Cacluation of undo tablespace size and retenion

How to calaculate the expected size of the undo tablespace and undo retention parameter from the exisitng data.

The easiest way to calculate undo requirementes is using the undo advisor, it is available in 10g and 9i. This is a graphical tool that lets you know the amount of required undo space according to your generated undo data.
Regards.

Similar Messages

UNDO Tablespace size

Hi,
We have a production database with size 120GB (DB Version 11.1.0.6), And our UNDO Tablespace size is 30GB.
For the past 4 days the UNDO tablespace utilization is more than 85%.
We have disabled the AUTOEXTEND for the UNDO Tablespace.
So the UNDO RETENTION is dynamically calculated by Oracle itself and the value now is
TUNED_UNDORETENTION
339183
Please suggest how to fix this issue.
Thanks !

Hi,
The UNDO Tablespace size is still increasing. We dont have flashnack enabled for our database.
The database is 11.1.0.6 Standard Edition.
TABLESPACE TOTAL_SIZE_IN_MB FREE_SPACE_IN_MB % FREE %USED
UNDOTBS1 32152 4440 14 86.19
USERS 123784 23120 19 81.32
SYSTEM 1536 465 30 69.73
SYSAUX 1024 449 44 56.15
GGS_DATA 2048 1388 68 32.23
We enabled AUTOEXTEND on for one of the datafiles in UNDO Tablespace.
NAME TYPE VALUE
undo_management string AUTO
undo_retention integer 9000
undo_tablespace string UNDOTBS1
select to_char(begin_time, 'DD-MON-RR HH24:MI') begin_time,
to_char(end_time, 'DD-MON-RR HH24:MI') end_time, tuned_undoretention
from v$undostat order by end_time;
BEGIN_TIME END_TIME TUNED_UNDORETENTION
23-DEC-11 18:15 23-DEC-11 18:25 375077
23-DEC-11 18:25 23-DEC-11 18:35 375678
23-DEC-11 18:35 23-DEC-11 18:45 376278
23-DEC-11 18:45 23-DEC-11 18:51 376578
Please let me know how can i reduce the space consumed by UNDO Tablespace.

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

Undo tablespace currupt and no clean backup

Hello,
We are facing critical problem with database. We have not any clean backup and database in no archive log mode. Suddenly database is shutdown and when we are trying to open database it is giving error:-
ORA-01172: recovery of thread 1 stuck at block 350230 of file 3
ORA-01151: use media recovery to recover block, restore backup if needed
File 3 is Undo file.
Is there any way to open database?
Thanks in advance and please reply us ASAP.

1) First, follow Howardjr recomendations and allways do a backup first.
2) Open a SR with Metalink to help with your problem
3) If you want to try something here are some options, but never skip the point 1 previously explained.
Well, you have two possible scenarios, one supported other unsupported.
This is an inconsistency issue..
Solution
============
*1]Supported Solution:*
Restore-Incomplete recovery the DB from backup or rebuild the DB using an export dump.
*2]Internal (Not-supported) Solution:*
Update undo$ to change the status$ = 1 (undo segment is dropped) for the corrupted undo segment.
Caution:
This is NOT a supported solution. Therefore ensure that a full database cold backup is taken bbefore doing this data-dictionary patching.
Steps to do the patching:
1) First ensure that a full database backup is taken.
2) Modify/add the following parameters in initSID.ora:
undo_management=manual
job_queue_processes =0
aq_tm_processes=0
systemtrig_enabled=false
3) Shutdown
4) Startup restrict pfile
5) set transaction use rollback segment system;
if set transaction above fails, then not to proceed further.
6) Update undo$ to change the status$ = 1 (undo segment is dropped) for
the corrupt undo segment.
update undo$ set status$ = 1
where us# = <'undo segment id'>
and ts#=<'tablespace id'>
and file#=<'file id'>
and block# = <'block id'>
and status$=2;
or
update undo$ set status$ = 1
where name = <'corrupt undo segment name'>
and status$=2;
This will update only 1 row. Rollback the update if more than 1 row is updated.
7) Commit;
8) Shutdown abort
9) Set back in init.ora parameters modified in Step 2.
Startup restrict
10) Drop the corrupt undo tablespace using command:
drop tablespace <corrupt undo tablespace name> including contents;
11) Create new undo tablespace.
In initSID.ora, set undo_management=auto, undo_tablespace=<'new undo tablespace name'>
Restart the instance.
12) Take a backup.
*Parameter offlinerollback_segments is not useful:*
Trying to drop the corrupt undo segment or the undo tablespace by setting parameters undo management=manual and offline_rollback_segments in initSID.ora will fails with error: ORA-00600 [ktssdrp1].
To see the information about the corrupt block use this query:
select us#, name, ts#, file#, block#,status$ from undo$
where (ts#, file#, block#) not in
(select ts#, file#, block# from seg$ where type# in (1,10)) and status$ > 1;I had the same problem some time ago, and the unsupported solution works great, but never try it without a full backup first.
Cheers,
Francisco Munoz Alvarez
http://oraclenz.wordpress.com
Edited by: F.Munoz Alvarez on Nov 30, 2012 11:03 AM

Query to check tablespace size and freespace

hi experts
i am using oracle 9i .
want ot check freespace and size of tablespace could u plz tell me the query
thanks
varun

add following for temp files -
select sum(bytes)/1024 kbytes_alloc, tablespace_name
from sys.dba_temp_files
group by tablespace_name
the new query will be
select b.tablespace_name, tbs_size SizeMb, a.free_space FreeMb
from
(select tablespace_name, round(sum(bytes)/1024/1024 ,2) as free_space
from dba_free_space group by tablespace_name) a,
(select tablespace_name, sum(bytes)/1024/1024 as tbs_size
from dba_data_files group by tablespace_name
UNION
select tablespace_name, sum(bytes)/1024/1024 tbs_size
from dba_temp_files
group by tablespace_name ) b
where a.tablespace_name(+)=b.tablespace_name;
cheers

Tablespace size and autoextend

hi,
if i am to create a tablespace with one datafile, i can size it to say 100M and set autoextend on. If it reaches 100M and then starts growing, does it make things run slower as it is constantly growing? would it be better if i had done some analysis and say sized it at 2000M? And if autoextend does make it slow down, how much does it slow it down by?
thanks

My personal preference is to create at 100m with autoextend on next 100m maxsize 16000m or so. But I don't think I'd do that for a tablespace that was going to be on the receiving end of thousands of concurrent inserts a minute in a heavy OLTP environment. For that sort of situation, I think I would prefer to create at 2000m autoextend on next 2000m maxsize 16000m.
Because the poor transaction that causes the autoextend obviously suffers from a nasty bout of waiting ...but no-one else will for quite a long while, thanks to that large 2GB jump in size. Meanwhile, my hard disk is not stuck there with an over-sized monster of a datafile that was over-sized by an overly-cautious DBA.
The thing being begged in your question, in other words, is "does it make things run slower as it is constantly growing".
If your files are truly CONSTANTLY growing, yes, you're in deep trouble and you will be suffering from severe slow-down. But if you choose an appropriate NEXT clause, you can have an OCCASIONAL growth of the file, sufficient for maybe a week or more's use, that only slows down one or two people for just a relatively short time.
Where you have heavy inserts going on, increase the NEXT clause to make the incidence of file growth keep at the 'not too often' level.
In the days of multi-hundred-gig disks, I would think that any DBA sitting there still trying to predict the future as far as disk space usage is concerned is just wasting his time. As jgarry put it, there are lots of other things more deserving of your attention. There's no pressing need to ration out carefully something (ie, space) which is abundant, in other words.

FLASHBACK OFF FOR UNDO TABLESPACE????

Hi all
As my Undo tablespace growing evryday 2 GB & NOW it reached 19,
Database size is 6GB only
using Oracle 10g Release 2 without patch Set (release 1002000100) on Hp-Unix OS
Can i use the Undo tablespace with FLASHBACK OFF option?
what are the Consequences for Turning off the FLASHBACK,
Can we use this type of Undo tablespace with Flashback OFF???
CREATE UNDO TABLESPACE UNDOTBS03 DATAFILE
'/app/oracle/product/oradata/prod/undotbs03.dbf' SIZE 1000M AUTOEXTEND OFF
ONLINE
RETENTION NOGUARANTEE
BLOCKSIZE 8K
FLASHBACK OFF;
THANKS ALOT

Oracle Flashback Database: feature is similar to conventional point-in-time recovery in its results, allowing you to return a database to its state at a time in the recent past. It is, however, much faster than point-in-time recovery, because it does not require restoration of datafiles from a backup and it requires application of fewer changes from the archived redo logs.
UNDO Tablespace: Oracle db save the old value when a process change data in undo tablespace.
I think that you can change de default UNDO tablespace as NO AUTOEXTEND, and
Configure
SET UNDO_MANAGEMENT=AUTO
SET UNDO_RETENTION= ( second need for logger transaction )
UNDO_RETENTION specifies (in seconds) the low threshold value of undo retention. For AUTOEXTEND undo tablespaces, the system retains undo for at least the time specified in this parameter, and automatically tunes the undo retention period to satisfy the undo requirements of the queries.
For fixed- size undo tablespaces, the system automatically tunes for the maximum possible undo retention period, based on undo tablespace size and usage history, and ignores UNDO_RETENTION unless retention guarantee is enabled.

Relation between undo_retention and undo tablepsace size

Hello,i am on 10.2.0.3.
Can someone please clear this things a little bit.
Let's say that i have one SQL that is doing inserts or updates and this have execution time of 30 minutes,
and my undo_retention parameter is set to 20mins, undo_management=auto, and undo tablespace of 30GB of which is curently taken only 1GB,
will this insert fail with ora-1555 snapshot too old or not ?
Is undo_retention the only thing that determines how long query can be run or i can focus on undo tablespace size also if there is enough space in it ?

No, the DML activity load on the system during any given period of time is the most important factor in how your undo is handled. How you define your undo tablespace in your choice of building it using extendable data files or with a fixed size (my recommendation) also comes into play.
If you use a fixed size undo tablespace Oracle will attempt to use it all before overlaying data.
The DBA Administration manual has a decent discussion of undo tablespace managment and sizing considerations in the chapter on managing undo.
HTH -- Mark D Powell --

Tablespace used and free space size in 9i

Hi,
How to find the tablespace used space and tablespace free space in 9i.
Normally i uses below query in 10g and 11g, but this query not working in 9i. Please help the query for 9i....
SELECT /* + RULE */ df.tablespace_name "Tablespace",
df.bytes / (1024 * 1024) "Size (MB)",
SUM(fs.bytes) / (1024 * 1024) "Free (MB)",
Nvl(Round(SUM(fs.bytes) * 100 / df.bytes),1) "% Free",
Round((df.bytes - SUM(fs.bytes)) * 100 / df.bytes) "% Used"
FROM dba_free_space fs,
(SELECT tablespace_name,SUM(bytes) bytes
FROM dba_data_files
GROUP BY tablespace_name) df
WHERE fs.tablespace_name (+) = df.tablespace_name
GROUP BY df.tablespace_name,df.bytes
UNION ALL
SELECT /* + RULE */ df.tablespace_name tspace,
fs.bytes / (1024 * 1024),
SUM(df.bytes_free) / (1024 * 1024),
Nvl(Round((SUM(fs.bytes) - df.bytes_used) * 100 / fs.bytes), 1),
Round((SUM(fs.bytes) - df.bytes_free) * 100 / fs.bytes)
FROM dba_temp_files fs,
(SELECT tablespace_name,bytes_free,bytes_used
FROM v$temp_space_header
GROUP BY tablespace_name,bytes_free,bytes_used) df
WHERE fs.tablespace_name (+) = df.tablespace_name
GROUP BY df.tablespace_name,fs.bytes,df.bytes_free,df.bytes_used
ORDER BY 4 DESC;
Regards,
Pravin

hi,
try this
/* TOTAL, FREE AND USED SPACE IN TABLESPACES */ SET LINESIZE 100 COLUMN TABLESPACE FORMAT A15 select t.tablespace, t.totalspace as " Totalspace(MB)", round((t.totalspace-fs.freespace),2) as "Used Space(MB)", fs.freespace as "Freespace(MB)", round(((t.totalspace-fs.freespace)/t.totalspace)*100,2) as "% Used", round((fs.freespace/t.totalspace)*100,2) as "% Free" from (select round(sum(d.bytes)/(1024*1024)) as totalspace, d.tablespace_name tablespace from dba_data_files d group by d.tablespace_name) t, (select round(sum(f.bytes)/(1024*1024)) as freespace, f.tablespace_name tablespace from dba_free_space f group by f.tablespace_name) fs where t.tablespace=fs.tablespace order by t.tablespace;
and you can have a look this thred. it will be hellp you
query to check tablespace size and freespace
regards,

Differance between Rollback Segements and Undo Tablespace/segments

Hi everyone.
I have some confusion that how Rollback Segements and Undo Tablespace/segments and different? Functionally they seem to be the same but why then Oracle recommends not using Rollback segments?...please explain. Kindly post any links useful in this regard.
Thanks,
Mukesh

1.when does the changed data written to the undo tablespace?It never gets moved to the undo tablespace.
The ORIGINAL data gets moved to the rollback/undo. Oracle assumes that most of the time the transaction is going to commit, so the change is made to the real block (in memory). At that time, enough information to roll back that change is written into the rollback segment.
2.which process writes the changed data to the undo tbs?The server process. The one to which the user connects. The one the user gets by contascting the listener.
3.What are the identifiactions which is used to undo the changes made(like SCN) ? plz...AFAIK, Transaction Id is the only thing used. SCN, a redo log construct, may be used to recreate the transaction ID in the rollback.

ORA-30036: unable to extend segment by 8 in undo tablespace 'UNDO'

Hello,
I have an OWB Mapping (which translates into a MERGE query) that often fails with the above error. I wanted to have more information on UNDO. What uses most UNDO?
Thanks.

Dear mugunthan,
One little, tiny correction that i want to make. I can get what you wanted to say when you said "increase the tablespace". Normally we are not increasing the size of the tablespace, we are increasing the size of the "datafiles" in that tablespace. That is tricky and how words can change everything i know but just for the information :)
I think the OP's undo tablespace size is 100% full and the auto extensible ability is disabled. He needs to either increase the size of the datafile in the undo tablespace slightly more or enable the auto extensible of one more datafiles (if exists) to a particular new and more bigger size.
Regards.
Ogan

Tuning UNDO tablespace - 10g

Hi,
Currently my undo tablespace is 1GB (data file not set to autoextensible due to filesystem space constraint) and undo retention is 900 seconds.
I'm facing alot of snapshot too old errors.
I'm going to increase/tune tablespace size and also undo retention period. from the below query from gv$undostat, shud i set the maximun retention period of undo to the max query length? or only to the max query length there the ora-01555 error happens? how abt the tablespace sizing, how can i estimate.. please advise experts.
Tuned Undo # Unexpired # Expired ORA-1555 Out-Of-space Max Query
INST_ID BEGIN_TIME Retention Stolen Reused Error Error Length
1 07/21/2008 11:12 49564 0 438 0 0 1421
1 07/21/2008 11:22 2086 173 497 0 5 2022
1 07/21/2008 11:32 2602 64 65 0 3 1768
1 07/21/2008 11:42 3118 0 0 0 0 1847
1 07/21/2008 11:52 3632 3 12 0 0 385
1 07/21/2008 12:02 4146 2 17 0 0 572
Tuned Undo # Unexpired # Expired ORA-1555 Out-Of-space Max Query
INST_ID BEGIN_TIME Retention Stolen Reused Error Error Length
1 07/21/2008 12:12 4659 57 60 0 0 32
1 07/21/2008 12:22 5175 47 53 0 0 12
1 07/21/2008 12:32 5690 0 43 0 0 105
1 07/21/2008 12:42 6203 0 116 0 0 488
1 07/21/2008 12:52 6719 0 116 0 0 1088
1 07/21/2008 13:02 7231 0 330 0 0 1687
1 07/21/2008 13:12 7743 0 229 0 0 2290
1 07/21/2008 13:22 8248 13 393 0 0 666
1 07/21/2008 13:32 8713 278 420 0 0 459
1 07/21/2008 13:42 9180 170 288 1 0 1058
1 07/21/2008 13:52 9650 286 335 2 0 1657
1 07/21/2008 14:02 10141 51 273 2 0 733
1 07/21/2008 14:12 10610 85 584 0 0 1389
1 07/21/2008 14:22 10963 89 283 2 0 1716
1 07/21/2008 14:32 12022 32 264 0 0 1598
1 07/21/2008 14:42 10783 0 158 0 0 2918
1 07/21/2008 14:52 11902 0 134 1 0 3519
1 07/21/2008 15:02 13283 34 658 0 0 4121
1 07/21/2008 15:12 12044 0 322 0 0 4722
1 07/21/2008 15:22 2932 5 208 0 0 5322
1 07/21/2008 15:32 3497 45 398 0 0 6200
Tuned Undo # Unexpired # Expired ORA-1555 Out-Of-space Max Query
INST_ID BEGIN_TIME Retention Stolen Reused Error Error Length
1 07/21/2008 15:42 4071 8 489 0 0 6800
1 07/21/2008 15:52 4637 386 494 0 5 7402
1 07/21/2008 16:02 5209 200 812 0 1 7727
1 07/21/2008 16:12 5775 319 568 1 7 1138
1 07/21/2008 16:22 6345 3 1220 0 0 1740
1 07/21/2008 16:32 6858 0 5575 0 0 98
1 07/21/2008 16:42 7420 4 777 0 0 606
1 07/21/2008 16:52 7952 32 1344 0 0 604
1 07/21/2008 17:02 8293 0 6 0 0 43
576 rows selected.

Snapshot too old error's most useful solution is to raise the undo tablespace's size. I would raise it anyway, but i think you need to report your manager that you need to upgrade the system, indeed 900 seconds undo retention is not enough to your database.
Simple logic, growing database, growing sql queries, decreasing or steady hardware and sizes? IMPOSSIBLE.

How to see tablespace size in data dictionary

How can I see the tablespace size, and used tablespace size in data dictionary view?
it is not in dba_tablespaces, and v$tablespace
Thanks.

I like this little piece of code of mine:
SQL> SELECT
2          TABLESPACE_NAME,
3          RPAD(RPAD('|',100-PCT_FREE,'X'),100) || '|' USED
4 FROM (SELECT TABLESPACE_NAME,
5    100 -
6      ROUND(100 -(SUM(BYTES)/1024/1024/1024)*100/
7                  (SELECT SUM(BYTES)/1024/1024/1024
8                   FROM DBA_DATA_FILES DF
9                   WHERE DF.TABLESPACE_NAME=FS.TABLESPACE_NAME),2
10            ) PCT_FREE,
11    ROUND(SUM(BYTES)/1024/1024/1024,2) GIBFREE
12 FROM DBA_FREE_SPACE FS
13 GROUP BY TABLESPACE_NAME) TABLESPACE_SPACE
14* ORDER BY TABLESPACE_NAME;
TABLESPACE_NAME                USED
ARCHDATA                       |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX      |
DATBIGGX                       |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                  |
DATGX                          |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                                                      |
DATLOWGX                       |XXXXXXXXXXXXXXXXXXXXXX                                                                             |
IDXBIGGX                       |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                 |
IDXLGX                         |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                |
IDXGX                          |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX          |
LOGMNRTS                       |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                                           |
SYSTEM                         |XXXXXXXXXXXXXXXX                                                                                   |
TOOLS                          |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                                                   |
UNDOGX                         |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                                         |Yoann.

Tablespace Size

hi,
I am using Oracle 8i. From DBA studio i see that the space assigned to data files is 98.5% full. will it affect performance ?? Ther is very few much space avaiable in the drive. Data file size is around 12 GB auto extend is 50% and free space is 3 GB.
Please suggest...

If the data blocks are not cached in your shared pool , then it will read data blocks from the datafiles and this will leads to some performance issuies.Kuljit already pointed out from your answer that data blocks resides in buffer cache not in the shared pool.
My point is, sometimes, physical reads are better than logical reads. To tune a query, one must concentrate to reduce logical reads. (buffer gets).
Regarding tablespace size and performance problem, as long as there is free space is avaialble then no problems.
If the tablespace is 100% used and its data files are autoextend enabled, then, when oracle needs space to insert datafile and tbs is 100% and its datafile are autoextend, then, oracle has to allocate new exten to keep the data. In this scinario, there might be a slight issue.
If the tbs is locally managed, it will not be that must.
Moreover, if the database is OLTP with heavey transactions, then, its always better to have good amount of free space i the tablespaces.
Jaffar

Undo retention and tablespace size

Situation:
Oracle 9.2.0.1 configured with undo_retention=10800 but with a 2GB size limit for the
undo tablespace with no autoextend.
As far as i know, with 10800 the undo tablespace could grown to around 10GB
but i'm not sure tho. I REALLY need to know if this is clearly a wrong setup (imho it
is) or could be an acceptable situation in some scenarios.
Thanks heap in advance.

Oracle 9.2.0.1 configured with undo_retention=108003 Hours? This is realy huge undo retention time.
with a 2GB size limit for the undo tablespace with no autoextend.You probably mean datafile not tablespace.
You don't need resize existing datafile you could just add another datafile to undo tablespace.

Cacluation of undo tablespace size and retenion

Similar Messages

Maybe you are looking for