Home » RDBMS Server » Backup & Recovery » bytes, blocks and extents of rollback segments are negative
bytes, blocks and extents of rollback segments are negative [message #507772] Tue, 17 May 2011 20:09 Go to next message
jim1944
Messages: 6
Registered: May 2011
Junior Member
Using Oracle 9.2 on Solaris.

I'm not a DBA but I am having to do some DBA work. Some DBAs I've talked to have no idea about this.

The issue is that the rollback segments for some of our database instances show negative numbers in dba_segments for bytes, blocks and extents. For those instances where this occurs, bytes is about -8.773E-09, blocks and extents are about -4.2 million. There is some minor variation in the numbers. This is the case for 3 out of 8 instances spread over two development labs. Each of the labs is similarly configured. In one lab, instances 1 and 2 have these weird values. In the other lab, instance four has these weird values.

All of the instances have undo_management=MANUAL.

What do these weird values mean? Is there a problem with the database? Are our databases subject to corruption as a result of these? Everything seems to be working but this bothers me.

I have tried dropping and recreating the rollback segments of one of the instances and, on recreation, they had the same weird values.

The statement used to create each of the rollback segments was the same except for <name>:
CREATE PUBLIC ROLLBACK SEGMENT <name>
TABLESPACE RBS
STORAGE (INITIAL 20 M
NEXT 20 M
OPTIMAL 100 M
MINEXTENTS 4
MAXEXTENTS UNLIMITED);

Thanks
Jim
Re: bytes, blocks and extents of rollback segments are negative [message #507775 is a reply to message #507772] Tue, 17 May 2011 20:28 Go to previous messageGo to next message
BlackSwan
Messages: 22783
Registered: January 2009
Senior Member
>Using Oracle 9.2 on Solaris.
Let me guess. this is a 32-bit system & software. Right?

>What do these weird values mean? Is there a problem with the database?
Then 2GB is the largest positive number that can exist in 32-bits.
Values between 2GB & 4GB are presented a negative numbers.
Re: bytes, blocks and extents of rollback segments are negative [message #507776 is a reply to message #507775] Tue, 17 May 2011 20:59 Go to previous messageGo to next message
jim1944
Messages: 6
Registered: May 2011
Junior Member
I think so. What if it is?
Re: bytes, blocks and extents of rollback segments are negative [message #507777 is a reply to message #507776] Tue, 17 May 2011 21:02 Go to previous messageGo to next message
jim1944
Messages: 6
Registered: May 2011
Junior Member
Oops. Why would there be any numbers greater than 2 or 4 GB immediately after creating the rollback segments and prior to any transactions against it.
Re: bytes, blocks and extents of rollback segments are negative [message #507779 is a reply to message #507776] Tue, 17 May 2011 21:03 Go to previous messageGo to next message
BlackSwan
Messages: 22783
Registered: January 2009
Senior Member
It would be helpful if you followed Posting Guidelines - http://www.orafaq.com/forum/t/88153/0/
Re: bytes, blocks and extents of rollback segments are negative [message #507780 is a reply to message #507779] Tue, 17 May 2011 21:15 Go to previous messageGo to next message
jim1944
Messages: 6
Registered: May 2011
Junior Member
I see two violations, perhaps three:
1. I did not specify Oracle version to 4 decimal places. I'm posting from home and do not have access to that info. I'll have to determine that work at work and post that info tomorrow.
2. I did not post the exact version of Solaris. Same issue as above.
3. The code statement is not properly indented. I actually did indent it but on posting it got reformatted somehow losing the indenting I did.

Is there anything I've missed and would any of the above make a difference?

Thanks
Jim
Re: bytes, blocks and extents of rollback segments are negative [message #507781 is a reply to message #507780] Tue, 17 May 2011 21:21 Go to previous messageGo to next message
BlackSwan
Messages: 22783
Registered: January 2009
Senior Member
>Is there anything I've missed and would any of the above make a difference?
How about posting actual SQL & results that you claim contain "weird" values?

I suggest your time would be better spent upgrading to a supported version of Oracle & joining the 21st Century;
rather than wasting time worrying about numbers over which you have little to no control.

Are the tablespaces DMT or LMT? post SQL & results

What is DB Block Size? post SQL & results
Re: bytes, blocks and extents of rollback segments are negative [message #507782 is a reply to message #507781] Tue, 17 May 2011 21:53 Go to previous messageGo to next message
jim1944
Messages: 6
Registered: May 2011
Junior Member
I'll get the SQL and results of the query from dba_segments that concern me and the additional information requested tomorrow.

I will not be able to post copy/pasted SQL and results because the work is being done in a DoD classified lab. The best I can do is write it down and retype it. I was hoping that the info I did provide would be enough to get some clue as to what is going on and whether or not there really is a problem. Obviously not. My apologies.

Upgrading to another version of Oracle is out of my control and not likely to happen anytime soon.

Thanks
Jim
Re: bytes, blocks and extents of rollback segments are negative [message #508007 is a reply to message #507782] Wed, 18 May 2011 20:59 Go to previous message
jim1944
Messages: 6
Registered: May 2011
Junior Member
OK here's the data:

Running Oracle 9i Enterprise Edition Release 9.2.0.7.0

prompt% cat /etc/release
Solaris 8 2/04 s28s_hw4wos_05a SPARC
Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
Assembled 08 January 2004


prompt% isainfo -kv
64-bit sparcv9 kernel modules


prompt% cd $ORACLE_HOME/bin
prompt% file oracl*
oracle: ELF 32-bit MSB executable SPARC Version 1, dynamically linked, not stripped
oracleO: ELF 32-bit MSB executable SPARC Version 1, dynamically linked, not stripped


SQL> select tablespace_name, extent_management, block_size from dba_tablespaces where tablespace_name='RBS';
TABLESPACE_NAME EXTENT_MAN BLOCK_SIZE
--------------- ---------- ----------
            RBS      LOCAL       2048

SQL>


SQL query of dba_segments attached.

Thanks
Jim
  • Attachment: segments.txt
    (Size: 2.07KB, Downloaded 85 times)
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