Find undo tablespace assignment in RAC

Hi Experts,
We have 6 nodes 10GR2 rac database. It seems that does not assign each instance order with undo tbs.
How can I find each instance assigned undo tablespace?
Thanks very much!
JIm

Handle:      user589812
Status Level:      Newbie
Registered:      Aug 13, 2007
Total Posts:      829
Total Questions:      366 (338 unresolved)
so many questions & so few answers.
also Do i have a way to drop a datafile in undo tablesapce?UNDO is no different than any other tablespace.

Similar Messages

Why do 2 diff. undo tablespace required in RAC

Hi -
1 - I can understand that we do require 2 diff. log files as 2 process can not write on the same redo log files.
But I could not understand the logic of using 2 diff. undo tablespaces, when tablespaces can be in shared mode.
They what is the reason of using 2, why can we not have only one undo tablespace in RAC.
2 - Is there any way to check if one particular instance is running under RAC, Can this be confirmed if instance
has got extra process like Lms Lmd ...
your help would be appreciated and apologies for my poor english.
Regards,
Lyxx

Each instance needs its own rollback segments to manage read consistency.
When you set undo_tablespace=UNDOTBS, you tell the instance to self manage the tablespace UNDOTBS and do dynamic creation of rollback segments.
This management of undo tablespaces is not "instance shareable". That's why you need 2 undo tablespace (for a 2 node RAC).
If it's a problem for your environment (don't know why), you can create a single "rollback tablespace" and manage yourself the rollback segments.
Christophe
Edited by: willier on 11 sept. 2008 02:44

Second Undo Tablespace in Oracle10g v.2...

Hi ,
Having connected as sys i created another undo tablespace ... except for the first one created by default....
SQL> CREATE UNDO TABLESPACE INFO_UNDO_TBL DATAFILE 'C:\oracle\product\10.2.0\oradata\INFO\INFO_UNDO_DFL.ORA' SIZE 10M;
Tablespace createdI have two questions...
1) When i issue the command:
SQL> SHOW PARAMETER UNDO_TABLESPACE;
NAME                                 TYPE        VALUE
undo_tablespace                      string      UNDOTBS1It does not refer the new undo tablespace..... I suppose that i have to write:
sql> alter system set undo_tablespace=UNDOTBS1,INFO_UNDO_TBL scope =BOTH... or something like this....Is that correct....??????
2)The Oracle Doc (Concepts) points out.....
"In automatic undo
management mode, each Oracle instance is assigned one (and only one) undo
tablespace."
That means i cannot issue the command "alter system set undo_tablespace=UNDOTBS1,INFO_UNDO_TBL" (if it is correct) since the default undo tablespace runs in AUTO mode.....????
SQL> SHOW PARAMETER UNDO_MANAGEMENT;
NAME                                 TYPE        VALUE
undo_management                      string      AUTOMany thanks....
Sim

Hi ,
I dont think you can have two undo tablespaces assigned for a database.This is what you get in the alert log files even if you are deceived by the statement "System Altered"
SQL> alter system set undo_tablespace='UNDOTBS1,UNDOTBS2' scope=spfile;
System altered.
SQL> sho parameter undo
NAME TYPE VALUE
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS1,UNDOTBS2
Alert log extract..............
Errors in file j:\oracle\product\10.2.0\admin\orcl10g\udump\orcl10g_ora_1724.trc:
ORA-30012: undo tablespace 'UNDOTBS1,UNDOTBS2' does not exist or of wrong type
Errors in file j:\oracle\product\10.2.0\admin\orcl10g\bdump\orcl10g_reco_1808.trc:
ORA-30012: Message 30012 not found; No message file for product=RDBMS, facility=ORA
Tue Oct 02 15:37:41 2007
Errors in file j:\oracle\product\10.2.0\admin\orcl10g\bdump\orcl10g_smon_1760.trc:
ORA-30012: Message 30012 not found; No message file for product=RDBMS, facility=ORA
Instance terminated by USER, pid = 1724
ORA-1092 signalled during: alter database open...
Regards,
-Praveen
http://myracle.wordpress.com

Undo tablespace in RAC

hi all,
In RAC environment, if iam having two nodes, why i have to maintain two undotablespaces in shared area? is it not possible to use one undo tablespace for both the instances instead of two undo tablespaces?
thank you

Hello Buddy,
It is not possible use one UNDO tablespace for more than one instance in RAC architecture.
Unless that you implement rollback segs (forget it, totally unrecommended), then the entire database can use only one rollbackseg on shared storage.
You must maintain unless one undo tbs per instance on your cluster database cause consistent reads on local instances.
Best Regards,
Rodrigo Mufalani
http://mufalani.blogspot.com

Is it OK to Switching Undo Tablespaces without DB stop ?

We use Oracle11g R2.
I read Oracle Doc and It looks OK.
But, how could I make sure UNDO tablespace mode(ONLINE,PENDING OFFLINE) ?
Switching Undo Tablespaces
You can switch from using one undo tablespace to another. Because the UNDO_TABLESPACE initialization parameter is a dynamic parameter, the ALTER SYSTEM SET statement can be used to assign a new undo tablespace.
The following statement switches to a new undo tablespace:
ALTER SYSTEM SET UNDO_TABLESPACE = undotbs_02;
Assuming undotbs_01 is the current undo tablespace, after this command successfully executes, the instance uses undotbs_02 in place of undotbs_01 as its undo tablespace.
If any of the following conditions exist for the tablespace being switched to, an error is reported and no switching occurs:
The tablespace does not exist
The tablespace is not an undo tablespace
The tablespace is already being used by another instance (in an Oracle RAC environment only)
The database is online while the switch operation is performed, and user transactions can be executed while this command is being executed. When the switch operation completes successfully, all transactions started after the switch operation began are assigned to transaction tables in the new undo tablespace.
The switch operation does not wait for transactions in the old undo tablespace to commit. If there are any pending transactions in the old undo tablespace, the old undo tablespace enters into a PENDING OFFLINE mode (status). In this mode, existing transactions can continue to execute, but undo records for new user transactions cannot be stored in this undo tablespace.
An undo tablespace can exist in this PENDING OFFLINE mode, even after the switch operation completes successfully. A PENDING OFFLINE undo tablespace cannot be used by another instance, nor can it be dropped. Eventually, after all active transactions have committed, the undo tablespace automatically goes from the PENDING OFFLINE mode to the OFFLINE mode. From then on, the undo tablespace is available for other instances (in an Oracle Real Application Cluster environment).

After you switch the UNDO_TABLESPACE parameter to the new tablespace, at the minimum, you have to wait for active transactions to complete (commit/rollback) before you can take the old Undo Tablespace offline. Note that if you take the old Undo Tablespace offline too quickly, you may prevent long running queries from reading from the old Undo Tablespace and may cause them to error with ORA-01555. So you need to wait a reasonable time (e.g look at MAXQUERYLEN in V$UNDOSTAT) before you take the old Undo Tablespace offline.
Hemant K Chitale

Undo Tablespace queries

Hi All,
I am bit confused with reading about the undo table space. so i need some clarification
1. There are 2 undo tablespace in our application. Could someone explain how the 2 undo tablespace works? I didn't find any details about this.
2. Both the undo tablespace is 100% utilized. Where the the new transaction will go? Will new transaction force the used blocks to be expired if needed?
3. What should be the ideal size of undo tablespace with respect to the total storage size?
4. is Archive log related to undotable space? if yes then When the archive logs get generated?
Thanks

1. In an RAC database, each Instance has to have it's own Undo Tablespace.
In a non-RAC (single instance) database, only one Undo Tablespace may be active at any time. The other Undo Tablespace would be inactive but can be switched to with an ALTER SYSTEM SET UNDO_TABLESPACE command.
2. Even if an Undo Tablespace is "100% used" Oracle can expire (and even drop) old extents and segments that are no longer needed by the Undo_Retention value. Thus, undo data for older transactions that have committed (more than Undo_Retention period has elapsed since the commit) will be overwritten.
3. There's no "ideal size". Undo sizing is based on Transaction volumes, fluctuations in transaction volumes, query patterns etc.
4. No, there is no direct relation between the two. However, all Undo that is generated also is written to Redo -- i.e. Redo captures Undo as well as it captures changes to Tables, Indexes etc.
I suggest that you read the Oracle Concepts documentation at
http://download.oracle.com/docs/cd/E11882_01/server.112/e16508/toc.htm
Hemant K Chitale
http://hemantoracledba.blogspot.com

Separate UNDO tablespace for each instance

Version: 10.2.0.4, 11.2.0.2
I've noticed that there is an UNDO tablespace for each instance in RAC. Since UNDO tablespace lies in the shared storage, isn't it better to have just one UNDO tablespace for all instances?

Max wrote:
Version: 10.2.0.4, 11.2.0.2
I've noticed that there is an UNDO tablespace for each instance in RAC. Since UNDO tablespace lies in the shared storage, isn't it better to have just one UNDO tablespace for all instances?Each instance in the RAC system can only use one undo tablespace at a time. In other words, instances cannot share undo tablespaces. Each instance in the cluster, being an independent transaction-processing environment, maintains its own UNDO area for undo management.
Either automatic undo management or rollback segment undo can be used to manage undo space. If the automatic rollback method will be used, set the global parameter undo_management to auto in the server parameter file, and set the undo_tablespace parameter to assign the undo tablespace to the instance.
The RAC system allows the creation and use of several undo tablespaces. When the instance is started, it uses the first available undo tablespace. A second instance will use another undo tablespace. Thus, each instance in a RAC system will have exclusive access to a particular undo tablespace at a given time. The undo tablespace cannot be shared among the instances at the same time. Only once an undo tablespace is released by an instance, it can be assigned to another instance. However, all instances can read blocks from any or all undo tablespaces for the purpose of constructing read-consistency images.
source:http://www.dba-oracle.com/real_application_clusters_rac_grid/undo_management.htm

Regarding Maxsize of Undo Tablespace

Dear expetrs
While executing a procedure i got error.
Error In Insertion..ORA-30036: unable to extend segment by 16384 in undo tablesp
ace 'UNDOTBS1'
then i increase the size of the Undo Tablespace
then again i got error.
ORA-01144: File size (7680000 blocks) exceeds maximum of 4194303 blocks
plz give me answer as soon as possible.
thnaks.

1) resize your datafile to 4194303 * db_block_size
alter database datafile < path/filename > resize <4194303 * db_block_size> ;
you find db_block_size by:
sqlplus /nolog
SQL> connect / as sysdba
SQL> show parameter db_block_size
or by simply have a look in the pfile (init<SID>.ora) in $ORACLE_HOME/dbs
2) add another file to the undo tablespace:
SQL>alter tablespace undotbs1 add datafile <path/filename> size <n> M;
a tablespace may have up to 1022 datafiles.
hope this helps
roman

Cannot drop undo tablespace

Hello:
I've created a new undo tablespace undotbs2. I've set it to the default undo tablespace. When I've tried to drop the old one, I get the following error:
SQL> conn / as sysdba
Connected.
SQL> DROP TABLESPACE undotbs1 INCLUDING CONTENTS AND DATAFILES;
DROP TABLESPACE undotbs1 INCLUDING CONTENTS AND DATAFILES
ERROR at line 1: ORA-01548: active rollback segment '_SYSSMU7$' found, terminate dropping tablespace
This is a production database. The service is down because the partition with the Oracle tablespaces: system, undo, temp, etc is full.
After shutting down the database the problem persist: I cannot drop the old undo tablespace because of the same error.
I've followed the note 1321093.1. Here the query results:
Select segment_name, status, tablespace_name, rs.segment_id
from dba_rollback_segs rs
where status not in ('ONLINE','OFFLINE');
_SYSSMU7$ PARTLY AVAILABLE UNDOTBS1 7
SELECT KTUXEUSN, KTUXESLT, KTUXESQN, /* Transaction ID */ KTUXESTA Status, KTUXECFL Flags
FROM x$ktuxe
WHERE ktuxesta !='INACTIVE' AND ktuxeusn =7;
7 47 382687 ACTIVE DEAD
SELECT LOCAL_TRAN_ID,GLOBAL_TRAN_ID,STATE,MIXED,COMMIT# FROM DBA_2PC_PENDING;
No rows
SELECT LOCAL_TRAN_ID,IN_OUT,DATABASE,INTERFACE FROM dba_2pc_neighbors;
No rows
As you can see, there is no pending transactions. No application is connected to the database (service is down), however the database is appling rollbacks since 2 days.
A lot of archivelogs are being created at rolling back (30 GB archivelogs per hour). Here a tail of the alertlog file:
Wed Apr 17 06:19:53 2013
Thread 1 advanced to log sequence 7382
Current log# 5 seq# 7382 mem# 0: /ora2/origlogs/webfrbr/redo05_m1.log
Current log# 5 seq# 7382 mem# 1: /ora3/mirrorlogs/webfrbr/redo05_m2.log
Wed Apr 17 06:21:16 2013
Thread 1 advanced to log sequence 7383
Current log# 6 seq# 7383 mem# 0: /ora2/origlogs/webfrbr/redo06_m1.log
Current log# 6 seq# 7383 mem# 1: /ora3/mirrorlogs/webfrbr/redo06_m2.log
Wed Apr 17 06:22:41 2013
Thread 1 advanced to log sequence 7384
Current log# 4 seq# 7384 mem# 0: /ora2/origlogs/webfrbr/redo04_m1.log
Current log# 4 seq# 7384 mem# 1: /ora3/mirrorlogs/webfrbr/redo04_m2.log
Wed Apr 17 06:24:02 2013
Thread 1 advanced to log sequence 7385
Current log# 5 seq# 7385 mem# 0: /ora2/origlogs/webfrbr/redo05_m1.log
Current log# 5 seq# 7385 mem# 1: /ora3/mirrorlogs/webfrbr/redo05_m2.log
Wed Apr 17 06:25:24 2013
Thread 1 advanced to log sequence 7386
Current log# 6 seq# 7386 mem# 0: /ora2/origlogs/webfrbr/redo06_m1.log
Current log# 6 seq# 7386 mem# 1: /ora3/mirrorlogs/webfrbr/redo06_m2.log
Wed Apr 17 06:26:46 2013
Thread 1 advanced to log sequence 7387
Current log# 4 seq# 7387 mem# 0: /ora2/origlogs/webfrbr/redo04_m1.log
Current log# 4 seq# 7387 mem# 1: /ora3/mirrorlogs/webfrbr/redo04_m2.log
Oracle Database - Enterprise Edition 10.2.0.3
Linux x86-64 Oracle Linux 5
Please, consider the output of the following queries too:
select * from V$FAST_START_TRANSACTIONS
USN 7 -- Undo segment number of the transaction
SLT 47 -- Slot within the rollback segment
SEQ 382687 -- Incarnation number of the slot
STATE RECOVERING --
UNDOBLOCKSDONE 0 -- Number of undo blocks completed on the transaction
UNDOBLOCKSTOTAL 2079151 -- Total number of undo blocks that need recovery
PID 15 -- ID of the current server it has been assigned to
CPUTIME 1153 -- Time for which recovery has progressed (in seconds)
PARENTUSN 0 -- Undo segment number of the parent transaction in PDML
PARENTSLT 0 -- Slot of the parent transaction in PDML
PARENTSEQ 0 -- Sequence number of the parent transaction in PDML
XID 07002F00DFD60500 -- Transaction ID
PXID 0000000000000000 -- Parent transaction ID
RCVSERVERS 1 -- Number of servers used in the last recovery
select * from x$ktuxe where ktuxecfl = 'DEAD';
ADDR 00002B3E808B9BD8
INDX 145
INST_ID 1
KTUXEUSN 7
KTUXESLT 47
KTUXESQN 382687
KTUXERDBF 2
KTUXERDBB 2080076
KTUXESCNB 424110769
KTUXESCNW 0
KTUXESTA ACTIVE
KTUXECFL DEAD
KTUXEUEL 3739
KTUXEDDBF 0
KTUXEDDBB 0
KTUXEPUSN 0
KTUXEPSLT 0
KTUXEPSQN 0
KTUXESIZ 2079151
select * from v$fast_start_servers;
RECOVERING 0 15 07002F00DFD60500
IDLE 0 16 0000000000000000
IDLE 0 17 0000000000000000
IDLE 0 18 0000000000000000
IDLE 0 19 0000000000000000
IDLE 0 20 0000000000000000
IDLE 0 21 0000000000000000
IDLE 0 22 0000000000000000
IDLE 0 25 0000000000000000
IDLE 0 26 0000000000000000
IDLE 0 27 0000000000000000
IDLE 0 28 0000000000000000
IDLE 0 29 0000000000000000
IDLE 0 30 0000000000000000
IDLE 0 31 0000000000000000
IDLE 0 32 0000000000000000
Any ideas to solve this issue?
Thank you in advance
Edited by: albrotar on Apr 17, 2013 1:48 AM
Edited by: albrotar on Apr 17, 2013 1:49 AM
Edited by: albrotar on Apr 17, 2013 1:51 AM
Edited by: albrotar on Apr 17, 2013 1:52 AM
Edited by: albrotar on Apr 17, 2013 1:54 AM

I've found some errors in alert log file occurred at shutting down the database:
+...+
Control autobackup written to DISK device
handle '/orabck/rman/webfrbr/ora_cfc-3587726327-20130414-00'
Completed: CREATE UNDO TABLESPACE undotbs2 DATAFILE '/orabck/undo/undotbs02.dbf'
SIZE 500M reuse autoextend ON NEXT 5M maxsize 32767M
Sun Apr 14 15:46:43 2013
Successfully onlined Undo Tablespace 5.
Undo Tablespace 1 moved to Pending Switch-Out state.
*** active transactions found in undo tablespace 1 during switch-out.
Sun Apr 14 15:46:44 2013
ALTER SYSTEM SET undo_tablespace='UNDOTBS2' SCOPE=BOTH;
Sun Apr 14 16:11:42 2013
ALTER ROLLBACK SEGMENT "_SYSSMU7$" offLINE
Sun Apr 14 16:11:42 2013
Completed: ALTER ROLLBACK SEGMENT "_SYSSMU7$" offLINE
Sun Apr 14 16:12:36 2013
DROP TABLESPACE undotbs1 INCLUDING CONTENTS AND DATAFILES
Sun Apr 14 16:12:36 2013
+...+
Thread 1 advanced to log sequence 5107
Current log# 4 seq# 5107 mem# 0: /ora2/origlogs/webfrbr/redo04_m1.log
Current log# 4 seq# 5107 mem# 1: /ora3/mirrorlogs/webfrbr/redo04_m2.log
Sun Apr 14 19:00:28 2013
Stopping background process CJQ0
Sun Apr 14 19:00:29 2013
Stopping background process QMNC
Sun Apr 14 19:00:31 2013
Stopping background process MMNL
Sun Apr 14 19:00:32 2013
Stopping background process MMON
Sun Apr 14 19:00:34 2013
Shutting down instance (immediate)
License high water mark = 31
Sun Apr 14 19:00:34 2013
Stopping Job queue slave processes
Sun Apr 14 19:00:34 2013
Job queue slave processes stopped
All dispatchers and shared servers shutdown
Sun Apr 14 19:00:42 2013
ALTER DATABASE CLOSE NORMAL
Sun Apr 14 19:04:28 2013
+...+
Thread 1 advanced to log sequence 5118
Current log# 6 seq# 5118 mem# 0: /ora2/origlogs/webfrbr/redo06_m1.log
Current log# 6 seq# 5118 mem# 1: /ora3/mirrorlogs/webfrbr/redo06_m2.log
Sun Apr 14 20:11:21 2013
Errors in file /ora1/admin/webfrbr/bdump/webfrbr_smon_4629.trc:
+ORA-07445: exception encountered: core dump [_intel_fast_memcpy.A()+10] [SIGSEGV] [Invalid permissions for mapped object] [0x2B6B66003000] [] []+*
Sun Apr 14 20:11:21 2013
Errors in file /ora1/admin/webfrbr/bdump/webfrbr_smon_4629.trc:
ORA-00600: internal error code, arguments: [999], [0x107C14015], [], [], [], [], [], []*
+ORA-07445: exception encountered: core dump [_intel_fast_memcpy.A()+10] [SIGSEGV] [Invalid permissions for mapped object] [0x2B6B66003000] [] []+*
Sun Apr 14 20:11:22 2013
+...+
Sun Apr 14 20:11:48 2013
Errors in file /ora1/admin/webfrbr/bdump/webfrbr_pmon_4617.trc:
ORA-00474: SMON process terminated with error
Sun Apr 14 20:11:48 2013
+...+
The instance could start up, but after this, it is recovering undo and generating redo since 2 days

SQL Statement using Undo Tablespace

Hi
Is there a way to find out which SQL Statement is using the highest amount of Undo Tablespace ?

Query v$undostat.
Use column "MAXQUERYID" for identgifying long running queries.
Refer Metalink Note 262066.1 for undo information.
Regards
Sethu

TEST -- Active Undo Tablespace Drop

TEST
SUMMARY:-
When no active transactions are in UNDO tablespace, I can offline the undo datafile and subsequently drop the tablespace. No problems there.
Active Undo transactions combined with SHUTDOWN ABORT , I cannot open the database?
*****************SCREEN OUTPUT ************************
SQL>alter system set undo_tablespace='undotbs2' scope=spfile;
SQL> update mytst set table_name='jj';
1 row updated.
From another x-session I issued shutdown abort.
$mv undotbs02.dbf zz_undotbs02.dbf -- SImulate failure
SQL>ALTER DATABASE DATAFILE '/u02/app/oracle/oradata/HLCL/undotbs02.dbf' OFFLINE DROP ;
Database altered.
When i try to open the DB it gives
SQL> alter database open;
alter database open
ERROR at line 1:
ORA-01092: ORACLE instance terminated. Disconnection forced
I tried to trace the error:-
alter system set "_smu_debug_mode"=1 scope=spfile;
alter system set event = "10015 trace name context forever, level 10" scope=spfile;
No pertinent information in trace file is generated either. Any pointers.

ARC0: STARTING ARCH PROCESSES COMPLETE
ARC0: Becoming the 'no FAL' ARCH
ARC0: Becoming the 'no SRL' ARCH
ARC0: Becoming the heartbeat ARCH
ARC1 started with pid=17, OS id=4502
Thu Jun 22 17:58:28 2006
Errors in file /u02/app/oracle/admin/HLCL/udump/hlcl_ora_4498.trc:
ORA-00704: bootstrap process failure
ORA-00604: error occurred at recursive SQL level 2
ORA-00376: file 6 cannot be read at this time
ORA-01110: data file 6: '/u02/app/oracle/oradata/HLCL/undotbs02.dbf'
Thu Jun 22 17:58:28 2006
Error 704 happened during db open, shutting down database
USER: terminating instance due to error 704
Instance terminated by USER, pid = 4498
ORA-1092 signalled during: ALTER DATABASE OPEN...
/u02/app/oracle/admin/HLCL/udump/hlcl_ora_4498.trc:
Hash table buckets = 32768
Longest hash chain = 0
Average hash chain = 0/0 = 0.0
Max compares per lookup = 0
Avg compares per lookup = 0/0 = 0.0
tkcrrsarc: (WARN) Failed to find ARCH for message (message:0x1)
tkcrrpa: (WARN) Failed initial attempt to send ARCH message (message:0x1)
ORA-00704: bootstrap process failure
ORA-00604: error occurred at recursive SQL level 2
ORA-00376: file 6 cannot be read at this time
ORA-01110: data file 6: '/u02/app/oracle/oradata/HLCL/undotbs02.dbf'
Thanks for looking.

How to drop an undo tablespace which is in Pending Offline status

Dear All,
I changed my undo tablespace from undotbs1 to undonew in order to drop undotbs1.
But my undotbs1 is in pending offline state, how can i drop undotbs1
Thanks
Mahi

Check here
Managing the Undo Tablespace
Query V$TRANSACTION find out which transaction holding rollback segment on old undo tablespace. Commit or rollback it.
Or simply wait for a while patiently.
Quote "
The switch operation does not wait for transactions in the old undo tablespace to commit. If there are any pending transactions in the old undo tablespace, the old undo tablespace enters into a PENDING OFFLINE mode (status). In this mode, existing transactions can continue to execute, but undo records for new user transactions cannot be stored in this undo tablespace.
An undo tablespace can exist in this PENDING OFFLINE mode, even after the switch operation completes successfully. A PENDING OFFLINE undo tablespace cannot be used by another instance, nor can it be dropped. Eventually, after all active transactions have committed, the undo tablespace automatically goes from the PENDING OFFLINE mode to the OFFLINE mode.
"

Dropping Undo Tablespace

Hi,
I am running Oracle 9.2 on Solaris. I have Automatic undo management turned on and have a Undo tablespace by name UNDOTBS. It has a single datafile and has AUTOEXTEND feature turned on. My UNDO_RETENTION was set to 4 hours.
Presently, the size of UNDOTBS has grown to around 40G and has filled up the file system in which it resides. I need to clean up the file system. In order to do this, I followed the below procedure.
SQL> create undo tablespace UNDOTBS1 datafile '/u04/oradata/proddb/undo_00.dbf' size 1024M autoextend off;
SQ> alter system set undo_tablespace=undotbs1 scope=both;
SQL> alter system set undo_retention=3600 scope=both;
Now, i checked the alert log and it is offlining all the UNDO segments of the first undo tablespace UNDOTBS. It is taking time and has been more than 1.5 hours. I have a couple of questions here,
1. As i have issued "alter system undo_tablespace=undotbs1 scope=both", all the new transactions will use the new UNDOTBS1. No new transactions will be using the first undo tablespace UNDOTBS right?
2. Since, i have issued "alter system undo_retention=3600 scope=both", all the transactions in first undo tablespace UNDOTBS will be rolled back after 2 hours, no matter if it is commited or not. After this period, i am safe to drop the first undo tablespace using "drop tablespace UNDOTBS including contents and datafiles;". Did i get it right?
Any information will be of a great help.
THanks,
Harris.

Hi,
Thank you all for the replies. It has been two days since i switched the undo_tablespace to use the new tablespace(undotbs1) but my alert log is still being flooded with " Undo tablespace 1 moved to pending switch out state". I tried the following to see if there are any rows returne from the above query and it did 3 rows, showing some undo segments with the following output
SQL> select a.name, b.status from v$rollname a, v$rollstat b where a.name in (select segment_name from dba_segments where tablespace_name='UNDOTBS') and a.usn=b.usn;
Name Status
_SYSSMU15$      UNKNOWN
_SYSSMU33$      UNKNOWN
_SYSSMU9$        PENDING OFFLINE
I have seen gone through the metalink id: 341372.1 that speaks about this SWITCH-OUT state. How can i make sure what old transactions are still using the Undo segments in first undo tablespace and how can i go about killing them. Could anyone please let me know that i could use the following queries to find the correct sessions that are using the Old Undo tablespace.
SQL> select ADDR, XIDUSN,STATUS, START_TIME from v$transaction;
SQL> SELECT
a.usn,
a.name,
b.status,
c.tablespace_name,
d.addr,
e.sid,
e.serial#,
e.username,
e.program,
e.machine,
e.osuser
FROM
v$rollname a,
v$rollstat b,
dba_rollback_segs c,
v$transaction d,
v$session e
WHERE
a.usn=b.usn AND
a.name=c.segment_name AND
a.usn=d.xidusn AND
d.addr=e.taddr AND
b.status='PENDING OFFLINE';
Just wanted to make sure that the second query lists the PENDING OFFLINE segments of the first tablespace right?
This is a prod. box, so wanted to confirm with you guys before proceeding.
Thanks,
Harris.

How to Shrink UNDO Tablespace

Hello,
We had a UNDO Tablespace of 22Gb but it is using just 2GB. How to shrink undo tablespace. we are using clustered 3 node production database 10.2.0.4
Is there is way that we can shrink UNDO Tablespace or do i need to create a UNDO tablespace and assign the undo tablespace to DB and drop the old UNDO?
How to ensure that transactions are done and free to drop the old UNDO?
Is it something we need to restart all the three nodes as each node has its own UNDO Tablespace.
Need Help on this issue.
would appreciate your quick response.
Thanks

if i am in your place i will do the following:
<pre class="jive-pre">1-Query DBA_DATA_FILES to determine the name of the datafiles of the UNDO</pre>
2. Create a new UNDO tablespace.
<pre class="jive-pre">CREATE UNDO TABLESPACE undo_ts2 DATAFILE '/directory/undo_ts2_01.dbf' SIZE xxxM;</pre>
3. Modify the database parameter to use the new UNDO tablespace.
<pre class="jive-pre"> ALTER SYSTEM SET undo_tablespace=undo_ts2 SCOPE=BOTH; </pre>
4-The Drawback:
<pre class="jive-pre">New transactions will begin using the new undo tablespace. After some time passes (at least the number of seconds specified by the UNDO_RETENTION initialization parameter), you can drop the old UNDO tablespace. The downside to this approach is that for a short time period, your database will have two UNDO tablespaces</pre>
Regards
Mohamed

Undo tablespace growth

Hi ..
My undo tablespace is Growing rapidly from 1gb to 10 gb with an Hour.
Is there any ways to find out which operation Generates More Undo ..
Can i able to restrict it...

hi,
there is parameter that control the aging out of undo blocks that leverages size of UNDO tbs:
UNDO_RETENTION
You can guarantee that unexpired undo data is not overwritten even if it means that future operations that need to generate undo data will fail. This is done by specifying the RETENTION GUARANTEE clause for the undo tablespace when it is created by either the CREATE DATABASE or CREATE UNDO TABLESPACE statement. Alternatively, you can later specify this clause in an ALTER TABLESPACE statement.
more: UNDO RETENTION GUARANTEE

Find undo tablespace assignment in RAC

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