Redo log on disk - do I need to multiplex them?

Hello,
I'm running my 10gR2 EE DB on SPARC server.
Currently we are running whole DB on FC LUN mounted as /u01
My folder structure is (for example):
/u01/oracle (binaries)
/u01/oradata
/u01/oraindex
/u01/oraredo1
/u02/oraredo2
/u03/oreredo3
Well, the problem is (or there is no problem :), do I really need to multiply my redo groups on 3 locations, while all of those locations are from the same FC disk array (with RAID of example)?
I have 5 groups with 3 members.
In addition: sometimes I get log_file_sync wait event.
Regards
Edited by: zawierta on 2011-02-14 01:07

Well, Oracle recommends (minimum) 2 members per group, and to use 2 separate storage. So, one location on your shared storage, and the other on your local disks is already better than both on same location.
Concerning log file sync wait event , i have found the following :
High log file sync wait event
http://www.dba-oracle.com/t_log_file_sync_waits.htm
http://christianbilien.wordpress.com/2008/02/12/the-%E2%80%9Clog-file-sync%E2%80%9D-wait-event-is-not-always-spent-waiting-for-an-io/
HTH,
Thierry

Similar Messages

When changing redo-logs on Primary, do I need to change my standby also?

Hi, I need to resize my redo logs on a primary db which has a physical standby attached. Do I need to modify this standby or will the change propagate. It seems unlikely to me.
thanx

Only clue that I have found is at
http://download-east.oracle.com/docs/cd/B12037_01/server.101/b10726/configbp.htm
Section "Use Multiplexed Standby Redo Logs and Configure Size Appropriately"
>>
The remote file server (RFS) process for the standby database writes only to an SRL whose size is identical to the size of an online redo log for the production database. If it cannot find an appropriately sized SRL, then RFS creates an archived redo log file directly instead and logs the following message in the alert log:
No standby redo log files of size <#> blocks available.
>>

Redo log and Disk Full

hi
all
i'm new oracle DBA. i had one problem is
my Database is in archive mode. now redo log is available but not archive and my disk is full. so i couldn't open my Database what i have to do next step please help me...
Thanks in advance
Dharmesh
null

Take a proper copy of all the archived log files from the archive destination to some backup media like tape(for future recoverability) and delete them off from the disk to avail for space on the disk.
You will then be able to open your DB and proper archiving will take place.
What is happening?
The ARCHiver process is finding no space on the disk to archive the redo log files and thus Oracle stops doing any further action since it is in archive log mode.

Usage of Redo Log Groups & Disk Contention

Hi,
I have a peculiar problem here.
I have the redo log groups/members configured in the following manner.Please note that the disks are in the A-B-A-B-A-B sequence for successive redo groups.
GROUP#      MEMBER
11      /origlogA/log_g11m1.dbf
11      /mirrlogA/log_g11m2.dbf
12      /origlogB/log_g12m1.dbf
12      /mirrlogB/log_g12m2.dbf
13      /origlogA/log_g13m1.dbf
13      /mirrlogA/log_g13m2.dbf
14      /origlogB/log_g14m1.dbf
14      /mirrlogB/log_g14m2.dbf
15      /origlogA/log_g15m1.dbf
15      /mirrlogA/log_g15m2.dbf
16      /origlogB/log_g16m1.dbf
16      /mirrlogB/log_g16m2.dbf
17      /origlogA/log_g17m1.dbf
17      /mirrlogA/log_g17m2.dbf
18      /origlogB/log_g18m1.dbf
18      /mirrlogB/log_g18m2.dbf
19      /origlogA/log_g19m1.dbf
19      /mirrlogA/log_g19m2.dbf
20      /origlogB/log_g20m1.dbf
20      /mirrlogB/log_g20m2.dbf
21      /origlogA/log_g21m1.dbf
21      /mirrlogA/log_g21m2.dbf
22      /origlogB/log_g22m1.dbf
22      /mirrlogB/log_g22m2.dbf
23      /origlogA/log_g23m1.dbf
23      /mirrlogA/log_g23m2.dbf
24      /origlogB/log_g24m1.dbf
24      /mirrlogB/log_g24m2.dbf
But oracle uses these groups in a zig-zag manner(pls refer the list below).Here, after group# 15, it is group# 11 , which is used. And the members of these two groups are in the same set of disks ie; "/origlogA and /mirrlogA"
(Note:The following result is ordered by sequence #)
GROUP# SEQUENCE#      MEMBER
16      263076           /origlogB/log_g16m1.dbf
16      263076           /mirrlogB/log_g16m2.dbf
17      263077           /origlogA/log_g17m1.dbf
17      263077           /mirrlogA/log_g17m2.dbf
18      263078           /origlogB/log_g18m1.dbf
18      263078           /mirrlogB/log_g18m2.dbf
19      263079           /origlogA/log_g19m1.dbf
19      263079           /mirrlogA/log_g19m2.dbf
20      263080           /origlogB/log_g20m1.dbf
20      263080           /mirrlogB/log_g20m2.dbf
21      263081           /origlogA/log_g21m1.dbf
21      263081           /mirrlogA/log_g21m2.dbf
22      263082           /origlogB/log_g22m1.dbf
22      263082           /mirrlogB/log_g22m2.dbf
23      263083           /origlogA/log_g23m1.dbf
23      263083           /mirrlogA/log_g23m2.dbf
24      263084           /origlogB/log_g24m1.dbf
24      263084           /mirrlogB/log_g24m2.dbf
13      263085           /origlogA/log_g13m1.dbf
13      263085           /mirrlogA/log_g13m2.dbf
14      263086           /origlogB/log_g14m1.dbf
14      263086           /mirrlogB/log_g14m2.dbf
15      263087           /origlogA/log_g15m1.dbf
15      263087           /mirrlogA/log_g15m2.dbf
11      263088           /origlogA/log_g11m1.dbf
11      263088           /mirrlogA/log_g11m2.dbf
12      263089           /origlogB/log_g12m1.dbf
12      263089           /mirrlogB/log_g12m2.dbf
Is there anyway, which we can force oracle to use the log groups in the right succession of log groups ? (like 11-12-13-14-15-16-17-18-19-20 etc.).
I want to make sure that there will be no chances of contention, due to the "archiving of the offline redo log & LGWR writing to the online redo log" happening on the same disk.
Thanks in advance,
Don

Hi,
There's no way to achieve what you're trying to do except:
1/ switch logfile till the current group is the last one.
2/ drop groups from 1 to (last - 2)
3/ create groups 1, 2, 3 (or 11, 12, 13, 14, ... don't care)
4/ Switch logfile Twice
5/ Alter system checkpoint
6/ Drop the former 2 or 3 remaining groups (19, 20, 21, ...)
7/ Recreate them.
But i'd like to point that having them go in order is perfectly useless.
And that you're a priori doing something dangerous. Having your log members on the same disk for the different groups. usually I'd choose to
. Put member 1 on disk 1
. Put member 2 on disk 2
. Increase the number of archiver processes
. ensure disk 1 and 2 are not RAID disk(click)
Regards,
Yoann.

Why do we need standby redo log on Primary database.

Hi Gurus,
I was going through the document in OBE,
http://www.oracle.com/technology/obe/11gr1_db/ha/dataguard/physstby/physstdby.htm
I have two queries:
1) I noticed the statement -
"Configure the primary database to receive redo data, by adding the standby logfiles to the primary. "
Why do we have to create standby redo log on a primary database?
2) There is another statement --
"It is highly recommended that you have one more standby redo log group than you have online redo log groups as the primary database. The files must be the same size or larger than the primary database’s online redo logs. "
Why do we need one additional standby redo log group than in Primary database.
Could anyone please explain to me in simple words.
Thanks
Cherrish Vaidiyan

Hi,
1. Standby redo logs are used only when the database_role is standby, it is recommended to be added in primary also so that they can be used on role reversal, however during normal working standby redo logs will not be used at all on primary.
2. In case of 3 online redo log groups, it is recommended to use 4 standby redo log group this is in case if log switching is happening frequently on primary and all 3 standby redo logs are still not completely archived on the standby and 4th can be used here as there will be some delay on standby due to network or slowness of arch on standby.
Use of the standby redo log groups depends on the redo generation rate, you can see only 2 standby redo logs are getting used while you have 4 standby redo log groups, when the redo generation rate is less.
So it is recommended to have one more standby redo log group when redo generation rate is high and all of the existing standby redo log group are getting used.
Regards
Anudeep

Hoping for a quick response : EXP and Archived REDO log files

I apologize in advance if this question has been asked and answered 100 times. I admit I didn't search, I don't have time. I'm leaving on vacation tomorrow, and I need to know if I'm correct about something to do with backup / restore.
we have 10g R2 running a single instance on a single server. The application vendor has "embedded" oracle with their application. The vendor's backup is a batch file using EXP - thus:
exp system/xpwdxx@db full=y file=D:\Orant\admin\db\EXP\db_full.dmp log=D:\Orant\admin\db\EXP\db_full.txt direct=y compress=y
This command is executed nightly at midnight. The files are then backed up by our nightly backup to offsite storage media.
Te database is running in autoarchive mode. The problem is, the archived redo files filled the drive they were being stored on, and it is the drive the database is on. I used OS commands to move 136G of archived redo logs onto other storage media to free the drive.
My question: Since the EXP runs at midnight, when there is likely NO activity, do I need to run in AutoArchive Mode? From what I have read, you cannot even apply archived redo log files to this type of backup strategy (IMP) Is that true? We are ok losing changes since our last EXP. I have read a lot of stuff about restoring consistent vs. inconsistent, and just need to know: If my disk fails, and I have to start with a clean install of Oracle and nothing else, can I IMP this EXP and get back up and running as of the last EXP? Or do I need the autoarchived redo log files back to July 2009 (136G of them).
Hoping for a quick response
Best Regards, and thanks in advance
Bruce Davis

Bruce Davis wrote:
Amardeep Sidhu
Thank you for your quick reply. I am reading in the other responses that since I am using EXP without consistent=y, I might not even have a backup. The application vendor said that with this dmp file they can restore us to the most recent backup. I don't really care for this strategy as it is untested. I asked them to verify that they could restore us and they said they tested the dmp file and it was OK.
Thank you for taking the time to reply.
Best Regards
BruceThe dump file is probably ok in the sense it is not corrupted and can be used in an imp operation. That doesn't mean the data in it is transactionally consistent. And to use it at all, you have to have a database up and running. If the database is physically corrupted, you'll have to rebuild a new database from scratch before you can even think about using your dmp file.
Vendors never understand databases. I once had a vendor tell me that Oracle's performance would be intolerable if there were more than 5 concurrent connections. Well, maybe in HIS product ..... Discussions terminated quickly after he made that statement.

Physical standby database standby redo log problem

Hello
We have a physical standby database , I've created some standby redo log files but my problem is that they aren't used,
their status in v$stanby_log view is UNASSIGNED
and I see this message (ORA-16086: standby database does not contain available standby log files) in primary database alert_log file
while when I run "alter system switch logfile" in the primary database it transfer redo logs to the physsical standby database
and archive log file will be created in standby database
I've even recreated the standby redo log files and I added new ones to them but the problem wasn't solved
Do you know what is problem ?
elect group#,THREAD#,BYTES,STATUS from V$STANDBY_LOG;
group#     THREAD#      BYTES       STATUS
1                   0                   524288000                   UNASSIGNED
2                   0                   524288000                   UNASSIGNED
3                   0                   524288000                   UNASSIGNED
8                   0                   524288000                   UNASSIGNED
9                   0                   524288000                   UNASSIGNED
10                   0                   524288000                   UNASSIGNED
select group#,THREAD#,BYTES,MEMBERS,STATUS from v$log;
group#                    THREAD#                    BYTES                    MEMBERS                    STATUS
4                   1                   524288000                   2                   CLEARING
7                   1                   524288000                   2                   CLEARING_CURRENT
6                   1                   524288000                   2                   CLEARING
5                   1                   524288000                   2                   CLEARING
thanks

Hello Anurag
Thank you for your reply
I have found some issue in the standby database alert_log too , in the standby database alert_log it has been written:
RFS[782]: Assigned to RFS process 3919
RFS[782]: Identified database type as 'physical standby'
Primary database is in MAXIMUM AVAILABILITY mode
Standby controlfile consistent with primary
Primary database is in MAXIMUM AVAILABILITY mode
Standby controlfile consistent with primary
RFS[782]: No standby redo logfiles selected (reason:6)
Sun Jan 31 13:59:43 2010
Errors in file /u01/app/oracle/admin/tehrep/udump/tehrep_rfs_3919.trc:
ORA-16086: standby database does not contain available standby log files
Sun Jan 31 13:59:48 2010
RFS[781]: Archived Log: '/disks/sda/tehrep/archivelogs/1_6516_670414641.dbf'
Sun Jan 31 13:59:50 2010
and the context "/u01/app/oracle/admin/tehrep/udump/tehrep_rfs_3919.trc" is below :
+/u01/app/oracle/admin/tehrep/udump/tehrep_rfs_3919.trc+
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1
System name:    Linux
Node name:      linserver2.com
Release:        2.6.9-42.ELsmp
Version:        #1 SMP Wed Jul 12 23:27:17 EDT 2006
Machine:        i686
Instance name: tehrep
Redo thread mounted by this instance: 1
Oracle process number: 58
Unix process pid: 3919, image: [email protected]
*** SERVICE NAME:() 2010-01-31 13:59:43.865
*** SESSION ID:(109.1225) 2010-01-31 13:59:43.865
KCRRFLAS
KCRRSNPS
No space in recovery area for active standby redo logs
The primary database is operating in MAXIMUM PROTECTION
or MAXIMUM AVAILABILITY mode, and the standby database
does not contain adequate disk space in the recovery area
to safely archive the contents of the standby redo logfiles.
ORA-16086: standby database does not contain available standby log files
when I saw this line "No space in recovery area for active standby redo logs" I thought that STANDBY_ARCHIVE_DEST parameter points where that there is no enough space , but when I consider I found out that points a directory on disk a "sda" that has enough space , I don't know what that means
by the way, at below I've written a section of the primary database alert_log context and "lgwr" trace file around Sun Jan 31 13:30:34 2010
alert_log :
ORA-16086: standby database does not contain available standby log files
Sun Jan 31 13:30:34 2010
LGWR: Failed to archive log 7 thread 1 sequence 6512 (16086)
Thread 1 advanced to log sequence 6512
Current log# 7 seq# 6512 mem# 0: /disks/sdb/tehrep/redo71.log
Current log# 7 seq# 6512 mem# 1: /disks/sdd/tehrep/redo72.log
LNSc started with pid=53, OS id=11451
Sun Jan 31 13:36:34 2010
Errors in file /u01/app/oracle/admin/tehrep/bdump/tehrep_lgwr_3692.trc:
ORA-16086: standby database does not contain available standby log files
Sun Jan 31 13:36:34 2010
LGWR: Failed to archive log 5 thread 1 sequence 6513 (16086)
Thread 1 advanced to log sequence 6513
Current log# 5 seq# 6513 mem# 0: /disks/sdb/tehrep/redo51.log
Current log# 5 seq# 6513 mem# 1: /disks/sdd/tehrep/redo52.log
*/u01/app/oracle/admin/tehrep/bdump/tehrep_lgwr_3692.trc file :*
Error 16086 creating standby archive log file at host '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=linserver2.com
+)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=tehrep_XPT.com)(INSTANCE_NAME=tehrep)(SERVER=dedicated)))'+
*** 2010-01-31 13:30:34.712 60679 kcrr.c
LGWR: Attempting destination LOG_ARCHIVE_DEST_3 network reconnect (16086)
*** 2010-01-31 13:30:34.712 60679 kcrr.c
LGWR: Destination LOG_ARCHIVE_DEST_3 network reconnect abandoned
ORA-16086: standby database does not contain available standby log files
*** 2010-01-31 13:30:34.712 60679 kcrr.c
LGWR: Error 16086 creating archivelog file '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=linserver2.com)(PORT=1521
+)))(CONNECT_DATA=(SERVICE_NAME=tehrep_XPT.com)(INSTANCE_NAME=tehrep)(SERVER=dedicated)))'+
*** 2010-01-31 13:30:34.712 58941 kcrr.c
kcrrfail: dest:3 err:16086 force:0 blast:1
Receiving message from LNSc
*** 2010-01-31 13:30:34.718 55444 kcrr.c
Making upidhs request to LNSc (ocis 0x0xb648db48). Begin time is <01/31/2010 13:30:30> and NET_TIMEOUT <180> seconds
NetServer pid:11196
*** 2010-01-31 13:30:38.718 55616 kcrr.c
upidhs done status 0
*** 2010-01-31 13:36:31.062
LGWR: Archivelog for thread 1 sequence 6513 will NOT be compressed
*** 2010-01-31 13:36:31.062 53681 kcrr.c
+Initializing NetServer[LNSc] for dest=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=linserver2.com)(PORT=1521)))(CO+
NNECT_DATA=(SERVICE_NAME=tehrep_XPT.com)(INSTANCE_NAME=tehrep)(SERVER=dedicated))) mode SYNC
LNSc is not running anymore.
New SYNC LNSc needs to be started
Waiting for subscriber count on LGWR-LNSc channel to go to zero
Subscriber count went to zero - time now is <01/31/2010 13:36:31>
Starting LNSc ...
Waiting for LNSc to initialize itself
*** 2010-01-31 13:36:34.116 53972 kcrr.c
+Netserver LNSc [pid 11451] for mode SYNC has been initialized+
Performing a channel reset to ignore previous responses
+Successfully started LNSc [pid 11451] for dest (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=linserver2.com)(PORT=1+
+521)))(CONNECT_DATA=(SERVICE_NAME=tehrep_XPT.com)(INSTANCE_NAME=tehrep)(SERVER=dedicated))) mode SYNC ocis=0x0xb648db48+
*** 2010-01-31 13:36:34.116 54475 kcrr.c
+Making upiahm request to LNSc [pid 11451]: Begin Time is <01/31/2010 13:36:31>. NET_TIMEOUT = <180> seconds+
Waiting for LNSc to respond to upiahm
*** 2010-01-31 13:36:34.266 54639 kcrr.c
upiahm connect done status is 0
Receiving message from LNSc
Receiving message from LNSc
Destination LOG_ARCHIVE_DEST_3 is in STANDBY RESYNCHRONIZATION mode
Receiving message from LNSc

Current redo log file is lost

Hi All,
I got a scenario in which my current redo log file is lost:
Do I need to:
1)Clear log file group
(or)
2)I should perform incomplete recovery.
What are the steps I should follow to recover this current redo log file?
1)*If it is inactive* I can make use of
ALTER DATABASE CLEAR LOGFILE UNARCHIVED GROUP 2;
which will drop and recreate the log file.To recover from loss of an active online log group in NOARCHIVELOG mode:
If the media failure is temporary, then correct the problem so that the database can reuse the group when required.
Restore the database from a consistent, whole database backup (datafiles and control files) as described in "Restoring Datafiles Before Performing Incomplete Recovery". For example, enter:
% cp /disk2/backup/*.dbf $ORACLE_HOME/oradata/trgt/
Mount the database:
STARTUP MOUNT
Because online redo logs are not backed up, you cannot restore them with the datafiles and control files. In order to allow the database to reset the online redo logs, you must first mimic incomplete recovery:
RECOVER DATABASE UNTIL CANCEL
CANCEL
Open the database using the RESETLOGS option:
ALTER DATABASE OPEN RESETLOGS;
Shut down the database consistently. For example, enter:
SHUTDOWN IMMEDIATE
Make a whole database backup.
To recover from loss of an active online redo log group in ARCHIVELOG mode:
If the media failure is temporary, then correct the problem so that the database can reuse the group when required. If the media failure is not temporary, then use the following procedure.
Begin incomplete media recovery, recovering up through the log before the damaged log.
Ensure that the current name of the lost redo log can be used for a newly created file. If not, then rename the members of the damaged online redo log group to a new location. For example, enter:
ALTER DATABASE RENAME FILE "?/oradata/trgt/redo01.log" TO "/tmp/redo01.log";
ALTER DATABASE RENAME FILE "?/oradata/trgt/redo01.log" TO "/tmp/redo02.log";
Open the database using the RESETLOGS option:
ALTER DATABASE OPEN RESETLOGS;
My question is when the redo log file is current. What steps we should follow?
Best regards,
Rafi.
http://rafioracledba.blogspot.com/
2)If it is active then I can make use of below steps:

Rafi (Oracle DBA) wrote:
Hi Asif,
This link I have seen by refering to previous post.I just have a slight doubt in mind.
1)Do I need to make use of statement:
Alter database clear unarchived log file group#;
(or)
Only if your group is current(or you are not able to drop it) and is not archived then you should use above query.
We should perform incomplete recovery for this.If we have to perform incomplete recovery what are the steps I should follow?
I doubt you should be performing incomplete recovery for this.
Eg:Let us say my group 1 is dropped it has only one member and it is in active state.How to recover database?Can I get the steps?
You would not be able to drop it if it is in active state, did you meant it is corrupted? If yes then you can use below query
Alter database clear [unarchived] LOGFILE GROUP #;>
Best regards,
Rafi
http://rafioracledba.blogspot.com/
Make sure to backup your database after above activity.
Regards
Anurag

Application of online redo logs

Dear all,
In my organisation recently standby database has been configured. Now my task is to restore a full online+redo backup which is created in primary database in the standby database. Once it is over I have to apply the newly created redo logs generated after the online backup.
I am planning to restore the online+redo backup using the following command
brrestore -b "BRBACKUP log file" -m full. Once it is done I have to apply the online redo logs. I am confused how to apply manually the newly created redo logs. Is there any document regarding it. I searched and found many information in net but nothing seems to be very convincing as this is a critical activity.
Best Regards,
Tapan

Hello Tapan,
> brrestore -b "BRBACKUP log file" -m full. Once it is done I have to apply the online redo logs.
Bad idea, you need a standby controlfile and not a backup controlfile on the standby site.
> I am confused how to apply manually the newly created redo logs. Is there any document regarding it.
You can do this manually by your own or by Oracle Dataguard.
I would suggest that you get a training on Oracle Dataguard and then you will understand the concepts and will be able to setup a DR solution. It makes not much sense to explain you all the steps and the functions, because of in a critical moment you should know what to do and why.
If you really want to try it by your own - so start with this:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/toc.htm
http://download.oracle.com/docs/cd/B19306_01/server.102/b14230/toc.htm
Regards
Stefan

When is anything written to standby redo logs on standby database?

I am on Oracle 10.2.0.4 on HP UNIX. I have read Oracle 10.2 concepts guide on technet.oracle.com, have read may article on metalink and internet, yet I am unable to verify when anything is written to standby redo logs on stand by database.
I have a simple database reconfiguration: a primary database and one standby database.
I created primary database and set up log_archive_dest_2 to use LGWR SYNC AFFIRM
I have created standby redo logs on primary.
alter database add standby logfile GROUP
I create standby control file on primary.
I copied all the primary information to create standby database. I have put standby database in managed recovery.
I did archive log switches, I created a table and inserted information in table.
I never saw standby redo logs updated on standby database by looking at timestamp of standby redo log files.
I then setup database in maximum availability mode by running following on primary:
Alter database set standby database to maximize availability
When I do insert into my tables, I do see standby redo log files on primary database being updated, but I have never seen standby redo logs on standby database updated. Why?
I am still at loss when actually standby redo logs are updated on standby database.
When I read Oracle 9i database documentation on data guard, it says that you do not need standby redo logs on primary instead you need them on standby. Only reason, you need them on primary is from primary changes role to standby database, so standby redo logs on standby database should be updated instead of standby redo logs on primary.

What is the PROTECTION_MODE ,PROTECTION_LEVEL values of your database.
As per metalink:--
Create standby redo log files, if necessary:
Standby redo logs are necessary for the higher protection levels such as
Guaranteed, Instant, and Rapid. In these protection modes LGWR from the
Primary host writes transactions directly to the standby redo logs.
This enables no data loss solutions and reduces the amount of data loss
in the event of failure. Standby redo logs are not necessary if you are using
the delayed protection mode.
If you configure standby redo on the standby then you should also configure
standby redo logs on the primary database. Even though the standby redo logs
are not used when the database is running in the primary role, configuring
the standby redo logs on the primary database is recommended in preparation
for an eventual switchover operation.
Standby redo logs must be archived before the data can be applied to the
standby database. The standby archival operation occurs automatically, even if
the standby database is not in ARCHIVELOG mode. However, the archiver process
must be started on the standby database. Note that the use of the archiver
process (ARCn) is a requirement for selection of a standby redo log.
METALINK ID:- Doc ID: Note:219344.1
Edited by: Anand... on Sep 15, 2008 2:15 AM

What will heppen if redo logs at os level get deleted

Friends,
need 1 answer about the query: what will heppen if redo logs at os level get deleted.

how can i find where are my multiplexed redo logs, so that i can copy it from there
SQL> shutdown abort
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 534462464 bytes
Fixed Size                  2256912 bytes
Variable Size             398462960 bytes
Database Buffers          125829120 bytes
Redo Buffers                7913472 bytes
Database mounted.
SQL> select * from v$logfile
2 ;
    GROUP# STATUS TYPE
MEMBER
IS_
         3         ONLINE
C:\O\ORADATA\XE\REDO03.LOG
NO
         2         ONLINE
C:\O\ORADATA\XE\REDO02.LOG
NO
    GROUP# STATUS TYPE
MEMBER
IS_
         1         ONLINE
C:\O\ORADATA\XE\REDO01.LOG
NO                                         However, Oracle knows about the multiplexing, so if your logs were multiplexed properly (using redo log members), Oracle would already have known about them and identified that there was one available.
Just goes to show you (if this is, in fact what you did), don't just go blindly deleting files that have a ".LOG" extension.

Redo log backup failed

Hi,
My redo log backup failed and I've no clue on the errors. Below is the job log. Please advise. TIA !
Job started
Step 001 started (program RSDBAJOB, variant &0000000000064, user ID BACKUP_USER)
No application server found on database host - rsh/gateway will be used
Execute logical command BRARCHIVE On host bering
Parameters:-u / -jid LOG__20090313130000 -c force -p initprd.sap -cds
SXPG_COMMAND_EXECUTE(LONG)
COMMANDNAME = BRARCHIVE
OPERATINGSYSTEM = ANYOS
TARGETSYSTEM = bering
DESTINATION = SAPXPG_DBDEST_BERING
BR0002I BRARCHIVE 7.00 (32)
BR0181E Option '-cds' not supported for 'disk'
BR0007I End of offline redo log processing: aeactnyg.log 2009-03-13 13.00.19
BR0280I BRARCHIVE time stamp: 2009-03-13 13.00.21
BR0005I BRARCHIVE terminated with errors
External program terminated with exit code 3
BRARCHIVE returned error status E
Job finished
DL

Hi,
You tried to backup redo log on disk.
Option -cds (create second copy, delete and the first copy serial) is not supported when you do a redolog backup using disk as backup device type.
Try to change the option to -sd (save first copy and delete)
rgds,
fendhy.

When occurs crash recovery,why use active online redo log not archived log?

If current redo log had archived, but it's still 'ACTIVE'. As we all know, archived log is just an archived copy of the current redo log which is still 'ACTIVE', they have the same data. But why use active online redo log not archived log for crash recovery?(I think, if crash recovery can use archived log, then whether the online redo log is 'ACTIVE' or not, it can be overwritten)
Quote:
Re: v$log : How redo log file can have a status ACTIVE and be already archived?
Hemant K Chitale
If your instance crashes, Oracle attempts Instance Recovery -- reading from the Online Redo Logs. It doesn't need ArchiveLogs for Instance Recovery.
TanelPoder
Whether the log is already archived or not doesn't matter here, when the instance crashes, Oracle needs some blocks from that redolog. Archivelog is just an archived copy of the redolog, so you could use either the online or achive log for the recovery, it's the same data in there (Oracle reads the log/archivelog file header when it tries to use it for recovery and validates whether it contains the changes (RBA range) in it what it needs).

Aman.... wrote:
John,
Are you sure that the instance recovery (not the media recovery) would be using the archived redo logs? Since the only thing that would be lost is the isntance, there wouldn't be any archived redo log generated from the Current redo log and the previous archived redo logs, would be already checkpointed to the data file, IMHO archived redo logs won't participate in the instance recovery process. Yep, shall watch the video but tomorrow .
Regards
Aman....
That's what I said. Or meant to say. If Oracle used archivelogs for instance recovery, it would not be possible to recover in noarchive log mode. So recovery relies exclusively on the online log.
Sorry I wasted your time, I'll try to be less ambiguous in future

Redo log usage

Dear all,
Coud you please tell me that usage of redo log file.
is it only for recovery process.
shoul we backup it.
regrds
upul indika

Coud you please tell me that usage of redo log file.
typically redo log files are used for media recovery as well it can also be used for instance recovery,it is also used for standby database process.
is it only for recovery process.
shoul we backup it. Redo log is never backed up rather you multiplexed and archived even oracle own backup recovery tool RMAN never backup the redo log files ,redo log is used in cyclic manner if one goes full then it moves to another one (which is called log switch).In no archivelog the redo log is overwritten which will be no useful for the database file right now.In yours database what ever you perform first it goes to redo log and then to data files.You may think why redo log contains both un commited and commited values cause in case of any accident you may recover till before that accident.
Khurram

Best way to move redo log from one disk group to another in ASM?

Hi All,
Our db is 10.2.0.3 RAC db. And database servers are window 2003 server.
We need to move more than 50 redo logs (some are regular and some are standby) which are not redundant from one disk group to another. Say we need to move from disk group 1 to 2. Here are the options we are thinking about but not sure which one is the best from easiness and safety prospective.
Thank you very much for your help in advance.
Shirley
Option 1:
1)     shutdown immediate
2)     copy log files from disk group 1 to disk group2 using RMAN (need to research on this)
3)     startup mount
4)     alter database rename file ….
5)     Open database open
6)     delete the redo files from disk group 1 in ASM (how?)
Option 2:
1)     create a set of redo log groups in disk group 2
2)     drop the redo log groups in disk group 1 when they are inactive and have been archived
3)     delete the redo files associated with those dropped groups from disk group 1 (how?) (According to Oracle menu: when you drop the redo log group the operating system files are not deleted and you need to manually delete those files)
Option 3:
1)     create a set of redo members in disk group 2 for each redo log group in disk group 1
2)     drop the redo log memebers in disk group 1
3)     delete the redo files from disk group 1 associated with the dropped members

Absolutely not, they are not even remotely similar concepts.
OMF: Oracle Managed Files. It is an RDMBS feature, no matter what your storage technology is, Oracle will take care of file naming and location, you only have to define the size of a file, and in the case of a tablespace on an OMF DB Configuration you only need to issue a command similar to this:
CREATE TABLESPACE <TSName>; So the OMF environment creates an autoextensible datafile at the predefined location with 100M by default as its initial size.
On ASM it should only be required to specify '+DGroupName' as the datafile or redo log file argument so it can be fully managed by ASM.
EMC. http://www.emc.com No further commens on it.
~ Madrid
http://hrivera99.blogspot.com

Redo log on disk - do I need to multiplex them?

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