Home > Lab 05. Change to Cost Optimized Scenario > Task 01. Change HANA HSR Config

Task 01. Change HANA HSR Config

Changing the HSR option for QAS system on standby system. We are going to change Global Memory setting.

Connect to sechana through Session Manager.
- After log in AWS Management Console, connect to EC2 Instance Console
- Select HANA-HDB-Secondary instance, click Action, and click Connect.
- Select Session Manager and click Connect.
After connecting as root user, change cluster to maintenance mode and change HSR and Global Memory settings.
- Change cluster to maintenance mode.
```
sudo su - root
crm node maintenance prihana
crm node maintenance sechana
```
- Check crm maintenance status
```
crm_mon -rfn1
```
After connecting as hdbadm user, stop HDB, reduce memory resource usage of the secondary SAP HANA DB (sechana), and set preload option to false.
- (sechana) HDB STOP
```
su - hdbadm
HDB stop
```
- (sechana) Change global.ini settings. Open global.ini with VI editor. And add the options below.
```
vi /usr/sap/HDB/SYS/global/hdb/custom/config/global.ini

[system_replication]
...
preload_column_tables = false #Add-on

[memorymanager]
global_allocation_limit = 24576
```

After Takover, change SAPHanaSR-Hook so that the existing settings can be restored.

(sechana) After log in root user, Back up the script before modifying SAPHanaSR.py.

exit
cd /usr/share/SAPHanaSR/
cp -pr SAPHanaSR.py SAPHanaSR.py.default

(sechana) Modify the SAPHanaSR.py script as follows:

Block 1(AS-Is)
Block 1(To-Be)
Block 2(AS-Is)
Block 2(To-Be)
Please modify the script as below.

vi SAPHanaSR.py

# Block 1
from hdb_ha_dr.client import HADRBase, Helper
import os, time
from hdbcli import dbapi

dbuser = "SYSTEM"
dbpwd = "Init12345!"
dbport = 30013
stmnt1 = "ALTER SYSTEM ALTER CONFIGURATION ('global.ini','SYSTEM') UNSET ('memorymanager','global_allocation_limit') WITH RECONFIGURE"
stmnt2 = "ALTER SYSTEM ALTER CONFIGURATION ('global.ini','SYSTEM') UNSET ('system_replication','preload_column_tables') WITH RECONFIGURE"

# Block 2
def postTakeover(self, rc, **kwargs):
"""Post takeover hook."""
self.tracer.info("%s.postTakeover method called with rc=%s" % (self.__class__.__name__, rc))
if rc == 0:
  # normal takeover succeeded
  conn = dbapi.connect('localhost', dbport, dbuser, dbpwd)
  cursor = conn.cursor()
  cursor.execute(stmnt1)
  cursor.execute(stmnt2)
  return 0
elif rc == 1:
  # waiting for force takeover
  conn = dbapi.connect('localhost', dbport, dbuser, dbpwd)
  cursor = conn.cursor()
  cursor.execute(stmnt1)
  cursor.execute(stmnt2)
  return 0
elif rc == 2:
  # error, something went wrong
  return 0

After connecting as hdbadm user, start HDB, and perform TAKEOVER TEST.
- (sechana) HDB START
```
su - hdbadm
HDB start
```
- (sechana) Check HSR status.
```
hdbnsutil -sr_state
```
- (sechana) takeover to sechana
```
hdbnsutil -sr_takeover
```
- (sechana) After Takeover, check whether global.ini setting is restored by SAPHanaSR.py.
```
cat /usr/sap/HDB/SYS/global/hdb/custom/config/global.ini
```
- Since HA Cluster is currently in maintenance mode, automatic Takeover or Takeback using HA Cluster is not possible. To restore HSR to its original state, manually reset the HSR in the following order.
- Keep the connection of sechana, and also connect to prihana through Session Manager.
  - Connect to EC2 Instance Console.
  - Select HANA-HDB-Primary instance, click Action, and click Connect.
  - Select Session Manager and click Connect.
- (prihana) After connecting as hdbadm user, execute sr_register as seconadry Database
```
sudo su - hdbadm
HDB stop

hdbnsutil -sr_register --remoteHost=sechana --remoteInstance=00 --replicationMode=sync --name=HAP --operationMode=logreplay
HDB start
```
- (prihana) Check the synchronization status
```
hdbnsutil -sr_state
```
- (prihana) takeback to prihana
```
hdbnsutil -sr_takeover
```
- (sechana) After connecting as hdbadm user, execute sr_register as seconadry Database
```
su - hdbadm
HDB stop

hdbnsutil -sr_register --remoteHost=prihana --remoteInstance=00 --replicationMode=sync --name=HAS --operationMode=logreplay
```
- (sechana) Change global.ini settings. Open global.ini with VI editor. And add the options below.
```
vi /usr/sap/HDB/SYS/global/hdb/custom/config/global.ini

[system_replication]
...
preload_column_tables = false #Add-on

[memorymanager]
global_allocation_limit = 24576
```
- (sechana) After connecting as hdbadm user, HDB start
```
HDB start
```