Hi again,
My name is Man-Ted Chan and I’m from the SAP HANA product support team. Recently I’ve been seeing a few issues in regards to High Availability (HA) environment using system replication so I’m writing this piece on setting up the HA along with some troubleshooting tips, and SAP notes.
To avoid confusion with the terminology I will refer to another posting on the SCN:
http://scn.sap.com/docs/DOC-52345
Also I've had to break up this blog into two parts as I hit a limit on the number of images that can be in a single blog posting.
These are steps from, but done in an SP09 environment:
http://scn.sap.com/docs/DOC-47702
I have included screen caps, tests, and log snippets
Setting up primary
When setting up the system replication a backup needs to exists, as a test I will show what happens when there is no backup:
Right click on your primary system and select ‘Configure System Replication…’
As we can see we cannot proceed with the replication as there is no backup. In the next few images we will create the backup.
Afterwards try and create the replication again. Please note that field ‘Primary System Logical Name’ can be whatever you want, but I chose the name ‘primary’.
After this is ran the following can be found in the nameserver trace
==== Starting hdbnsutil, version 1.00.090.00.1416514886 (fa/newdb100_rel),
i Basis TraceStream.cpp(00469) : MaxOpenFiles: 1048576
i Basis TraceStream.cpp(00472) : Server Mode: L2 Delta
i Basis ProcessorInfo.cpp(00713) : Using GDT segment limit to determine current CPU ID
i Basis Timer.cpp(00650) : Using RDTSC for HR timer
i Memory AllocatorImpl.cpp(01326) : Allocators activated
i Memory AllocatorImpl.cpp(01342) : Using big block segment size 8388608
i Basis TopologyUtil.cpp(03894) : command: hdbnsutil -sr_enable --name=primary --sapcontrol=1
w Environment Environment.cpp(00295) : Changing environment set SSL_WITH_OPENSSL=0
i sr_nameserver TopologyUtil.cpp(02581) : successfully enabled system as system replication source site
If you wanted to use the command line to create this replication run the following:
hdbnsutil -sr_enable --name=< Primary System Logical Name>
After this your system is now enabled for system replication
You will have to stop the HANA servers on the secondary server prior to setting up the replication. Right click on the server and select ‘Configuration and Monitoring’->’Configure System Replication…’ again, please note that the SID is the same.
At this step you will name the replication in the ‘Secondary System Logical Name’ and enter the host from the above (note that the Instance number is non-editable)
Replication mode options that are available are the following:
The above is from the SAP HANA Admin guide:
http://help.sap.com/saphelp_hanaplatform/helpdata/en/54/01f498b2c84fb5b3bcdcbda948d991/content.htm?f...
This can be done via the command line
hdbnsutil -sr_register --remoteHost=<primary hostname> --remoteInstance= --mode=<sync/syncmem/async> - -name=< Secondary System Logical Name>
During this registration I ran into the following error
I then ran it via the command line to show the error
I checked the listed nameserver trace to see if there is any other information
==== Starting hdbnsutil, version 1.00.090.00.1416514886 (fa/newdb100_rel),
e Configuration ConfigStoreManager.cpp(00693) : Configuration directory does not exist.
e Configuration
e sr_nameserver TNSClient.cpp(06778) : remoteHost does not match with any host of the source site. all hosts of source and target site must be able to resolve all hostnames of both sites correctly
…
From this error we can see that the landscape between the two do not match. I checked the landscape in the primary and secondary
Here we can see that in secondary server there is the ‘sapstartsrv’ process. After this is resolved re-run the wizard or enter in the hdbnsutil command
‘Initial full data shipping’ is the equivalent to running hdbnsutil –sr_register –force_full_replica
If parameter is set, a full data shipping is initiated. Otherwise a delta data shipping is attempted.
If you run this via command line you will have to manually start up the secondary server
For more information on the hdbnsutiloptions please refer to the following reference guide
You can check the status of the replication in studio and via command line. The below screen caps
Check the name server trace to see following success messages upon startup to see the replication:
TREXNameServer.cpp(12634) : called registerDatacenter from registrator=xxxx301545c
i sr_nameserver TREXNameServer.cpp(12776) : registerDatacenter; new disaster recovery site id =2
i sr_nameserver TREXNameServer.cpp(12864) : matched host xxxx509 to xxxx301545c
i sr_nameserver TREXNameServer.cpp(15138) : volume 1 successfully initialized for system replication
i sr_nameserver TREXNameServer.cpp(15138) : volume 2 successfully initialized for system replication
i sr_nameserver TREXNameServer.cpp(15138) : volume 4 successfully initialized for system replication
i sr_nameserver TREXNameServer.cpp(15138) : volume 3 successfully initialized for system replication
Please note that when you add the replication server you’ll notice that you cannot open the Administration panel or run SQL queries. So you will not be able to check the data in the replication server.
Instead you are opening Diagnosis mode, below the screen cap shows the difference between the 2
Diagnosis Mode
Admin Panel
Click here for part 2
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