primary site id: 1 site name: PRI Host Mappings: ~~~~~~~~~~~~~~ done.
hdbadm@sechana> hdbnsutil -sr_state checking for active or inactive nameserver ... System Replication State ~~~~~~~~~~~~~~~~~~~~~~~~ mode: sync site id: 2 site name: SEC active primary site: 1 ~~~~~~~~~~~~~~
You can view the replication state of the whole SAP HANA landscape using the
following command as a <sid>adm
user on the primary node:
hdbadm@prihana> HDBSettings.sh systemReplicationStatus.py --sapcontrol=1 ... site/2/SITE_NAME=SEC site/2/SOURCE_SITE_ID=1 site/2/REPLICATION_MODE=SYNC site/2/REPLICATION_STATUS=ACTIVE site/1/REPLICATION_MODE=PRIMARY site/1/SITE_NAME=PRI local_site_id=1 ...
Configuring system replication operation mode
When your SAP HANA database is connected as an SAPHanaSR
target, you
can find an entry in the global.ini
which represents the operation mode.
To have your secondary site as a hot standby system, the operation mode configured
must be ‘logreplay
’.
For more details regarding all operation modes, see How To Perform System Replication for SAP HANA
Ensure the operation_mode parameter is set to your desired operation mode in the
global.ini
configuration file on both the primary and secondary nodes.
The path for the global.ini
is
/hana/shared/global/hdb/custom/config/
.
operation_mode = logreplay