| Rollback segments too small [message #56544] |
Mon, 07 April 2003 16:32  |
Joe
Messages: 138
Registered: November 1999
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Senior Member |
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My rollback segments are too small. I have errors in my alert log that appear when attempting to run a database job. My question is what is the best way to size my rollback segments larger.
Create rollback segment new_rbs blah blah
and
drop rollback segment old_rbs.
Thank you in advance.
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| Re: Rollback segments too small [message #56545 is a reply to message #56544] |
Mon, 07 April 2003 23:35  |
Vikas Gupta
Messages: 115
Registered: February 2002
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Senior Member |
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You can do the following steps:
1. Create the Rollback Segment:
Create rollback segment rb17 storage
(initial 100k next 100k optimal 4m
minextents 20 maxextents 100 );
2. Bring the Rollback Segment Online:
Alter Rollback Segment rb17 online;
3. Alter the Parameter file to bring it Online
automatically whenever the instance starts.
Generally a thumb rule for rollback segments is:
No. of Users / No. Of RBS
< 16 / 4
16 - 32 / 8
> 32 / # of Users / 4.
Important Notes:
*Pctincrease will always be zero
*Initial & Next equal, this guarantees that the space
released could be used by another RBS.
*minextents = 20
*Always set Optimal.
*Make Sure all RBS same size.
Droping RBS:
1. First take it offline.
Alter Rollback Segment Rb1 Offline;
Note: Although all RBS becomes offline, you
wont be able to remove it, until all
transactions assigned to segment are
complete, check status in V$ROLLSTAT
it should be OFFLINE.
2. Drop it.
Drop Rollback Segment RB1;
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