Different Instance on the Same Databse

[sudip]

Hi! All,
On Solaris box how can we have two instances running which are pointing to the same database.
Is having two separate int.ora files sufficient?

Regards
Sudip

[rohitsn]

Hi,
I think so that you are taking about Oracle Parallel Server(OPS).In OPS you have two instances pointing to the same database.

Instance A Instance B
\ /
Database

The main benefit of OPS comes into picture when you have Parallel Server running on cluster machines in which on both the machines you have two instances which accesses the datafiles on the external storage disks.The main advantage of this is evenif one of the instance crashes the other instances takesover the load on the crash instances and the users get automatically shifted to the working instance.
Yes ther are 2 different init.ora parameter files for both the instances but some the parameters are constant on both the nodes such as db_block_Size,gl_locks_to_file etc.
In case of any help please be free to ask me at rohitsn@altavista.com

Regards,
Rohit Nirkhe,Oracle DBA,OCP 8i
rohitsn@altavista.com

[sudip]

Yes, I was refering to the Oracle Parallel server. There are two things which still bug me
1) How does Oracle take care to Record locking?
2) Do each instance use the same control files?

[julian]

1) How does Oracle take care to Record locking?

In 8i, there is IDLM (Integrated Distributed Lock Manager).

In 9i, you have the Global Cache Service using the LMS background process. This concerns only DB resources. Non-DB-resources are managed by Global Enqueue Service and the LMD process.

2) Do each instance use the same control files?

Yes.





[Edited by julian on 01-22-2002 at 11:39 AM]