Redo log data

How to find the actual data redolog contains? My redo log is of 1 GB of each group. We have moved the redolog to newer disk, so i want to know the actual size of redolog, how much data it carries and how we can analyze/tune redolog to increase performance.
Thanks

Hi,
>>How to find the actual data redolog contains?
I think that you can take a look at the "actual_redo_blks" column in v$instance_recovery dynamic performance view in order to see the current number of redo blocks required to be read in case of recovery.
>>how much data it carries and how we can analyze/tune redolog to increase performance.
Oracle 10g has introduced a redo logfile sizing advisor that will recommend a size for the redo logs that limit excessive log switches, incomplete and excessive checkpoints, log archiving issues, DBWR performance and excessive disk I/O. So, you can obtain redo sizing advice on the redo log groups page of Oracle Enterprise Manager Database Control.
Cheers

Similar Messages

What's the point of redo logs?

Why does Oracle bother writing everything to redo logs? If it's going to write data changes to the disk, why not just write them once to the data files and be done with it? What's the point of doing it twice? And if it's a redundancy thing, why not mirror the data disks?

Hemant K Chitale wrote:
How would you backup a database while it is in use ? You can't lock all the datafiles to prevent writes to them. Yet, transactions may be updating different blocks in different datafiles even as the backup is in progress. Say your backup starts with datafile 1 (or even datafiles 1,2,3,4 in parallel) at time t0. By time t5, it has copied 20% of the datafile to tape or alternate disk backup location. Along comes a transaction that updates the 100th block (somewhere within the 10-11% range) of datafile 1 and also the 60th block of datafile 5. Meanwhile, the backup continues running, already having taken a prior image of the 100th block and not being aware that the block has been changed. At time t25 it completes datafile 1 (or datafiles 1,2,3,4) and starts backing up datafile 5. Now, when it copies the 60th block of datafile 5, it (the backup utility) doesn't know that this block is inconsistent with the backup image of the 100th block of datafile 1.
Instead of 1 transaction imagine 100 or 1000 transactions occurring while the backup is running.
Surely, Oracle must be able to regenerate a consistent image of the whole database when it is restored ?
That is what the Redo stream provides. The Redo stream is written to Archivelogs so that it can be backed up -- no Archivelog file is "in flux" (particularly if you use RMAN to backup the Archivelogs as well !).
Had Oracle been merely writing to the datafiles alone, without a Redo stream, there is no way it could recreate a consistent database -- whether after Crash Recovery OR after Media Recovery.Interesting point about how redo logs facilitate backups. So what you're saying is that the redo logs help keep the data in the actual data files in a consistent state by only writing full transactions to them at a time. Presumably Oracle will either write out the redo log data to the data files before a backup or will at least prevent the redo logs from writing to the data files during a backup. I always wondered how databases got around that problem of keeping the system available for writing during a backup. I wonder how SQL Server does it.
Hemant K Chitale wrote:
Now, approach this from another angle. A database consists of 10 or 100 or 500 datafiles. You have 10 or 100 or 1000 sessions issuing COMMITs to complete their transactions, which could be of 1 row or 100 rows or 1million rows, each transaction of a different size. Should the 1000 sessions be forced to wait while Oracle writes all those updated blocks to disk in different datafiles -- how many blocks can it write in "an instant" ?
But what if Oracle manages to write much less information -- the bare minimum (called "change vectors") to re-play every transaction to a single file serially ? That would be much faster. Imagine writing to 500 datafiles concurrently, having to open the file, progess to the required block address and update the block, for each block changed in each file VERSUS writing much lesser information serially to a single file -- if the file is full, switch to another file, but keep writing serially.As to your second point, I don't really have a good enough understanding about the format of redo logs vs. the data files to follow you totally. Are you saying that it takes more time to write to the data files because you have to find the proper place in the B-Tree before you can write to it? And that doing that is slower than just opening the redo log and always appending new information to the very end? Maybe so, but it seems like all transactions having to write to a single redo log in serial would slow things down since there would be a ton of contention for one file. Whereas with the data files, you could potentially have several transactions writing to different files simultaneously (provided you hardware would support doing that). And it seems to me like a change vector would contain a lot more information than a field value, but, like I said, I'm not really familiar with the format.

Where RFS exactly write redo data ? ( archived redo log or standby redo log ) ?

Good Morning to all ;
I am getting bit confused from oracle official link . REF_LINK : Log Apply Services
Redo data transmitted from the primary database is received by the RFS on the standby system ,
where the RFS process writes the redo data to either archived redo log files or standby redo log files.
In standby site , does rfs write redo data in any one file or both ?
Thanks in advance ..

Hi GTS,
GTS (DBA) wrote:
Primary & standby log file size should be same - this is okay.
1) what are trying to disclose about largest & smallest here ? - You are confusing.
Read: http://docs.oracle.com/cd/E11882_01/server.112/e25608/log_transport.htm#SBYDB4752
"Each standby redo log file must be at least as large as the largest redo log file in the redo log of the redo source database. For administrative ease, Oracle recommends that all redo log files in the redo log at the redo source database and the standby redo log at a redo transport destination be of the same size."
GTS (DBA) wrote:
2) what abt group members ? should be same as primary or need to add some members additionally. ?
Data Guard best practice for performance, is to create one member per each group in standby DB. on standby DB, one member per group is reasonable enough. why? to avoid write penalty; writing to more than one log files at the standby DB.
SCENARIO 1: if in your source primary DB you have 2 log member per group, in standby DB you can have 1 member per group, additionally create an extra group.
primary
standby
Member per group
2
1
Number of log group
4
5
SCENARIO 2: you can also have this scenario 2 but i will not encourage it
primary
standby
Member per group
2
2
Number of log group
4
5
GTS (DBA) wrote:
All standby redo logs of the correct size have not yet been archived.
- at this situation , can we force on standby site ? any possibilities ?
you can not force it , just size your standby redo files correctly and make sure you don not have network failure that will cause redo gap.
hope there is clarity now
Tobi

Data Guard - Redo log files

Hi....
I have done data guard .......every thing is fine.......archives are bring transferred to standby..........
Also, during configuration, I had created standby redolog groups 4,5,6 and copied to standby.....
But in real time apply.......the standby is not using standby redolog groups 4,5,6........when i am query v$log it is showing group 1,2,3.
Actually, its should use standby redo log for maximum availability.
Please help....
Thanks in advance.

There was a similar question here just a few days ago:
Data Guard - redo log files

Tuning of Redo logs in data warehouses (dwh)

Hi everybody,
I'm looking for some guidance to configure redo logs in data warehouse environments.
Of course we are running in noarchive log mode and use direct path inserts (nologging) whereever possible.
Nevertheless every etl process (one process per day) produces 150 GB of redo logs. That seems quite a lot compared to the overall data volume (1 TB tables + indexes).
Actually im not sure if there is a tuning problem, but because of the large amount of redo I'm interested in examining it.
Here are the facts:
- Oracle 10g, 32 GB RAM
- 6 GB SGA, 20 GB PGA
- 5 log groups each with 1 Gb log file
- 4 MB Log buffer
- every day ca 150 logswitches (with peaks: some logswitches after 10 seconds)
- some sysstat metrics after one etl load:
Select name, to_char(value, '9G999G999G999G999G999G999') from v$sysstat Where name like 'redo %';
"NAME" "TO_CHAR(VALUE,'9G999G999G999G999G999G999')"
"redo synch writes" " 300.636"
"redo synch time" " 61.421"
"redo blocks read for recovery"" 0"
"redo entries" " 327.090.445"
"redo size" " 159.588.263.420"
"redo buffer allocation retries"" 95.901"
"redo wastage" " 212.996.316"
"redo writer latching time" " 1.101"
"redo writes" " 807.594"
"redo blocks written" " 321.102.116"
"redo write time" " 183.010"
"redo log space requests" " 10.903"
"redo log space wait time" " 28.501"
"redo log switch interrupts" " 0"
"redo ordering marks" " 2.253.328"
"redo subscn max counts" " 4.685.754"
So the questions:
Does anybody can see tuning needs? Should the Redo logs be increased or incremented? What about placing redo logs on Solid state disks?
kind regards,
Mirko

user5341252 wrote:
I'm looking for some guidance to configure redo logs in data warehouse environments.
Of course we are running in noarchive log mode and use direct path inserts (nologging) whereever possible.Why "of course" ? What's your recovery strategy if you wreck the database ?
Nevertheless every etl process (one process per day) produces 150 GB of redo logs. That seems quite a lot compared to the overall data volume (1 TB tables + indexes).This may be an indication that you need to do something to reduce index maintenance during data loading
>
Actually im not sure if there is a tuning problem, but because of the large amount of redo I'm interested in examining it.
For a quick check you might be better off running statspack (or AWR) snapshots across the start and end of batch to get an idea of what work goes on and where the most time goes. A better strategy would be to examine specific jobs in detail, though).
"redo synch time" " 61.421"
"redo log space wait time" " 28.501" Rough guideline - if the redo is slowing you down, then you've lost less than 15 minutes across the board to the log writer. Given the number of processes loading and the elapsed time to load, is this significant ?
"redo buffer allocation retries"" 95.901" This figure tells us how OFTEN we couldn't get space in the log buffer - but not how much time we lost as a result. We also need to see your 'log buffer space' wait time.
Does anybody can see tuning needs? Should the Redo logs be increased or incremented? What about placing redo logs on Solid state disks?Based on the information you've given so far, I don't think anyone should be giving you concrete recommendations on what to do; only suggestions on where to look or what to tell us.
Regards
Jonathan Lewis

Windows Modified date for online redo logs

I am doing a full database backup (oracle 10g) weekly and incremental backups nightly. The database is running in archivelog mode and I am multiplexing the online redo logs. However, when I look in windows the modified date for all Redo logs is displayed at the time the database was started up (Sunday night)... datafiles, controlfiles etc... show the latest modified date correctly.
Is this normal that the modified date is not updating on redo logs or do I need to do something else to ensure my online redo is operating correctly.
Any help would be appreciated.

Redo3 was the setting before the switch... redo1 is now the current log. As regards the alert log... what file should I check... there is nothing showing in OEM.
MEMBER
GROUP# STATUS
D:\ORACLE\PRODUCT\ORADATA\WATLI1\REDO03.LOG
3 ACTIVE
D:\ORACLE\PRODUCT\ORADATA\WATLI1\REDO02.LOG
2 INACTIVE
D:\ORACLE\PRODUCT\ORADATA\WATLI1\REDO01.LOG
1 CURRENT
MEMBER
GROUP# STATUS
E:\BACKUP\ONLINELOGS\REDO01_A.LOG
1 CURRENT
E:\BACKUP\ONLINELOGS\REDO02_A.LOG
2 INACTIVE
E:\BACKUP\ONLINELOGS\REDO03_A.LOG
3 ACTIVE

How could I find specified date of REDO log and archive REDO log ?

we use Oracle11gr2 on win2008R2.
1
How could I find specified date of REDO log(2013/10/17,etc) and archive REDO log ?
2
What is the format of archive REDO log.? (zipped file ?)

user12075536123 wrote:
1)
select * from v$archived_log;
select * from v$log_history;
but there is a possibility there is no old data
below contains no filename column
SQL> desc v$log_history
Name                                      Null?    Type
RECID                                              NUMBER
STAMP                                              NUMBER
THREAD#                                            NUMBER
SEQUENCE#                                          NUMBER
FIRST_CHANGE#                                      NUMBER
FIRST_TIME                                         DATE
NEXT_CHANGE#                                       NUMBER
RESETLOGS_CHANGE#                                  NUMBER
RESETLOGS_TIME                                     DATE
there is NO data when archive mode is disabled

Redo Log Last modified date

Hi All,
Couple of day's back we have set Hot back up mode for 11g database server from cold back up,
after this reado log's last modified date is not getting updated and redolog last modified date is get's updated only when we restart the database,
There is no error message in the alert log and data base running normally without any issues,
can you please advise me why redo logs LastModified date is not getting updated.
Thanks
sankar

user12994238 wrote:
Hi All,
Couple of day's back we have set Hot back up mode for 11g database server from cold back up,
after this reado log's last modified date is not getting updated and redolog last modified date is get's updated only when we restart the database,
There is no error message in the alert log and data base running normally without any issues,
can you please advise me why redo logs LastModified date is not getting updated.
Thanks
sankarcould it be that the timestamp is not updated until such time as the file is closed? That would be easy enough to observe/test.

Unable to ship Redo logs to standby DB (Oracle Data Gaurd)

Hi all,
We have configured Oracle Data Gaurd between our Production (NPP) & Standby (NPP_DR).
The configuration is complete however, the production is unable to ship redo logs to standby DB.
We keep getting the error "PING[ARC0]: Heartbeat failed to connect to standby 'NPP_DR'. Error is 12154." in Primary DB
Primary & DR are on different boxes.
Please see the logs below in the production alert log file & npp_arc0_18944.trc trace files:
npp_arc0_18944.trc :*
2011-01-19 09:17:38.007 62692 kcrr.c
Error 12154 received logging on to the standby
Error 12154 connecting to destination LOG_ARCHIVE_DEST_2 standby host 'NPP_DR'
Error 12154 attaching to destination LOG_ARCHIVE_DEST_2 standby host 'NPP_DR'
2011-01-19 09:17:38.007 62692 kcrr.c
PING[ARC0]: Heartbeat failed to connect to standby 'NPP_DR'. Error is 12154.
2011-01-19 09:17:38.007 60970 kcrr.c
kcrrfail: dest:2 err:12154 force:0 blast:1
2011-01-19 09:22:38.863
Redo shipping client performing standby login
OCIServerAttach failed -1
.. Detailed OCI error val is 12154 and errmsg is 'ORA-12154: TNS:could not resolve the connect identifier specified
alert log file on Primary*
Error 12154 received logging on to the standby
Wed Jan 19 09:02:35 2011
Error 12154 received logging on to the standby
Wed Jan 19 09:07:36 2011
Error 12154 received logging on to the standby
Wed Jan 19 09:12:37 2011
Error 12154 received logging on to the standby
Wed Jan 19 09:13:10 2011
Incremental checkpoint up to RBA [0x2cc.2fe0.0], current log tail at RBA [0x2cc.2fe9.0]
Wed Jan 19 09:17:38 2011
Error 12154 received logging on to the standby
Wed Jan 19 09:22:38 2011
Error 12154 received logging on to the standby
Wed Jan 19 09:27:39 2011
Error 12154 received logging on to the standby
However, we are able to tnsping from primary to DR
Tnsping Results
From Primary:
juemdbp1:oranpp 19> tnsping NPP_DR
TNS Ping Utility for HPUX: Version 10.2.0.4.0 - Production on 19-JAN-2011 09:32:50
Copyright (c) 1997, 2007, Oracle. All rights reserved.
Used parameter files:
/oracle/NPP/102_64/network/admin/sqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (COMMUNITY = SAP.WORLD) (PROTOCOL = TCP) (HOST = 10.80.51.101) (PORT = 49160))) (CONNECT_DATA = (SID = NPP) (SERVER = DEDICATED)))
OK (60 msec)
Tnsnames.ora in Primary:
Filename......: tnsnames.ora
Created.......: created by SAP AG, R/3 Rel. >= 6.10
Name..........:
Date..........:
@(#) $Id: //bc/700-1_REL/src/ins/SAPINST/impl/tpls/ora/ind/TNSNAMES.ORA#4 $
NPP.WORLD=
(DESCRIPTION =
    (ADDRESS_LIST =
        (ADDRESS =
          (COMMUNITY = SAP.WORLD)
          (PROTOCOL = TCP)
          (HOST = nppjorp)
          (PORT = 49160)
    (CONNECT_DATA =
       (SID = NPP)
       (GLOBAL_NAME = NPP.WORLD)
NPP_HQ.WORLD=
(DESCRIPTION =
   (ADDRESS_LIST =
        (ADDRESS =
          (COMMUNITY = SAP.WORLD)
          (PROTOCOL = TCP)
          (HOST = nppjorp)
          (PORT = 49160)
   (CONNECT_DATA =
        (SID = NPP)
        (SERVER = DEDICATED)
NPP_DR.WORLD=
(DESCRIPTION =
(ADDRESS_LIST =
   (ADDRESS =
        (COMMUNITY = SAP.WORLD)
        (PROTOCOL = TCP)
        (HOST = 10.80.51.101)
        (PORT = 49160)
(CONNECT_DATA =
        (SID = NPP)
        (SERVER = DEDICATED)
NPPLISTENER.WORLD=
        (DESCRIPTION =
          (ADDRESS =
                (PROTOCOL = TCP)
                (HOST = nppjorp)
                (PORT = 49160)
Listener.ora in Primary
Filename......: listener.ora
Created.......: created by SAP AG, R/3 Rel. >= 6.10
Name..........:
Date..........:
@(#) $Id: //bc/700-1_REL/src/ins/SAPINST/impl/tpls/ora/ind/LISTENER.ORA#4 $
ADMIN_RESTRICTIONS_LISTENER = on
LISTENER =
(ADDRESS_LIST =
        (ADDRESS =
          (PROTOCOL = IPC)
          (KEY = NPP.WORLD)
        (ADDRESS=
          (PROTOCOL = IPC)
          (KEY = NPP)
        (ADDRESS =
          (COMMUNITY = SAP.WORLD)
          (PROTOCOL = TCP)
          (HOST = nppjorp)
          (PORT = 49160)
STARTUP_WAIT_TIME_LISTENER = 0
CONNECT_TIMEOUT_LISTENER = 10
TRACE_LEVEL_LISTENER = OFF
SID_LIST_LISTENER =
(SID_LIST =
    (SID_DESC =
      (SID_NAME = NPP)
      (ORACLE_HOME = /oracle/NPP/102_64)
Thank You,
Salman Qayyum
Edited by: Salman M.A. Qayyum on Jan 19, 2011 8:12 AM

Hi,
Please find the remaining post ...
Tnsnames.ora in DR:
Filename......: tnsnames.ora
Created.......: created by SAP AG, R/3 Rel. >= 6.10
Name..........:
Date..........:
@(#) $Id: //bc/700-1_REL/src/ins/SAPINST/impl/tpls/ora/ind/TNSNAMES.ORA#4 $
NPP.WORLD=
(DESCRIPTION =
    (ADDRESS_LIST =
        (ADDRESS =
          (COMMUNITY = SAP.WORLD)
          (PROTOCOL = TCP)
          (HOST = nppjor)
          (PORT = 49160)
    (CONNECT_DATA =
       (SID = NPP)
       (GLOBAL_NAME = NPP.WORLD)
NPP_HQ.WORLD=
(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS =
        (COMMUNITY = SAP.WORLD)
        (PROTOCOL = TCP)
        (HOST = hq_nppjor)
        (PORT = 49160)
    (CONNECT_DATA =
        (SID = NPP)
        (SERVER = DEDICATED)
NPP_DR.WORLD=
(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS =
        (COMMUNITY = SAP.WORLD)
        (PROTOCOL = TCP)
        (HOST = nppjor)
        (PORT = 49160)
    (CONNECT_DATA =
        (SID = NPP)
        (SERVER = DEDICATED)
        (SERVICE_NAME = NPP_DR)
NPPLISTENER.WORLD=
        (DESCRIPTION =
          (ADDRESS =
                (PROTOCOL = TCP)
                (HOST = nppjor)
                (PORT = 49160)
Listener.ora in DR
Filename......: listener.ora
Created.......: created by SAP AG, R/3 Rel. >= 6.10
Name..........:
Date..........:
@(#) $Id: //bc/700-1_REL/src/ins/SAPINST/impl/tpls/ora/ind/LISTENER.ORA#4 $
ADMIN_RESTRICTIONS_LISTENER = on
LISTENER =
(ADDRESS_LIST =
        (ADDRESS =
          (PROTOCOL = IPC)
          (KEY = NPP.WORLD)
        (ADDRESS=
          (PROTOCOL = IPC)
          (KEY = NPP)
        (ADDRESS =
          (COMMUNITY = SAP.WORLD)
          (PROTOCOL = TCP)
          (HOST = nppjor)
          (PORT = 49160)
       (ADDRESS =
         (COMMUNITY = SAP.WORLD)
         (PROTOCOL = TCP)
         (HOST = 10.80.50.101)
         (PORT = 49160)
STARTUP_WAIT_TIME_LISTENER = 0
CONNECT_TIMEOUT_LISTENER = 10
TRACE_LEVEL_LISTENER = OFF
SID_LIST_LISTENER =
(SID_LIST =
    (SID_DESC =
      (SID_NAME = NPP)
      (ORACLE_HOME = /oracle/NPP/102_64)
/etc/hosts settings in Primary
host:oranpp 25> grep nppjor /etc/hosts
10.32.243.54    nppjor.sabic.com        nppjor
10.32.50.115    nppjorp.sabic.com        nppjorp
/etc/hosts settings in DR
host:oranpp 11> grep nppjor /etc/hosts
10.32.243.54    hq_nppjor.sabic.com     hq_nppjor
10.80.243.54    nppjor.sabic.com        nppjor
10.80.50.115    nppjorp.sabic.com        nppjorp
Thank You,
Salman Qayyum

What does redo log buffer holds, changed value or data block?

Hello Everyone,
i am new to database side and have one query as i know redo log buffer contain change information , my doubt is does it store the value only or the changed data block? because if we can see data buffer cache size is more as it holds data block and redo log buffer size is less .

The Redo Log buffer contains OpCodes that represent the SQL commands, the "address" (file,block,row) where the change is to be made and the nature of the change.
It does NOT contain the data block.
(the one exception is when you run a User Managed Backup with ALTER DATABASE BEGIN BACKUP or ALTER TABLESPACE BEGIN BACKUP : The first time a block is modified when in BEGIN BACKUP mode, the whole block is written to the redo stream).
The log buffer can be and is deliberately smaller than the blocks buffer cache. Entries in the redo log buffer are quickly written to disk (at commits, when it is 1/3rd or 1MB full, every 3seconds, before DBWR writes a modified data block).
Hemant K Chitale

Data Guard : Standby Redo Log CONFUSION

Trying to set up test Standby db on 10.2.0
I am well confused about below step 3.1.3, how is the normal redo linked with standby redo, should standby not be members of orginal redo groups?
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/create_ps.htm#i1225703
Original redo logs:
SQL> select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIME
         1          1         28   52428800          1 YES INACTIVE                375136 22-NOV-07
         2          1         29   52428800          1 YES INACTIVE                375138 22-NOV-07
         3          1         30   52428800          1 NO CURRENT                 375143 22-NOV-07I added below from notes:
ALTER DATABASE ADD STANDBY LOGFILE GROUP 10
('/u01/oracle/oradata/db01/redo01_stb.log') SIZE 50M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 11
('/u02/oracle/oradata/db01/redo02_stb.log') SIZE 50M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 12
('/u03/oracle/oradata/db01/redo03_stb.log') SIZE 50M;After few alter system switch logfile; I still have:
    GROUP#    THREAD# SEQUENCE# ARC STATUS
        10          0          0 YES UNASSIGNED
        11          0          0 YES UNASSIGNED
        12          0          0 YES UNASSIGNEDAll are UNASSIGNED, should one standby group not be ACTIVE like the above link shows.
Many think for any help

First things first:
From the Docs.:
"Minimally, the configuration should have one more standby redo log file group than the number of online redo log file groups on the primary database. However, the recommended number of standby redo log file groups is dependent on the number of threads on the primary database. Use the following equation to determine an appropriate number of standby redo log file groups:
(maximum number of logfiles for each thread + 1) * maximum number of threads
Using this equation reduces the likelihood that the primary instance's log writer (LGWR) process will be blocked because a standby redo log file cannot be allocated on the standby database. For example, if the primary database has 2 log files for each thread and 2 threads, then 6 standby redo log file groups are needed on the standby database."
You are 1 short!

How to disable write to redo log file in oracle7.3.4

in oracle 8, alter table no logged in redo log file like: alter table tablename nologging;
how to do this in oracle 7.3.4?
thanks.

user652965 wrote:
Thanks very much for your help guys. I appreciate it. unfortunately none of these commands worked for me. I kept getting error on clearing logs that redo log is needed to perform recovery so it can't be cleared. So I ended up restoring from earlier snapshot of my db volume. Database is now open.
Thanks again for your input.And now, as a follow-up, at a minimum you should make sure that all redo log groups have at least 3 members. Then, if you lose a single redo log file, all you have to do is shutdown the db and copy one of the good members (of the same group as the lost member) over the lost member.
And as an additional follow-up, if you value your data you will run in archivelog mode and take regular backups of the database and archivelogs. If you fail to do this you are saying that your data is not worth saving.

Problem in creating database -Missing Redo log file

I am try to create a new database using DBCA .While creating a database it shows the error oracle instance terminated.Force Disconnected.
My alert log file is
Errors in file /u01/app/oracle/diag/rdbms/oracl/oracl/trace/oracl_ora_5424.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/oracl/redo01.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Wed Nov 06 10:07:27 2013
Errors in file /u01/app/oracle/diag/rdbms/oracl/oracl/trace/oracl_ora_5424.trc:
ORA-00313: open failed for members of log group 2 of thread 1
ORA-00312: online log 2 thread 1: '/u01/app/oracle/oradata/oracl/redo02.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Errors in file /u01/app/oracle/diag/rdbms/oracl/oracl/trace/oracl_ora_5424.trc:
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/u01/app/oracle/oradata/oracl/redo03.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Wed Nov 06 10:07:38 2013
Setting recovery target incarnation to 2
Wed Nov 06 10:07:38 2013
Assigning activation ID 1876274518 (0x6fd5ad56)
Thread 1 opened at log sequence 1
Current log# 1 seq# 1 mem# 0: /u01/app/oracle/oradata/oracl/redo01.log
Successful open of redo thread 1
Wed Nov 06 10:07:38 2013
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Wed Nov 06 10:07:38 2013
SMON: enabling cache recovery
Errors in file /u01/app/oracle/diag/rdbms/oracl/oracl/trace/oracl_ora_5424.trc (incident=1345):
ORA-00600: internal error code, arguments: [kpotcgah-7], [12534], [ORA-12534: TNS:operation not supported
Incident details in: /u01/app/oracle/diag/rdbms/oracl/oracl/incident/incdir_1345/oracl_ora_5424_i1345.trc
Wed Nov 06 10:07:46 2013
Trace dumping is performing id=[cdmp_20131106100746]
Errors in file /u01/app/oracle/diag/rdbms/oracl/oracl/trace/oracl_ora_5424.trc:
ORA-00600: internal error code, arguments: [kpotcgah-7], [12534], [ORA-12534: TNS:operation not supported
Error 600 happened during db open, shutting down database
USER (ospid: 5424): terminating the instance due to error 600
Instance terminated by USER, pid = 5424
ORA-1092 signalled during: alter database "oracl" open resetlogs...
ORA-1092 : opiodr aborting process unknown ospid (5424_47935551851664)
Wed Nov 06 10:07:47 2013
ORA-1092 : opitsk aborting process
251,1 95%

>I am try to create a new database using DBCA
>Please help me to resolve this issue.My redo log file was missing
DROP and recreate the database. It is a *new* database without any data.
Check what datafile locations and redo log file locations you specify when creating the new database. Check if you have permissions and enough disk space.
Hemant K Chitale

How to remove a redo log file

Hi Experts,
I want to remove a wrong redo log file from 10G R2 database in window.
how to do that without loss data?
my steps as
1. alter system switch logfile;
2. select * from v$log;
which ARC and sataus do I can drop redo log file based on above SQL
no archive and active status?
ALso Which account should I do above action?
fExamp, system account added redo log file, i only
can drop by system? how about sys?
Thanks help in detail steps
Jim
Edited by: user589812 on Dec 23, 2008 4:35 PM

Jim,
Check this link out for how to drop a redo log file
Make sure a redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the V$LOG view.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm#i1006489
SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
   GROUP# ARC STATUS
        1 YES ACTIVE
        2 NO CURRENT
        3 YES INACTIVE
        4 YES INACTIVE
Drop a redo log group with the SQL statement ALTER DATABASE with the DROP LOGFILE clause.
The following statement drops redo log group number 3:
ALTER DATABASE DROP LOGFILE GROUP 3;

Restore in noarchivelog mode ( redo log files have been dropped )

1, A full backup taken using RMAN is available on disk.
2, The current control files were NOT damaged and do not need to be restored.
3, All data files are damaged .
4, The database is in NOARCHIVELOG mode.
I restore database :
1. RMAN> STARTUP MOUNT
2. RMAN> RESTORE DATABASE;
3. RMAN> recover database;
in this step , I got the information about needing redo log files ; but the redo log
files have been dropped , what should i do ?
else
I want to know there is the command 'recover database using backup control file'
in rman or not ?
Tks

Possibly loss of data (because information in online redo logs is lost):
recover database until cancel;
(cancel immediately)
alter database open resetlogs; (to build a new set of redo logs)
It's not necessary to use a backup controlfile here.

Redo log data

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