Fw: Lost ofall redo logs

[Tim Gorman]

Oh yeah!  How could I forget:  make darn sure that you are working with Oracle Support actively, step-by-step, if you are in a scenario which might call for the use of these parameters.  It would be *disastrous* to start down this road if unnecessary, and there are other quirks when using them that only OWS can diagnose and overcome...   ...need my coffee, NOW!   ----- Original Message ----- From: Tim Gorman To: [EMAIL PROTECTED] Sent: Thursday, September 19, 2002 7:03 AM Subject: Re: Lost ofall redo logs One correction...   The undocumented "_corrupted_rollback_segments" parameter does not take a TRUE/FALSE value setting.  It is another list of rollback segment names (similar to "rollback_segments" and "_offline_rollback_segments") which will be considered corrupted.  Roughly, the meaning of these undocumented parameters is (and I'm doing this from memory and pre-morning-coffee so those who know please correct as needed): rollback_segments List of rollback segment names on which to perform ALTER ROLLBACK SEGMENT ... ONLINE immediately after opening the database instance. _offline_rollback_segments List of rollback segments names to not scan during OPEN in order to mark transactions as "DEAD" (uncommitted) or "ROLLED BACK" (during instance recovery).  Also, these RBS will not be used for any new transactions and cannot be brought online.  Since these RBS do not have any DEAD transactions after OPEN, then SMON will not attempt rollback any txns behind the scenes.  If, while the instance is open, an entry in an ITL in a database block refers to one of these RBS, then the server process will attempt to read the transaction table in the RBS header and also attempt to read undo blocks in the RBS body in order to rollback the transaction or achieve a consistent read.  Please note that this is *dangerous* and that the instance can become "hung" through infinite loops and other nasty stuff while this is being performed.  In this event, the instance may have to be killed and the RBS involved may have to be listed in the "_corrupted_rollback_segment" parameter if there is any hope of using the database again... _corrupted_rollback_segments Another list of rollback segments to not scan during OPEN and not allow online after OPEN.  Transaction table is not scanned (as with "_offline_") during instance recovery and transactions within are not rolled back or marked DEAD, ever.  If, after the instance is open, an entry in an ITL in a database block refers to one of these RBS, then the server process will *not* attempt to reference the RBS in order to rollback the transaction or achieve a consistent read.  Instead, the changes from the transaction will be marked as "committed" as is. I'm sure that you can all see the danger in using these parameters.  Transactions that should be rolled back will not be.   With "_offline", the database will attempt to use info within the RBS but will never allow the RBS to be brought online for new transactions.  You use "_offline" if you think you can get away with salvaging the data in the RBS.   With "_corrupted", there is no hope, which is usually the situation if the header block of the RBS is corrupted.  In this case, the "after-image" data stored in the data segments (i.e. table, cluster, and index) are considered as "committed", since there is no way to tell if they really were or weren't.  The fact that the "after-images" may have been incomplete only adds to the fun and excitement...   As Arun had indicated (but not fully enough!), a database opened with either of these parameters really cannot be "trusted" for future use.  The firm recommendation is to use the database instance thus opened merely to salvage as much data as possible for import (one way or another) into a freshly-created new database.  Using these parameters will put the database on life-support for a short time only, hopefully long enough to extract its data.  It would be foolish to entrust new data to it ever again...   Hope this helps...   -Tim   ----- Original Message ----- From: "K Gopalakrishnan" <[EMAIL PROTECTED]> To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Thursday, September 19, 2002 12:58 AM Subject: RE: Lost ofall redo logs > Arun: > > You are right. The original poster *clearly* said > > LOST ALL REDO LOGS > NO BACKUP. > > In the above situation, you have to open the > databases using the some special tricks and > I don't think you need to go back and refer > BAckup and Recovery Manuals (You can not > find anything for this situation, that is > another story) > > Those parameters will bring up the database > if the database is cleanly shudowned (read: > Shutdown Normal/Immediate) and you will > have to do some more tricks to get the > database up if it is crashed (read: shutdown > ABORT). > > I don't think it is a bad advice.. > > YMMV > > KG > > > -----Original Message----- > Chakrapanirao > Sent: Wednesday, September 18, 2002 11:08 PM > To: Multiple recipients of list ORACLE-L > > > Well one I do want to make clear I have never tried to give bad advice to > people. > Since the user in his mail had said that he does not have a backup and does > not have any online redo logs can you please let me know how else can he > open the database, when he said he does not have a back it assumes that he > does not have a os backup and also the rman backup. > This might be the undocumented thing but this Is the only way it works > And this had happened in one our case and the only way we could open the > database is to force open the database in a corrupt mode take an export and > import back into the new database. > > If you still think I am trying to give a bad advice well sorry that I am > giving bad advices. > > > -----Original Message----- > Sent: Thursday, September 19, 2002 12:33 AM > To: Multiple recipients of list ORACLE-L > > Arun, since WHEN has been using undocumented parameters the normal way > of doing things, I think you need to go back and lookup backup/recovery > concepts. > > Feel free to read both user managed and RMAN backup recovery docs/scenarios. > > You are giving bad advice to people on the list who might be new. > > joe > > > Arun Chakrapanirao wrote: > > >The only way u can open your database is to add a parameter file > >as > > > >_allow_resetlogs_corruption=TRUE > > > >_corrupted_rollback_segments= TRUE > > > >_offline_rollback_segments=(the rollback segment names) > > > >activate the database and  then immediately take an export of the whole > >database. > >Create a new database and then import all the data to this new database. > > > > > >-----Original Message----- > >Sent: Wednesday, September 18, 2002 5:23 PM > >To: Multiple recipients of list ORACLE-L > > > >Nop, all redo logs gone away... > > > >----- Original Message ----- > >To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> > >Sent: Wednesday, September 18, 2002 5:43 PM > > > > > > > > > >>What about mirrored redo group members? > >> > >>Igor Neyman, OCP DBA > >>[EMAIL PROTECTED] > >> > >> > >> > >>----- Original Message ----- > >>To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> > >>Sent: Wednesday, September 18, 2002 4:30 PM > >> > >> > >>Hi people... > >> > >>What to do if I have LOST ALL REDO LOGS and i don4t have any backup? > >> > >>Thanks in advance! > >> > >>::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: > >>Gilberto Gampert                      Universidade de Passo Fundo > >>Administrador de Banco de Dados       Passo Fundo - RS - Bra5il > >>[EMAIL PROTECTED]                        http://www.upf.br > >>::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: > >> > >> > >>-- > >>Please see the official ORACLE-L FAQ: http://www.orafaq.com > >>-- > >>Author: Gilberto Gampert > >>  INET: [EMAIL PROTECTED] > >> > >>Fat City Network Services    -- 858-538-5051 http://www.fatcity.com > >>San Diego, California        -- Mailing list and web hosting services > >>--------------------------------------------------------------------- > >>To REMOVE yourself from this mailing list, send an E-Mail message > >>to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > >>the message BODY, include a line containing: UNSUB ORACLE-L > >>(or the name of mailing list you want to be removed from).  You may > >>also send the HELP command for other information (like subscribing). > >> > >>-- > >>Please see the official ORACLE-L FAQ: http://www.orafaq.com > >>-- > >>Author: Igor Neyman > >>  INET: [EMAIL PROTECTED] > >> > >>Fat City Network Services    -- 858-538-5051 http://www.fatcity.com > >>San Diego, California        -- Mailing list and web hosting services > >>--------------------------------------------------------------------- > >>To REMOVE yourself from this mailing list, send an E-Mail message > >>to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > >>the message BODY, include a line containing: UNSUB ORACLE-L > >>(or the name of mailing list you want to be removed from).  You may > >>also send the HELP command for other information (like subscribing). > >> > >> > >> > > > > > > > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Joe Testa >   INET: [EMAIL PROTECTED] > > Fat City Network Services    -- 858-538-5051 http://www.fatcity.com > San Diego, California        -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from).  You may > also send the HELP command for other information (like subscribing). > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Arun Chakrapanirao >   INET: [EMAIL PROTECTED] > > Fat City Network Services    -- 858-538-5051 http://www.fatcity.com > San Diego, California        -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from).  You may > also send the HELP command for other information (like subscribing). > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: K Gopalakrishnan >   INET: [EMAIL PROTECTED] > > Fat City Network Services    -- 858-538-5051 http://www.fatcity.com > San Diego, California        -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from).  You may > also send the HELP command for other information (like subscribing).