We have database on two different server melcoprd and melcodev. Our database is in mcod scenario in which it has 3 tenant database.
MELCODEV
MELCOPRD
We have melcodev hana box in which 3 database instances are installed namely.
HD1-> development database
HQ1-> quality database
HP1-> production database
We have melcoprd hana box in which only one database instance is installed namely.
HP1-> production database
We have installed the hana database with virtual IP/virtual host name for production.
SAP application are also installed with virtual IP/virtual host name in production scenario. Application used to connect to database using the virtual IP .
Instance number of these database are
00 for production
02 for development
04 for quality
We have not used 01 or 03 as instance number because the port used with instance number is used for replication.
ENVIRONMENT
SITE1 = HP1 on melcoprd is site 1 or primary site for preferred data center.
SITE2 = HP1 on melcodev is site 2 or secondary site for second data center.
melcoprdHP1 = HANA system which acts as primary in replication mode
melcodevHP1 = HANA system which acts as secondary in replication mode
Prerequisite for System Replication
1. The hana database on primary and secondary systems are both installed and configured. We have to verified that both are independently up and running.
2. The number of node on primary must be equal to the secondary.
3. The HANA version must be same on both primary and secondary system.
4. The secondary system must have identical SAP system ID and instance number as the primary system.
5. The initial db backup has to be executed before starting the system replication.
System Replication for HP1
Target Solution Overview
All the command are executed with <SID>adm user.
So, here we will discuss 3 scenario.
1. Takeover the database from primary to secondary.
2. Register the primary as secondary site for replication.
3. Take-back to the original primary system.
Before performing a takeover, we will check the replication is working fine.
Verifying the system replication
STEP 1
Verify that system replication is running on melcoprd
enter the following command —–> hdbnsutil -sr_state
this command will show information about the system replication status.
Here we can see our primary site name is melcoprdHP1 and Id is 1.
now we will run python command to check the system replication status
command ——> python systemReplicationStatus.py
Here we can see that data is being replicated from melcoprd to melcodev. Nameserver service contain all the processed data, so it is being replicated.
Now we will verify the replication status on melcodev
enter the following command —–> hdbnsutil -sr_state
this command will show information about the system replication status.
As we can see that the secondary site is melcodevHP1 with Id 2.
now we will run python command to check the system replication status
command ——> python systemReplicationStatus.py
Since replication is happening from melcoprd. We cannot see the replication status since it is not primary site.
1. Takeover the database from melcoprd to melcodev
In our case for takeover we stopped the server.
shutdown melcoprd
command ——> shutdown -h now
SAP application server stop working
takeover the database from melcoprd to melcodev
login to melcodev
command ———-> hdbnsutil -sr_takeover
It will switch the system replication primary site to the secondary site.
It will take over the database from melcoprd to melcodev.
this command will take some time.
SAP application start working.
2. Register the melcoprd as a secondary site for replication
Starts the melcoprd server
Stop the database
command ——-> HDB stop
Now we login the melcodev to check the system replication status.
command ———> python systemReplicationStatus.py
Since no replication is happening as we have not register the melcoprd as secondary database.
So. we will register the melcoprd as secondary site.
Registering the melcoprd as secondary site for replication
command ———–> hdbnsutil -sr_register –name=melcoprdHP1 –remoteHost=melcodev —
remoteInstance=00 –replicationMode=sync –operationMode=delta_datashipping
name—> melcoprdHP1 -> The system to which data will be replicated.
remoteHost—-> melcodev -> The remote host from where the data will be replicated.
remoteInstance —> The instance number of hana database.
replicationMode —-> We can give the mode of replication.
operationMode —-> operation mode may be delta_shipping or logreplay
check the state on melcoprd
command —-> hdbnsutil -sr_state
As we can see primary is melcodev and secondary is melcoprd
Check the replication status from melcodev to melcoprd
login on to melcodev
command ———–> python systemRelicationStatus.py
Start the database on melcoprd
HDB start
3. Take-back to the original primary system
check the status of replication
login to melcoprd
command ———-> hdbnsutil -sr_state
Takeover the database from melcodev to melcoprd
command ———–> hdbnsutil -sr_takeover
login to melcodev and check the system replication status
command ———> python systemReplicationStatus.py
system replication is not active
Making melcodev as secondary system
stop the database
login on melcodev
HDB stop
Registering the melcodev as secondary site for replication
login to melcodev
hdbnsutil -sr_register –name=melcodevHP1 –remoteHost=melcoprd –remoteInstance=00 —
replicationMode=sync –operationMode=delta_datashipping
checking the system replication on melcodev
command ————> hdbnsutil -sr_state
Now we can see that our primary site is melcoprd and secondary site is melcodev
Checking the system replication status on melcoprd
command ——–> hdbnsutil -sr_state
Start the database on melcodev
login on melcodev
HDB start
check the system replication status on melcoprd
login to melcoprd
python systemReplicationStatus.py
We can see replication is working fine.
Source: go.sap.com
No comments:
Post a Comment