Shared or Dedicated server mode

My database is configured like:
9i Release2, Enterprise edition, OLTP, DEDICATED server mode!
I have more than 40 users who connect to db through WAN.
Is this good selection, I meen on server mode, or is better way to use SHARED s.mode. And way?!
Also where could I see which server mode of db is installed?
Thanks!

If we are talking about 40 physical end users, I wouldn't consider shared server mode. Shared server is ideal when you have so many users that the server would simply fall over if it tried to spawn that many dedicated connections.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

Similar Messages

Shared and Dedicated server modes

Hi,
We have been having some issues with connections and listeners. Please find here... Link [Post1|http://forums.oracle.com/forums/message.jspa?messageID=3665455] and Link [Post2|http://forums.oracle.com/forums/message.jspa?messageID=3677914].
Despite this help from this forum, I still face some problem configuring listener in both Shared and Dedicated server modes.
Pls find the below the problem...
Two listeners namely, LSNR1 and LSNR2 have been started.
listener.ora:
LSNR2 =
(DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = dbdev.website.org)(PORT = 1522))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
SID_LIST_LSNR2 =
(SID_LIST =
    (SID_DESC =
      (SID_NAME = TESTDB)
      (ORACLE_HOME = /u02/app/oracle)
LSNR1 =
(DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = dbdev.website.org)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
SID_LIST_LSNR1 =
(SID_LIST =
    (SID_DESC =
      (SID_NAME = TESTDB)
      (ORACLE_HOME = /u02/app/oracle)
)LSNR1 works with both Shared and Dedicated configurations, whereas LSNR2 neither DEDICATED nor SHARED configurations...
Here is the TNS names entry at the client (for LSNR2)...
serv2=
(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = xxx.xxx.xxx.xxx)(PORT = 1522))
    (CONNECT_DATA =
      (SERVICE_NAME=DEDICATED)
)When I try to connect using this, it says
+ ORA-12514: TNS: Listener does not know of service requested in connect descriptor +
Pls help.
Thanks,
Aswin.

Aswin,
I didnt see the other posts but the error is fairly simple,
>
ORA-12514:
TNS:listener does not currently know of service requested in connect descriptor
Cause:     The listener received a request to establish a connection to a database or other service. The connect descriptor received by the listener specified a service name for a service (usually a database service) that either has not yet dynamically registered with the listener or has not been statically configured for the listener. This may be a temporary condition such as after the listener has started, but before the database instance has registered with the listener.
Action:
- Wait a moment and try to connect a second time.
- Check which services are currently known by the listener by executing: lsnrctl services <listener name>
- Check that the SERVICE_NAME parameter in the connect descriptor of the net service name used specifies a service known by the listener.
- If an easy connect naming connect identifier was used, check that the service name specified is a service known by the listener.
- Check for an event in the listener.log file.
>
So check what you are passing in the connection string.
HTH
Aman....

How to convert dedicated server-mode to shared server-mode ?

Hi
I am having 3 oracle client machines(each with sql*plus or Toad tool),all these 3 client are to be connected through Jboss-4.0.5(application server) to Oracle 10g database server.
[ all 3 clients + 1 application server + 1 database server are with different ip address]
Question-1
Is it possible to convert a running Oracle-10.1.0.2.0 database server in[b] Windows server-2003 os from dedicated server-mode to shared server-mode ?
Question-2
What all are the init parameters I have to change ?
So far I have changed (a) alter system set shared_servers=5;
(b) alter system set dispatchers=(pro=tcp)(dis=3);
(c) alter system set max_dispatchers=10;
(d) alter system set shared_server_sessions=5;
(e) alter system set circuits=300;
Question-3
How to configure Listener in the Client system ?
Question-4
What all are the changes to be made in Jboss server ?
Regards
Sbmk_design

ad 1) Yes this is possible
Ad 2) From the top of my head, these seem like the settings to change
Ad 3) You do not have to change the listener (ow.. and clients have no listener) just make sure that you do not have '"server=dedicated" in your local tnsnames.ora file
Ad 4) in jboss, just check your datasource. If it is using a thin connection you are ok, if you are using a oci connection check the tnsnames.ora file.

Shared and Dedicated Server...

Dear All,
Can anybody tell what's the difference between shared and dedicated server? Our database is Oracle 9.0.1 in Windows 2003. Our total session is around 200. Our server is dedicated server. What will be the benefit if we change our database to shared server for specific users???
Shared pool size = 728MB
Buffer Cache = 592MB
Java pool = 104MB
Large pool = 60MB
There is no pga_aggregate_target in our database. Is the configuration ok for more than 200 users??? Most of the times we get 'out of process memory error'. What should we do in this situation??? Plz suggest.

mrashid07 wrote:
Can anybody tell what's the difference between shared and dedicated server?Dedicated server is the default. It means that each and every user session is serviced by a dedicated Oracle server process. 200 user connections? 200 dedicated server processes.
On Windows these are however threads inside the physical oracle.exe process (and not actual separate process images like on Unix/Linux for example). A standard thread on Windows needs around 2MB of kernel space. So 200 threads, for 200 dedicated server connections, need 200 x 2MB RAM.
Shared server works differently. A pool of dispatchers and shared servers are created. The dispatcher processes deals with the communication between the Oracle client and the Oracle instance. A dispatcher places client requests on a virtual circuit. These requests are picked up by idle shared server processes and processed. The results are send back to the client via a dispatcher process.
So instead of having 200 dedicated server processes to service 200 users, you can for example use 5 dispatcher processes and 30 shared server processes to service the 200 sessions of those 200 users. In this case 35 processes are used that translates into 35 threads at a basic 2MB RAM cost per thread. (also note that the UGA now moves from the Oracle PGA to the Oracle SGA and the SGA needs to be sized accordingly).
However, should such a user session send a long and complex request, that will tie up that shared server for a long time.. and this is bad. When the shared server process is busy, it cannot service any new requests. When all the shared servers in the pool are busy, no new request can be serviced. So you want the requests from the clients to be short and sweet - with a shared server not spending more than a few seconds per request.
So typically OLTP requests are fine for shared servers.. OLAP requests not.
Our database is Oracle 9.0.1 in Windows 2003. You should have been on 9.2.0.7 (last 9i patch set). You should currently being in the process of upgrading to 11gR2. 9i is basically an unsupported product. It is not a good idea to use an unsupported product in production. Even worse when you are not using the latest patchset for that product.
As for using Windows.. why? 32bit is old hat. 64bit CPUs are standard even in today's desktop PCs. Consider using Linux instead. It is Open Source, is free ito purchasing (you only pay for support and maintenance) and it has had de-facto 64bit support for many years now. There's no need to hack the operating system, like Windows with its AWE extensions to address more than 4GB RAM.

Shared vs dedicated server

Any reason to select one over the other?
The reason I'm asking is because two texts that I have which were not written by Oracle suggest using dedicated server processes, while all of the Oracle-written texts suggest shared (although I did finally find a note which mentions "NOTE:...if your machine has plenty of memory to support dedicated servers, you should use that approach. In this situation, performance is likely to be better.")
-cf

Actually it depends upon the requirement.
Shared and dedicated server environment are meant for different purposes and requirements.
If server process is ideal for long time than same server process can be used to server other clients. Eg. On a web site user searched for Oracle Tuning books and now he is taking time to go through the title, contents, price. Your Server process is ideal during this time where as it can used to server other clients.
Similarly if I use dedicated server process for batch processing it will be more effective than shared server because there is no ideal time.
It is not true shared server requires more resources or dedicated server requires more memory. It will depend upon the proper utilization of resources. With the same given resources dedicated server environment may work more efficiently for one scenario and in the another scenario with the same resources a shared server works very well.
Manu

Question regarding Listener and Server Processes in dedicated server mode

Good morning,
The Oracle documentation states that when a client connection request is received on the server, the Listener creates a Server Process which will work with the database instance to carry out the tasks requested by the user/client process. So far, everything good.
Now, when the user is at the Oracle server itself, the Listener does not need to be running to establish a connection to the database. It is therefore possible to stop the Listener and still connect using sqlplus and a valid username and password.
In the above case, the question is: if the Listener is not running, what/who created the Server Process that communicates with the database instance on behalf of the user ? Stated a different way, in the normal case, the Listener would get the request and create the server process. When the Listener is not running what part of Oracle gets the requests and creates the server process ?
Clarification on how this case is handled is much appreciated, thank you,
John.

When using bequeath protocol the server process is created by the client process: it's the client process that is using ORACLE_SID and ORACLE_HOME to compute shared memory key (under UNIX) to know which SGA to attach (i.e. which instance to connect to):
Example with SQL*Plus :
$ ps -fu oracle | grep DB112
oracle    5675     1 0 18:13 ?        00:00:00 ora_pmon_DB112
oracle    5677     1 3 18:13 ?        00:00:02 ora_vktm_DB112
oracle    5681     1 0 18:13 ?        00:00:00 ora_gen0_DB112
oracle    5683     1 0 18:13 ?        00:00:00 ora_diag_DB112
oracle    5685     1 0 18:13 ?        00:00:00 ora_dbrm_DB112
oracle    5687     1 0 18:13 ?        00:00:00 ora_psp0_DB112
oracle    5689     1 0 18:13 ?        00:00:00 ora_dia0_DB112
oracle    5691     1 0 18:13 ?        00:00:00 ora_mman_DB112
oracle    5693     1 0 18:13 ?        00:00:00 ora_dbw0_DB112
oracle    5695     1 0 18:13 ?        00:00:00 ora_lgwr_DB112
oracle    5697     1 0 18:13 ?        00:00:00 ora_ckpt_DB112
oracle    5699     1 0 18:13 ?        00:00:00 ora_smon_DB112
oracle    5701     1 0 18:13 ?        00:00:00 ora_reco_DB112
oracle    5703     1 0 18:13 ?        00:00:00 ora_mmon_DB112
oracle    5705     1 0 18:13 ?        00:00:00 ora_mmnl_DB112
oracle    5707     1 0 18:13 ?        00:00:00 ora_d000_DB112
oracle    5709     1 0 18:13 ?        00:00:00 ora_s000_DB112
oracle    5745     1 0 18:13 ?        00:00:00 ora_arc0_DB112
oracle    5747     1 0 18:13 ?        00:00:00 ora_arc1_DB112
oracle    5749     1 0 18:13 ?        00:00:00 ora_arc2_DB112
oracle    5751     1 0 18:13 ?        00:00:00 ora_arc3_DB112
oracle    5753     1 0 18:13 ?        00:00:00 ora_qmnc_DB112
oracle    5769     1 1 18:13 ?        00:00:00 ora_cjq0_DB112
oracle    5773     1 0 18:13 ?        00:00:00 ora_q000_DB112
oracle    5775     1 0 18:13 ?        00:00:00 ora_q001_DB112
oracle    5777     1 1 18:13 ?        00:00:00 ora_vkrm_DB112
oracle    5785     1 46 18:13 ?        00:00:24 ora_j003_DB112
oracle    5797 5796 2 18:14 ?        00:00:00 oracleDB112 (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle    5832 5801 0 18:14 pts/2    00:00:00 grep DB112
$ ps -fp 5796
UID        PID PPID C STIME TTY          TIME CMD
oracle    5796 5584 0 18:14 pts/1    00:00:00 sqlplusThis is also documented in 11.2 Net Admin. Guide http://download.oracle.com/docs/cd/E11882_01/network.112/e10836/concepts.htm#CIAFHAEE
>
If the client and database exist on the same computer, then a client connection can be passed directly to a dedicated server process without going through the listener. This is known as a bequeath protocol. The application initiating the session spawns a dedicated server process for the connection request. This happens automatically if the application used to start the database is on the same computer as the database.
>
Edited by: P. Forstmann on 5 sept. 2010 18:23

Shared or dedicated server

Dear all,
Would you tell me how to check out whether a database instance is a shared or a dedicated server?
Thanks

Firstly, thanks for your help.
I posted my problem in another thread. The problem is listed below.
BTW, when I create a new instance as dedicated server. I don't have this problem anymore.
So I wonder it is setting shared server is different from setting dedicated server.
Previous post:
===============================================================
I have a problem of network configuration. I installed an Oracle 8.1.7 standard edition database server. I can logon using sqlplus at local database machine without any problem. I can logon as system using sqlplus in a remote workstation, but I cannot logon using sqlplus as a normal user in a remote workstation. The normal user is granted connect role and create session system privilege.
Also, once I have a failed logon using normal user I cannot logon as system anymore until I restart the listener on the db server.
Please help. I don't have this problem on 9i, 10g.
The error is demostrated below:
===============================================================
SQL*Plus: Release 9.2.0.1.0 - Production on Fri Feb 24 21:45:11 2006
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle8i Release 8.1.7.4.0 - Production
JServer Release 8.1.7.4.0 - Production
SQL>
SQL> connect ars
Enter password: *****
ERROR:
ORA-12560: TNS:protocol adapter error
Warning: You are no longer connected to ORACLE.
SQL> connect system
Enter password: *******
ERROR:
ORA-12560: TNS:protocol adapter error
===============================================================
The listener.ora, sqlnet.ora in the server is listed below:
===============================================================
# LISTENER.ORA Network Configuration File: /u01/app/oracle/product/8.1.7/network/admin/listener.ora
# Generated by Oracle configuration tools.
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 172.20.2.18)(PORT = 1521))
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = /u01/app/oracle/product/8.1.7)
(PROGRAM = extproc)
(SID_DESC =
(GLOBAL_DBNAME = stustg.urban.com.hk)
(ORACLE_HOME = /u01/app/oracle/product/8.1.7)
(SID_NAME = stustg)
===============================================================
# SQLNET.ORA Network Configuration File: /u01/app/oracle/product/8.1.7/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.
#SQLNET.AUTHENTICATION_SERVICES= (NONE)
NAMES.DIRECTORY_PATH= (TNSNAMES)
===============================================================

Not able to get Shared Server Mode to work in XE

The server is an HP Dual CPU Xeon, 4 GB RAM. 120GB HD.
Oracle XE reports the following:
SGA 768 Target, 768MB Current.
PGA 256MB Target, 55MB current (when there are a small number of client connections)
The application and database work properly with a small number of connections, but
memory usage goes way up on PGA when I start to add more connections.
I have tried to set up the Oracle server in "Shared Server Mode" , but it appears
that I was unsuccessful.
From what I can tell, the oracle listener does not seem to be fowarding the incoming requests to the shared server dispatchers, but
instead it is deciding to kick off a dedicated server process to handle each client request.
In other words, it is working in dedicated server mode.
I am stumped as to what needs to be done next. From what
I can tell from reading documentation this should be working.
Please advice as to what else I can do to get things working.
Here is additional information:
The parameter SHARED_SERVERS is equal to 4.
parameter dispatchers=(PROTOCOL=TCP) (SERVICE=XEXDB)
max_shared_servers, max_dispatchers, shared_server_sessions have no values.
processes=150
sessions=170
Output of lnsrctl utility:
LSNRCTL> services
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC_FOR_XE)))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0
LOCAL SERVER
Service "PLSExtProc" has 1 instance(s).
Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0
LOCAL SERVER
Service "XEXDB" has 1 instance(s).
Instance "xe", status READY, has 1 handler(s) for this service...
Handler(s):
"D000" established:0 refused:0 current:0 max:1002 state:ready
DISPATCHER <machine: CO_DB, pid: 5844>
(ADDRESS=(PROTOCOL=tcp)(HOST=myhostname)(PORT=1771)
Service "XE_XPT" has 1 instance(s).
Instance "xe", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
LOCAL SERVER
Service "xe" has 1 instance(s).
Instance "xe", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
LOCAL SERVER
The command completed successfully
ILSNRCTL> status
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC_FOR_XE)))
STATUS of the LISTENER
Alias LISTENER
Version TNSLSNR for 32-bit Windows: Version 10.2.0.1.0 - Produ
ction
Start Date 18-SEP-2007 16:06:55
Uptime 0 days 0 hr. 1 min. 33 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Default Service XE
Listener Parameter File E:\oraclexe\app\oracle\product\10.2.0\server\network\a
dmin\listener.ora
Listener Log File E:\oraclexe\app\oracle\product\10.2.0\server\network\l
og\listener.log
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC_FOR_XEipc)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=myhostname)(PORT
=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=8080))(Presentation=
HTTP)(Session=RAW))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "PLSExtProc" has 1 instance(s).
Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "XEXDB" has 1 instance(s).
Instance "xe", status READY, has 1 handler(s) for this service...
Service "XE_XPT" has 1 instance(s).
Instance "xe", status READY, has 1 handler(s) for this service...
Service "xe" has 1 instance(s).
Instance "xe", status READY, has 1 handler(s) for this service...
The command completed successfully
The contents of the spfile2init.ora file:
xe.__db_cache_size=104857600
xe.__java_pool_size=4194304
xe.__large_pool_size=469762048
xe.__shared_pool_size=222298112
xe.__streams_pool_size=0
*.audit_file_dest='E:\oraclexe\app\oracle\admin\XE\adump'
*.background_dump_dest='E:\oraclexe\app\oracle\admin\XE\bdump'
*.compatible='10.2.0.1.0'
*.control_files='E:\oraclexe\oradata\XE\control.dbf'
*.core_dump_dest='E:\oraclexe\app\oracle\admin\XE\cdump'
*.db_name='XE'
*.db_recovery_file_dest='f:\oracle_flash_recovery_area'
*.db_recovery_file_dest_size=42949672960
*.dispatchers='(PROTOCOL=TCP) (SERVICE=XEXDB)'
*.job_queue_processes=4
*.open_cursors=300
*.os_authent_prefix=''
*.pga_aggregate_target=268435456
*.processes=150
*.remote_login_passwordfile='EXCLUSIVE'
*.sessions=20
*.sga_target=805306368
*.shared_servers=4
*.undo_management='AUTO'
*.undo_tablespace='UNDO'
*.user_dump_dest='E:\oraclexe\app\oracle\admin\XE\udump'
The contents of listener.ora:
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = E:\oraclexe\app\oracle\product\10.2.0\server)
(PROGRAM = extproc)
(SID_DESC =
(SID_NAME = CLRExtProc)
(ORACLE_HOME = E:\oraclexe\app\oracle\product\10.2.0\server)
(PROGRAM = extproc)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
(ADDRESS = (PROTOCOL = TCP)(HOST = myhostname)(PORT = 1521))
DEFAULT_SERVICE_LISTENER = (XE)
The contents of tnsnames.ora
XE =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = myhostname)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = XE)
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
ORACLR_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
(CONNECT_DATA =
(SID = CLRExtProc)
(PRESENTATION = RO)
The contents of sqlnet.ora:
# This file is actually generated by netca. But if customers choose to
# install "Software Only", this file wont exist and without the native
# authentication, they will not be able to connect to the database on NT.
SQLNET.AUTHENTICATION_SERVICES = (NTS)

I don't think it is supported because of XE multiple cpu usage limitations but "shared server" is not documented in the XE documentation - http://www.oracle.com/pls/xe102/ranked?word=%22shared+server%22
so you may want to follow this guide for setup and try -
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/manproc.htm#ADMIN00502
Best Regards,
H.Tonguç YILMAZ
My Oracle blog
http://tonguc.wordpress.com
"Never believe all you read or hear! Just because it is printed or someone is more experienced doesn't mean it is TRUE.."

Dedicated server/shared server

Hi everyone,
can you Explain me about the shared server/dedicated server mode .
THANKS IN ADVANCE

think of the oracle server process as a genie- the magical being from the story of Aladdin-because your wish for a oracle data is the server process command-
dedicated server(one genie one master):-_in this setup every single user connecting to oracle will have a personal genie handling data retrieval from disk in to buffer cache. if there are 120 users connecting to oracle there will also be 120 genies out there grabbing data from disk and putting it in the buffer cache for those user. this architectural setup means that every user gets his or her data retrieval requests acted upon immediately. it also means there will be additional memory and cpu overhead on the mechine running the oracle database.
shared server:-(one genie one master):-* in this setup there is a small pool of server process running in oracle that supports data retieval requests for a large number of users. several users are served by one server process.if there are 120 users connecting to oracle there will be only 1 genie out there for grabbing data from disk and putting it in the buffer cache for those user.

Converting from dedicated server to shared server

Hi,
How to convert from a dedicated server configuration to a shared server configuration.
Thanks
Muneer

SHAN@2009 wrote:
Hi
I am using Oracle 11g Database Release 1 OS Windows 2003 Server R2 SP2, I have Created a Database and the database server mode is "Shared' recently my user request me to change server mode into Dedicated for there testing Purpose.what are the Parameters i have set in the ini file for converting the server mode from Shared to Dedicated.
Please advice .
Thanks
ShanIt's not an either/or situation, as the database does not "run in shared server mode" vs. "run in dedicated server mode". A database will *always* accept dedicated connections if requested by the client. It *may* accept shared server connections -- *if* requested by the client *and if* it is configured to accept them.

Different between shared server and dedicated server

could you explain difference between shared server and dedicated server.

Oracle has two modes, a shared server mode and a dedicated server mode. In dedicated server mode (the default), the Oracle server creates one process per connection.
This quickly limits the number of connections the Oracle Server can support due to the following:
1.There is an OS limit on how many processes/file descriptors can be supported
2.Oracle has an internal PROCESSES parameter that prevents it from launching more than the specified number of processes.
When it is anticipated that these limits may be exceeded, which frequently happens for 50-100 concurrent connections, you should either configure Oracle in shared server mode or increase the limits above, so that many concurrent connections can be supported by each Oracle process. Oracle states that running in shared server mode is slightly slower than in dedicated server mode.

Dedicated server question

If database was crated in DEDICATED SERVER mode and still is, why then I have SHARED_SERVERS parameter set to 1 and shared server process running on my server? This is only database on this server.
# ps ax | grep s0
4412 ? Ss 0:00 ora_s000_PROD
Oracle 10g, Linux x86

On a stand-alone laptop with dedicated connection running 11.1.0.7.
SQL> select name, status, idle, busy, requests
2 from GV_$SHARED_SERVER;
NAME                           STATUS                 IDLE       BUSY   REQUESTS
S000                           WAIT(COMMON)           9085          0          0
SQL> What you see is what is expected for a dedicated connection.
What is in your TNSNAMES.ORA?
Here's mine:
ORABASE =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orabase)
)for comparison purposes.

Server mode

what is the difference between dedicated server mode and shared server mode.

In Shared Server : you have a SGA for all users and all resources are shared.
In dedicated Server : each user has its own memory and process. ( This option is good for few users )
Joel P�rez

Can i backup dedicated server using rman?

when i try to issure 'register database' under rmank, it report and error:
RMAN-10035: exception raised in RPC: ORA-19550: cannot use backup/restore functi
ons while using dispatcher
RMAN-10031: ORA-19550 occurred during call to DBMS_BACKUP_RESTORE.CFILEUSECURREN
i configure my oracle using MTS(multi-thread server) mode. When i change it to Dedicated Server mode, it works without error.
does that rman can only work with dedicated server? How about MTS?
thanks.

Here is a section in the RMAN docs that explain MTS and RMAN.
http://otn.oracle.com/docs/products/oracle9i/doc_library/release2/server.920/a96566/rcmconfg.htm#450732
Thanks, Tammy

How fast a query can run on dedicated server?

I have a server on which we have installed several clients database isntances. Recently there were several performance issue for one of the client while running few reports at which time I heard that was becasue of their instance is an shared server and if we make it dedicated the performance will improve. How do you find out whether an instance running on a particular box is a dedicated server connection or shared server connection. What is the definition of those in simple lay mans terms. How do you change a shared connection to dedicated connection and vice versa? Does it depend on the memory/cpu size etc. Changing it to dedicated server helps the performance? if so by how much Any help is higly appreciated.

user5846372 wrote:
I have a server on which we have installed several clients database instances. Recently there were several performance issue for one of the client while running few reports at which time I heard that was because of their instance is an shared server and if we make it dedicated the performance will improve. I start to reach for the old lead pipe when I hear stuff like that, that is seemingly based on hearsay and rumour and not a single shred of evidence is provided.
I will tell "+those people+" that claims your performance problems are due to shared server to put up or shut up.
There is very little performance difference (in the vast majority of cases) between shared and dedicated server. The biggest difference is that with a shared server you talk to the process servicing your SQL via a dispatcher process and then via a virtual circuit. With a dedicated server, you talk directly to the process servicing you.
Both shared and dedicated server runs the SAME CBO code , the SAME SQL engine.. so how can a query be faster in one and not the other? And if that was the case. If there was a performance difference.. Surely Oracle will recommend not using the "bad" one? Or even better, Oracle would discontinue and deprecated the "bad" one?
There is no difference in whether a query is executed by shared or dedicated server. The same CBO does the same execution plan and creates the same cursor. What is different is how the communication and interaction works with the client session/process. What is different is where UGA (User Global Area) memory resides. In other words, very technical execution environment differences - not differences to HOW the query is parsed and HOW the query is executed. Which then begs the question how can the query be faster in one and not the other?
But shared server and dedicated server aside. What is the "+First and Fundamental Rule Of Software Engineering?+"
It is.. "{color:blue}*UNDERSTAND THE PROBLEM*{color}"
If you do not know WHAT the problem is, WHY the problem is, how on earth can you hope to address the problem and resolve it?
Thus my "unhappiness" of those that make performance resolution claims by sucking their thumbs, repeating what they may have read somewhere, and not back it up with evidence and fact - like those who told you that your problem is using shared server.
What can be a problem is that you may not have enough dispatchers. Or insufficient shared servers in the shared server pool. Or being to tight with the SGA that now also needs to cater to the shared server sessions' UGA memory. Or shared servers being used (incorrectly and explicitly by client software) for running long and slow queries (thus tying up that shared server with servicing a single session and making it non-sharable and unable to service others too). Etc. Etc.
There's a whole wackload of potential issues... and many of them are solved in different ways. Simply changing shared server for dedicated servers and expecting a performance improvement as those hearsayers you deal with are claiming...? That is not just ignorance, but borders dangerously on stupidity. (dedicated servers can also kill performance when incorrectly used)

Shared or Dedicated server mode

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