How to protect UNDO TABLESPACE in 9iR2

We can put REDO LOGs onto different disks by the means of multiplexing, so that even though one datafile is corrupted, the whole system would still be operational. But UNDO TABLESPACE doesn't provide such a mechanism. If the datafile of the active UNDO TABLESPACE is corrupted, it's dead.
I don't think a system would risk its availability on the single failure of the UNDO TABLESPACE. So there must be some tricks to circumvent this problem. Can anyone tell me that?
Thanks!

951368 wrote:
I am sorry... I should have been more clear...
The issue i have is : My primary is a 3 node RAC and i created the same 3 node physical standby, now we had a 4th node at our standby, standby allowed me to add all the required cluster parameteres like instance#,thread# for 4th node, but i was stopped at creating a undo tablespace for the 4th node. What is the procedure? do i need to create it at primary or is there a way i can directly create at standby?
ThanksHi,
So you have 3 nodes primary and wanted to add 4th node on standby?
Create the 4th undo tablespace in primary using
sql > create undo tablespace "undotbs4" datafile 'xxxxx' size xxxx;
The primary won't touch this undo as none of the instances should pointing to this new undo.
In the standby on 4th node define 'undo_tablespace' to undotbs4.
Cheers

Similar Messages

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

How to estimate undo tablespace size in 11g?

I found someone document said, use this sql to estimate undo tablespace:
select (UR*(UPS*DBS))+(DBS*24) as "bytes" from (select value as UR from v$parameter where name='undo_retention'),(select (sum(undoblks)/sum(((end_time-begin_time)*86400))) as UPS from v$undostat),(select value as DBS from v$parameter where name='db_block_size');
but in my 11g database, the "select value as UR from v$parameter where name='undo_retention'" is 0. so above sql is always get 196608(8192*24)
How to estimate undo tablespace size in 11g?
Thanks very much!

for undo segments size you should turn it to be autoextend on as well undo management set to be AUTO
i.e
undo_managment='AUTO'
for retention see that link
Ora-01555, snapshot too old: rollback segment number 2 with name "_SYSSMU1
BTW as hemant stated leave it to be auto which is good approach but make sure enough space on disk has been
dedicated for undo segments are allowed to grow to the size they need to be based on the requested undo_retention.
Khurram

How to recover undo tablespace in 9i

How can i recover undo tablespace 9i.Can any provide step by step recovery process

Doc ID 94114.1 on Metalink might be of interest to you

How to switch undo tablespace

Dear all,
I have created a new undo tablespace named undotbs2, How can i switch all the session use the undotbs2?
Many sessions are running and using the old undo tablespace named undotbs1.

user7244870 wrote:
CKPT wrote:
Sb has already mentioned links how to manage undo..
For more reference check this below links.
http://oracleflash.com/32/Change-or-switch-undo-tablespace-in-Oracle-database.html
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/undo.htm#BABGJBJH
I can't open the link.
http://oracleflash.com/32/Change-or-switch-undo-tablespace-in-Oracle-database.html
Is there a specific reason that you are not willing to read the official doc link?
http://download.oracle.com/docs/cd/E11882_01/server.112/e16508/logical.htm#CNCPT1079
Aman....

Undo Tablespace - newbie question

Q1. Is an Undo Tablespace mandatory in a database ? I thought the only mandatories were SYSTEM, SYSAUX and TEMP ?
Q2. What happens if you do not have an Undo Tablespace ?
Q2. How does an Undo Tablespace relate to Undo / Rollback Segments in a database ?

>
Just to give simple, one-liner replies though its all covered in the doc link given by Helios,
Q1. Is an Undo Tablespace mandatory in a database ? I thought the only mandatories were SYSTEM, SYSAUX and TEMP ?Yes, it is a mandatory tablespace loss of which would be requiring you to do a closed database recovery.
Q2. What happens if you do not have an Undo Tablespace ?The system tablespace's Undo segment would be used. But that's a bad idea and you should have one .
Q2. How does an Undo Tablespace relate to Undo / Rollback Segments in a database ?Because Undo segments are no where else but within the Undo tablespace only.
HTH
Aman....

Exclude undo tablespace in event

How to exclude undo tablespace from monotoring in grid control? If event is created to notify when tablespace is reached to 90% and wants to exlcude undo. Is it possible?

Edit the Undo tablespace and "Disable Threshold" on it.

How to rebuil undo and temp tbspc

Hi hussein/helios
Our apps undo and temp tablespaces got so big ( like 10Gb each) that it almost run out of space. Ho do i resync in back to 2Gb each.
Is there a system commnad like > alter tablespace undo resync?
Thanks a lot
msK

Hi,
Please refer tech note *262066.1 : How To Size UNDO Tablespace For Automatic Undo Management*
Hope helps.
Regards,
X A H E E R

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

How to exclude UNDO and temp tablespace using monitoring template

hi,
as per MOS note id 816920.1 undo and temp tablespace is excluded from monitoring starting version 11G onwards.It says that thresholds will need to be explicitly set if undo and temp needs to be monitored
we have grid 12C implemented now with monitoring templates which sets thresholds for all tablespaces. does it apply that thresholds to undo and temp too?? we are receiving alerts for undo and temp tablespaces and we wish to disable them. We have undo tablespaces with different names in many databases as per naming conventions for that line of business.
How can i exclude undo and temp tablespaces from monitoring using grid 12C monitoring templates. is there a way through templates where i can set thresholds of permanent tablespaces only???

In EM12c, go to the 'Enterprise' menu, then 'Job', then 'Library'. There should be an out-of-the-box job called "DISABLE TABLESPACE USED (%) ALERTS FOR UNDO AND TEMP TABLESPACES" that you can run against your database targets, and that job will disable database-generated alerts.
If a previous admin has set up EM12c-generated alerts for undo and temp, then yes, a monitoring template will take care of disabling them. Either remove those alerts from the existing monitoring template and apply them to your targets, or create a new monitoring template based on one database's current settings, remove those warning/critical thresholds for your undo and temp tablespaces, and apply it to your targets.

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.
"

2 Undo Tablespace both ONLINE, How to drop previous undo tbs

Hello Team,
Undo management=auto
After Cloning :-
To reclaim space i created another undo tablespace, but now both are online, but as per oracle as soon as you switch undo tablespace, previous undo TBS gets in Pending offline mode,offline mode, (So that transaction get finished)
But in my case Both UNDO Tablespaces are online
Previous Undo TBS1:- 600 GB
New UNDo Tb2s:- 100GB
Please suggest how to drop this online undo TBS1
TABLESPACE_NAME ONLINE_
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS1 ONLINE
APPS_UNDOTS2 ONLINE
APPS_UNDOTS2 ONLINE
TABLESPACE_NAME ONLINE_
APPS_UNDOTS2 ONLINE

Hi As per
select segment_name,owner,tablespace_name,status from dba_rollback_segs where tablespace_name like 'UNDOTBS1';
All Are offline for UNDOTBS1(Previous)
SEGMENT_NAME OWNER TABLESPACE_NAME STATUS
SYSSMU49861044602693$ PUBLIC APPS_UNDOTS1 OFFLINE
SYSSMU4893847838046$ PUBLIC APPS_UNDOTS1 OFFLINE
SYSSMU48682660477388$ PUBLIC APPS_UNDOTS1 OFFLINE
SYSSMU47753309457002$ PUBLIC APPS_UNDOTS1 OFFLINE
SYSSMU47131240212364$ PUBLIC APPS_UNDOTS1 OFFLINE
434 rows selected.

How to clear the undo tablespaces

I want to remove data from undo tablespace. How can I do that?

create new undo tablespace.
Change new as new undo tablespace.
Drop old undo tablespace.
If old undo tablespace will have any active undo segment it will not droped.
Cheers !!

UNDO Tablespace :: Who is using how much of it ?

Hallo,
I'd like to know who is using how many blocks of the undo-tablespace.
I know there's a view called v$undostat, but how to link this information to user, sql or session ?
Regards,
Mynz

Execute the following query to determine who is using a particular UNDO or Rollback Segment:
SQL> SELECT TO_CHAR(s.sid)||','||TO_CHAR(s.serial#) sid_serial,
2 NVL(s.username, 'None') orauser,
3 s.program,
4 r.name undoseg,
5 t.used_ublk * TO_NUMBER(x.value)/1024||'K' "Undo"
6 FROM sys.v_$rollname r,
7 sys.v_$session s,
8 sys.v_$transaction t,
9 sys.v_$parameter x
10 WHERE s.taddr = t.addr
11 AND r.usn = t.xidusn(+)
12 AND x.name = 'db_block_size';
SID_SERIAL ORAUSER PROGRAM UNDOSEG Undo

How the storage will be allocated on Undo tablespace made of datafiles?

I have a UNDO tablespace with two data files. Wherein one data file with Auto Extend as Yes and other as No.
In the case of multiple datafiles in UNDO tablespace,
1. Will the storage be allocated of same size on each datafile ?
2. What will be the case when the datafile with Auto Extent as NO reached it's max size?
3. Will the storage be allocated proportion to the datafile size in each file?

But when I use the following query, its not getting fired. Its taking "INDEX FULL SCAN"I would have thought that the later part of the above statement contradicts with the earlier part of the statement.
its not getting firedcontradicts this statement:
Its taking "INDEX FULL SCAN"Since the birth_dt is not the leading column of your index ...
Is it doing a INDEX FULL SCAN on the GPM_PERSONPROFILEDEMO_DOB2_IDX index?
if you have queries that involve profile_update_dt + birth_dt and some others that involve only birth_dt, then why not have the index in birth_dt + profile_update_dt instead?

How to protect UNDO TABLESPACE in 9iR2

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