Installation on HA

[Former Member]

Hi ,

Installing NW7.3 ehp1 on HA.OS is linux.

Installation SCS on one node by using virtual Hostname and on second host ERS service will installed.

How enque server of SCS will SYNC ERS which i have installed on 2nd host.

If one nodeA will fail SCS will swtich to ERS on Node B?

How it will work?

[Former Member]

Hello Deepak Sir,

I have to install Java Based server ie PI 7.3 on H.A.

Planned system set like this :-

• Node A : SCS + CI , SCS and CI both will be on HA. As i dont need application server on Node B.
• Node B:- ERS + DB where DB on HA.
• Both server will have 2 virtual hostname and active passive state.If nodeA fail SCS and CI will move to Node B and id NodeB fail database will move to NodeA.
• SCS and Ci will install on virtual hostname on Node A and on Node B DB will install on Virtual Hostname and ERS will install on physical hostname on node B.

Pls Suggest !!!!

Regards

Adil

[ahmed_ibrahim2]

Dear Adil ,

kindly check the official Documents from RedHat and SUSE to install HA Service with Linux ,

check the Page no 7

ERS Service will be installed locally (you can assign Virtual host name and IP but the service will not move to the other node in case of fail over )

Deploying Highly Available SAP Servers using Red Hat Clustering -- Example

http://www.redhat.com/rhecm/rest-rhecm/jcr/repository/collaboration/jcr:system/jcr:versionStorage

/317745cf0a05260143c0ce…

installation with SUSE

http://www.novell.com/docrep/2012/07/sap_solutions_high_availability_on_SLES_for_sap_apps.pdf

Best Regards

AhMeD

Message was edited by: AhMeD IbRaHiM

[former_member188883]

Hi Adil,

As I see you plan to move CI instance as well during failover. In that case your setup looks correct.

Discuss the same with hardware vendor responsible for HA setup at OS level.

Keep all the mountpoints on SAN storage.

Regards,

Deepak Kori

[Former Member]

Dear Deepak Sir,

Thnx for ur all time expert Solution.One doubt .

As there will be two virtual IP in NodeA and NodeB .If Node A fails in and NOde B will UP.So the Hostname will be used in NOde B    http://hostname:50000  will be of virtual hostname of nodeB and vice-versa if Node B fails Node A will use Virtualhost name of node A.

Pls suggest Or there will be one common host name in any scenario whichever node fail.Because in URL while opening Page i think users will not change hostname everytime.As i m not doing LOad - Balancing also by web dispatcher!!!

Regards

Adil 

[former_member188883]

Hi Adil,

You need to have 2 virtual hostnames

One for DB and another for SCS+CI

When failover happens virtual hostname moves to another node.

For load balancing you may use Web Dispatcher.

Regards,

Deepak Kori

[ahmed_ibrahim2]

Dear Adil ,

Virtual Hostname (IP) is one of the service  resources to be assigned to that service , and the resources for each service will be active and running on the node carrying that service

example :for CI service you have to assign the following resources which should run in sequence during service running

1-     IP  ,assign the hostname in hosts file

2-     LVM ,which is control LVM availability in case you are using LVM

3-     FS ,the resource manage the mount point availability  

4-     SAP Instance or sap start script , to start sap instance

Best Regards

AhMeD

[Former Member]

Hi Ahmed,

Thnx for Guide . In that guide mention that ERS will not be part of cluster.And will be installed on locally on NODE B.when SCS and CI move from Node A to Node B in case of Node A failure SCS  will update ERS lock tables and ERS will shut down.

Is this way ERS will work?Should i need to shutdown ERS manually on NODE B.?

Regards

Adil

[former_member188883]

Hi Adil,

ERS starting and stopping should be part of cluster script. Check with hardware partner for the same.

Hope this helps.

Regards,

Deepak Kori

[ahmed_ibrahim2]

Hi Adil ,

Actually it is not the way

ERS service will install locally on one node but it will be managed by the cluster as long it is service , but there is some special requirement for that service

1- the ERS service will be locally installed you don't need LVM resource (no FS to be mounted ), resource required only IP , SAP Instance or script to start and stop the service

2- the important Part in that scenario is to let cluster stop the ERS  service after failover (after SCS moved to the node running ERS ) check the Event to be implemented in the guide page no 47 under "9.5.2 Service Dependencies"

check the steps below but adapt service name according to your conventional naming

1-edit the cluster.conf file to  enable central processing in the following Dir /etc/cluster/cluster.conf

2- add following Event at the end of the same file /etc/cluster/cluster.conf

3-also add the following two Events in that directory /usr/share/cluster

the name of the 1st event "event-service-ers.sl"

the name of the 2ed event "event-node-ers.sl"

also check the example of the Cluster.conf end of the guide

Best Regards

AhMeD

[ahmed_ibrahim2]

please , which tool you are using is it RedHat cluster ??

the previous events mentioned  will work with redhat cluster tools and exactly mentioned in the redhat guide

it will let ERS Service start and stop during failover automatically according to dependencies

Best Regards

AhMeD

[Former Member]

Hi Ahmed,

OS is SUSE and Cluster Service is Veritas storage foundation high availiblity.

Regards

Adil

[Former Member]

Hi,

I think For both Node need to install ERS on local?

Regards

Adil

[Former Member]

the below links should clear your doubt

[ahmed_ibrahim2]

Hi Adil ,

it is according your installation

1-  Enqueue Replication server can  install in one node if it will be manage by cluster SW,  and it can move to the other nodes if it is configured as cluster resource (but still, it will not run in the same node with SCS and in case if SCS Service Failover , ERS will move to another node or will stop if other nodes was down )

actually i prefer to install and configure ERS  as cluster resource

2 - if  polling concept used ==> ERS will install in all nodes in this scenario ERS will install locally and not move to any node

SAP Library - The SAP Lock Concept (BC-CST-EQ)

Polling Concept (SAP Library - The SAP Lock Concept (BC-CST-EQ))

check the guide from VCS how to handle ERS

http://kbdownload.symantec.com/resources/sites/BUSINESS/content/live/DOCUMENTATION/2000/DOC2760/en_U...

Best Regards

AhMeD

[former_member188883]

Hi Adil,

Message server will take care of holding the enque table entries when the local ERS system fails over.

System setup should be

Node A: DB + ASCS + CI

Node B: ERS + APP

Hope this helps.

Regards,

Deepak Kori