2 INSTANCES IN ONE M/C?

Hi

Recently I was asked in an interview, if u can have 2 instances running in one m/c at the same time?

Can u answer, please?

Thanks

ggnanaraj

What is an m/c?

What is the m/c ? Machine ? you mean Box ?

If so, what OS ? Yes! you can have as many as you want if you have resources on the box. I have 8 instance running on Solaris 2.6 box.

Thanks for the reply.

What I now infer is that it is possible to have more than 1 instance running on the same machine(m/c) at the same time. So each instance can have its own database(s) also running? right?

What about NT os?

Thanks.

instance/database------> Normal configuration
instances/database----> OPS(Oracle Parrallel Server)

Sure, Even in NT if you enough memory, you can support more than one instances.

Nizar

U can always no of instances u want ,i had discussion reg this recently

Thanks
lnr

I have a basic question...
Here is the text from tnsnames.ora file.

ORCL1.WORLD =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = NMP)(SERVER = tree)
(PIPE = ORAPIPE))
(CONNECT_DATA = (SID = TEST))
)

orcl2.WORLD =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = NMP)(SERVER = tree)
(PIPE = ORAPIPE))
(CONNECT_DATA = (SID = SUP))
)

As you can see these 2, orcl1 and orcl2 are on the same server.
are SUP and TEST the instance names ?
are orcl1 and orcl2 different databases on same server ?

Thanks
Sonali

orc1, orc2 are the service names(connection strings) to connect to databases SUP and TEST. You can have 10 services names starting from orc01 to orc10...pointing to SUP/TEST.

You are confused with service names and database names. tnsnames.ora deals with service names.

Hi,

You can have any number of instances, for memory resource, you can create one home and create multiple instance in that home, The name will be different. And for accessing the instance, use the sid name.

With regards

Sreddy, you write

instance/database------> Normal configuration
instances/database----> OPS(Oracle Parrallel Server

Could you clarify? I'm still new to Oracle and the distinction between intance and database is still not very clear for me. :-(

I know it's probably a newbie question, but I have to start somewhere no? :-)

Thanks!!

I prefer to rephrase

instance per database------> Normal configuration
instances per database----> OPS(Oracle Parrallel Server

sorry about the confusion.

Look at :

Instance as only back ground processes PMON, SMON,DBWR,LGWR etc., and SGA.

Database as datafiles,tablespaces,tables etc which has data in it.

[Edited by sreddy on 01-23-2001 at 04:50 PM]

Thanks for clarification sreddy! Yes, I am little bit confused with the instance !
I know this is a basic question, but what is the instance then ??
I thought that SID in tnsnames.ora is the instance ID which should be unique.
So I was thinking that each service is a instance and that the database can have multiple instances/services on the same server. Is their any limit on how many services you can have for a database ?

SID (System Identifier) is an instance(SGA+background processes like PMON,SMON.DBWR,LGWR,CKPT) assoicated with the database(physical data files and logical tablespaces,tables etc, which stores the actual data).

ORCL1.WORLD =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = NMP)(SERVER = tree)
(PIPE = ORAPIPE))
(CONNECT_DATA = (SID = TEST))
)

orcl2.WORLD =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = NMP)(SERVER = tree)
(PIPE = ORAPIPE))
(CONNECT_DATA = (SID = SUP))
)

orcl1 and orcl2 are two net service names (aliases) on the same server tree connecting to two different SID`s SUP and TEST.
SUP and TEST are two instance names or SID`s associated with two diffrent databases?
Hope this helps. If doesn't try to follow the link and analyze.

http://technet.oracle.com/doc/window...apc.htm#449105







[Edited by sreddy on 01-23-2001 at 04:48 PM]

Yes it kind of a confusion at times on what people mean by database and instance. Here are some of the past threads that is worth the spending some time to look
http://www.dbasupport.com/forums/sho...?threadid=3421


http://www.dbasupport.com/forums/sho...?threadid=3490


http://www.dbasupport.com/forums/sho...?threadid=3781

Good luck.

Sam