Virtual & Physical DB hostname

[Former Member]

Dear expert/GURU

1. In Production,We have cluster services in UNIX, with 2 nodes CI & DB.

My query is regarding virtual & physical DB host name. when i checked from SYSTEM->STATUS->Database data->HOSt-> it's pointing to physical DBhostname BUt Rz10->default profile->parameter SAPDBHOST->pointing to virtual DBhostname.

Moreover , in some activities we use Physical name, for others use virtual name. For eg:

a) to shutdown database we use physical DB name

b) T-code-DB13, execute Jobs using virtual Db name

2) In quality & development server, i found physical & virtual name are same, no such disprencies...

I totally confused, Please guide me...

Message was edited by: Sumit Jain

[Former Member · Accepted solution]

Hi Sumit,

As your production is running on cluster , it is obvious that you will have virtual Host names.As Dev and QA are not on clusters so you will be using only physical host names.

In Clusters you will have Primary and Secondary nodes. So whenever there is some fail in primary, Serivces will start in secondary. So using this virtual host names, Users will not get confused , moreover the system services will also start without any issues.

Virtual Hostname -> Primary Node( Different Physical host name) after fail over Same Virtual Host name -> Secondary node( Different Physical Host name).

Thanks,

Jagadish.

[Former Member · Accepted solution]

Virtual Hostname -> Primary Node( Different Physical host name) after fail over Same Virtual Host name -> Secondary node( Different Physical Host name).

   Hi jagdish,

  would help me understand above quoted lines....

[Former Member · Accepted solution]

Hi Sumit,

The basic concept of High availability is to the resources/servers for the user base should be available all the time.

So lets say in you cluster you have primary node with Physical host name A and secondary node with physical host name B.

So when you configure cluster you will use the virtual name lets say as VAB.

So this virtual name will be used by all the front ends for users and all.

So intially when the cluster is running on primary node this VAB is on physical host A. When failover happens this VAB is on physical host B.

So the user will not know anything about this internal config. Only user knows VAB which is virtual. They are not bothered about where it is running.

Please go through the concepts of Clustering and MSCS so that it will give you better understanding.

Thanks,

Jagadish.

[Former Member]

Hi Sumit,

What you found in production cluster is normal behaviour and so no worries. As for development and quality most likely you may not have a cluster and  therefore no virtual hostnames may have been. So only physical hostname is shown up.

Regards.

Ruchit.

[Former Member]

Dear Ruchit,

Thanks for answer...

Yes,there is no cluster in QAS & DEV

But, would you let me know, why virtual hostname is essential in cluster cervices

[Former Member]

Hi please could anyone explain me the concept of this virtual host name.I am having following configuration in ICL and i am new to SAP Basis.

(PAS-Primary application server)

(AAS-Additional Application server)

PAS host:=A                            

AAS-1 host:=B                          

PAS virtual hostname=C

AAS-1 virtual hostname=D

DB Server Node 1:=E

DB Server Node 2:=F

Virtual DB server:=G

what is the difference and use of this virtual and host name.

Thansk and Regards,

Akshay Jagtap

[Former Member]

Dear ALL,

  Please respond.....

[Former Member]

What?

[Former Member]

Hello Sumit,

The hostname must always point to only one entry and not multiple ones.(either physical or virtual)

Please check the following:
- the hostname in SM51
- in \etc\hosts in case you have multiple entries for the hostname
- the physical hostname at os level

Please refer the following notes to set the right hostname (physical or virtual)

129997 - Hostname and IP address lookup
23538 - Problems due to inconsistent host name
962955 - Use of virtual TCP/IP host names

All references to the hostname in SAP R/3 profiles (for example, SAPDBHOST, SAPLOCALHOST, SAPGLOBALHOST) must contain the TCP/IP host name!  
Use report RSPARAM to search for parameters using the hostname. If required adjust the hostname to the correct case and restart R/3, including SAP Services.
You can determine the TCP/IP host name by using the command line
command "hostname". Check the effectiveness of the changes by
displaying the host name in SM51.

Let me know if this helps!

Regards,

Sandhya

[Former Member]

Hi sandhya

  I think Jagdish & ruchit are correct. Bcoz my query is regarding virtual & physical database host names...