Multiplex Controlfiles in ASM

I have been trying to figure out how to multiplex a controlfile that is in an ASM instance. Normally I would simply shutdown the DB, copy an existing controlfile to my desired location, update the pfile or spfile to the desired location and startup the DB. Since my existing controlfile is in ASM though, I can't do the copy part.
I have tried using RMAN to restore a controlfile, but I can't seem to get the syntax right.
I have seen thread Re: How to multiplexing control files in ASM instance??? however I really don't want to issue a RESETLOGS just to be able to multiplex my existing controlfile. In this thread there is another suggestion without having to issue a RESETLOGS, but this does not seem to get this to work for me. Any suggestions? Thanks.

I found the answer I was looking for. If anyone else had this question, the answer is in metalink document id 345180.1

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Multiplexing Controlfiles in ASM

Hi,
How we can do multiplexing of control files in ASM.
and How we can find free space on disk groups.
Please let me know
thank a lot.

Hi;
Please see below notes which could be helpful for your issue:
How To Move Controlfile To ASM [ID 468458.1] *<< check step 6 and also referance part*
Also see:
ASM Technical Best Practices [ID 265633.1]
Regard
Helios

Duplicating controlfile in ASM

Hello all,
I've just created a 10g stand alone database with just one controlfile. I have just one DG but I want to multiplex it using RMAN copy.
Can someone tell me what are the steps to duplicate the controlfile in ASM?
On controlfile will reside in +DG/<DID>/controlfile and other will be in +DG/<DID>/datafile directories in the same DG.
rman copy from to
alter system set control_files='+DG/<DID>/controlfile/ct1.f','+DG/<DID>/datafile/ct2.f' scope=spfile
Thanks

see the oracle docs :
Performing RMAN Recovery: Advanced Scenarios
"RMAN uses the autobackup format and DBID to determine where to hunt for the control file autobackup. If one is found, RMAN restores the control file to all control file locations listed in the CONTROL_FILES initialization parameter.""

How do I copy a controlfile to ASM

I have a database in which the datafiles are in and ASM instance but two controlfiles are multiplexed to normal ext3 linux filesystems.
How do I copy the controlfile to ASM to multiplex the controlfile there too ? Can I use rman convert to do this ?
Regs
johnnie d

if your disk group is data1, then set control_file='data/control01.ctl' in init.ora file
startup nomount your database using init.ora file
RMAN>connect target;
RMAN>restore controlfile from '<your_location>';
RMAN>alter database mount;
RMAN>alter database open;
Seec metalink doc id 252219.1
Thanks.

Multiplexing controlfiles

Hi All,
I have recently completed migration of Database from OCFS to ASM. I have started the database with one controlfile. Now i want to create another 2 copied of controlfiles. As far as i know in normal filesystem's case the steps to accomplish this will be
1. Bringdown database
2. Create copied of controlfiles using cp command.
3. Change control_files parameter in initfile.
4. bringup the database using initfile.
But incase of ASM i am not sure how i can copy control files, i tries using RMAN but i am getting errors that the second controlfile is not in sync with the first/original one. I do really appreciate any help you can provide regarding this.
Thanks,
Aditya.

1. Shutdown the database and start the instance:
SQL> shutdown normal
SQL> startup nomount
2. Use RMAN to duplicate the controlfile:
$ rman nocatalog
RMAN>connect target
RMAN>restore controlfile to '<DISKGROUP_NAME>' from '<OLD_PATH>';
3. On the ASM instance, identify the name of the controlfile:
Using ASMCMD:
$ asmcmd
ASMCMD> cd <DISKGROUP_NAME>
ASMCMD> find -t controlfile . *
alter system set control_files='newone', old one' scope=spfile;
shutdown immediate
startup.
How to duplicate a controlfile when ASM is involved Note:345180.1

How can I add a new controlfile in ASM?

In the ASM,I can't copy any file.How Can I create a new online controlfile? Thanks!

You can use "alter database backup controlfile to trace" command to get the control file contents.
Now you can use create controlfile:
1) If you use resetlogs, use file creation context form for specification of log files.
2) If you use resetlogs, use file reference context.
Why do you want to create a new control file. Is it for multiplexing purpose?
Reference: Chapter-12 of Oracle database administrator guide 10gR2
search for title "Creating a Control File in ASM" ...
Hope this will help you.
Regards,
Neeraj

Mutliplexing controlfile on asm - asmcmd cp not working

Attempting to multiplex a controlfile on new database I have setup in 11.1.0.6 on ASM.
Existing control file in +DATA diskgroup in asm
Steps as follows:
alter system set control_files
= '+DATA/abc11g/controlfile/current.260.660240667'
, '+FLASH/abc11g/controlfile/current_controlfile_backup'
scope=spfile;
shutdown database,
copy one of controlfile to new locations in +FLASH using cp command in asmcmd
startup database.
Error message as follows:
ORA-00205: error in identifying control file
I alert file I found:
ORA-00227: corrupt block detected in control file: (block 1, # blocks 1)
ORA-00202: control file: '+FLASH/abc11g/controlfile/current_controlfile_backup'
ORA-205 signalled during: ALTER DATABASE MOUNT...
It appears the cp command in asmcmd does not work correctly, even though the file is physically there - or am I doing something else wrong?

Just out of curiosity, what's the exact reason you want to multiplex control files? You already have redundancy at ASM and/or disk subsystem level, and you can have RMAN to keep an up-to-date autobackup of controlfile for you in +FLASH diskgroup.

Controlfile on ASM performance question

Seeing Controlfile Enqueue performance spikes, consideration are to move control file to separater diskgroup(need outage) ? or add some disk(from different luns,( i prefer this approach) in the same disk group , seems like slow disk is casing this issue...
2nd question :can snapshot controlfile be placed on ASM storage?

Following points may help:
- Separating the control file to another diskgroup may make things even worse in case that the total number of disks are insufficient in the new disk group.
- Those control file contention issues are usually nothing to do with the storage throughput you have but the number of operations requiring different levels of exclusion on the control files.
- Since multiple copies of controlfiles are updated concurrently a possible, sometimes, problem is that the secondary copy of controlfile is slower than the other. Please check that this is not the issue (different tiers of storage may cause such problems)
Regards,
Husnu Sensoy

How to multiplex controlfile ?

Guys,
I currently have a RAC database and it has two copies of controlfiles sitting in ORADATA and ORARECO diskgroups. I need to create another copy in ORAREDO.
We use RMAN.
How do i go about the procedure.. I will be doing this on production, so please make sure you give the right steps..
I looked at the metalink doc but it wasn't very helpful.
Also, i need to name the third controlfile to a specific name.. Like backup.445.345343
Thanks
G

Note:345180.1 goes into detail on this process. Not sure what else can be suggested beyond following this note's directions.

Does the controlfile need to be multiplexed in ASM?

OS=Linux 5
Oracle=11gR2 RAC with ASM
We have two diskgroup (DATA, FRA), each with 6 disks. The controlfile currently resides on the DATA diskgroup. My question is, does the controlfile need to be multiplex to FRA diskgroup in case of a diskgroup failer? Typically if the database is using filesystem for storage, i would multiplex the controlfiles to 3 different filesystems.

Hi,
This thread already been answered but I'll leave a little touch.
Some time ago we used OS filesystem to store database and we placed a part of the database at each mount point (like /u01, /u02, /u03 and so on).So, we also multiplexed control file to due flexibility of recover a controlfile if any error occurs on one theses mount points.
But with ASM generally the whole database is placed on Diskgroup DATA and controlfile on DATA and FRA and if you lose your diskgroup DATA and this will not change anything in relation to high availability, because you will need to restore database to bring database up. So, If you have backup of database of course you also have backup of controlfile.
About multiplexing de REDO in other Diskgroup can make all difference. If you lose diskgroup +DATA and you have your archivelog and redo online avaliable on other diskgroup you will have a minimun or none lost of data.
I don't like multiplex controlfile on FRA, because any maintenance that involves diskgroup that have controlfile stored will cause downtime of database. So, when I multiplex controlfile I choose diskgroup that have datafiles only of that database.
Redo and Archivelog we can change they of diskgroup without downtime of database.
As FRA is a Diskgroup used to store backup and Archivelog can be exausted and it can cause downtime on database. (We must not forget we can control it)
Other point:
In some env I have seen DBAs configuring Normal Redundancy to Diskgroup (e.g DATA) that store database and External Redundancy to Diskgroup FRA (e.g FRA) due purpose of that Diskgroup. By Default DBCA place controlfile on FRA, so If by any reason asmdisk from FRA fail, the whole database will down due controlfile on that diskgroup. This is a big mistake.
*Unable To Open Database Due To Diskgroup Used To Multiplex The RedoLogs & Controlfiles & Archivelogs Got Corrupted. [ID 1382372.1]*
Regards,
Levi Pereira

ASM Environment multiplexed redo logs

When we have multi diskgroups like ('+DATA','+FLASH) and configured to multiplexed redologs on asm environment what would be the performance impact while logwriter writing on multiple locations? The diskgroups have different number disks on each diskgroup. Like 100 vs 10 disks on diskgroup.

http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm
Multiplexing Redo Log Files help protect against a failure involving the redo log itself.
after you implement, you should check AWR report about waiting.
On ASM, you don't need to make multiple redo files. Just place it (redo file) in good i/o diskgroup (RAID1/0)

Duplicate standby asm controlfile parameter

Hi
I want to create a standby database by using duplicate standby command.
Both primary and standby databases are on asm.
How should I set controlfile parameter in standby database spfile before initiating duplicate for standby clause ?
Primary:
SQL> show parameter control
NAME TYPE VALUE
control_files string +DATA/orcl/controlfile/current.260.769439087Should I set the same controlfile parameter for standby spfile or should I just set "+DATA" ?
I tried setting just "+DATA", however during duplicate, the instance couldnt create a controlfile in ASM.

http://docs.oracle.com/cd/E11882_01/server.112/e25608/scenarios.htm#SBYDB4897 says:
>
If the primary database is configured to use OMF, then Oracle recommends that the standby database be configured to use OMF, too. To do this, set the DB_CREATE_FILE_DEST and DB_CREATE_ONLINE_LOG_DEST_n initialization parameters to appropriate values. Maintenance and future role transitions are simplified if the same disk group names are used for both the primary and standby databases.
>
So try to not set CONTROL_FILES parameter and set only DB_CREATE_FILE_DEST parameter:
DB_CREATE_FILE_DEST='+DATA';

Question about ASM

Hi dears,
I am planning the installation of G.I 11R2 and have a question regarding ASM.
If I have ASM diskgroup with normal or high redundancy for my DB need I create multiplex redologs and
multiplex controlfiles ? If I understood correctly the multiplex redologs and controlfile is another HA and DR option.
From Oracle documentation
*"To protect against a failure involving the redo log itself, Oracle Database allows a multiplexed redo log, meaning that two or more identical copies of the redo log can be automatically maintained in separate locations."*
Question rised when I checked my old G.I with RACcheck and got the following....
The online redo logs of an Oracle database are critical to availability and recoverability and should always be multiplexed even in cases where fault tolerance is provided at the storage level.
The controlfile of an Oracle database is critical to availability and recoverability and should always be multiplexed even in cases where fault tolerance is provided at the storage level.
"should always be multiplexed even in cases where fault tolerance is provided at the storage level"
WHY ????
Please share your experience.
./thanks

Ilmar Kerm wrote:
Redo logs and controlfile are very critical for database, and if something happened with one copy of them (like file is deleted or corrupted) you can quickly recover by copying over the damaged file with the contents from the surviving file (copies are identical). So copies should be located on separate LUNs/disks/diskgroups/filesystems.Thanks Ilmar for reply.
I understand what you said its obvious. My questions is that if I already have 2 copies or 3 copies of redolog files with ASM nigh or normal redundancy why I need to do it also with creating multiplex redo file.....

Control file multiplexed RAID question

2 node RAC. OEL 5. 11.2.0.2
Is there any cause for concern over design issues when placing multiplexed controlfiles on disks with different RAID types?
I have FRA, REDO, VOTE and DATA disk groups available to me DATA is RAID 5, the rest are RAID 10. Is there any tales from the field of write speed issues multiplexing the files on a RAID 5 and a RAID 10?
Edited by: 961469 on Dec 11, 2012 6:10 AM
edited to include versions and env

Is there any cause for concern over design issues when placing multiplexed controlfiles on disks with different RAID types?IMHO, I believe not. Of course this depend on characteristic of I/O of each Array.
As best practice never mix files stored on array with heavy I/O with array which has Low I/O.
Controlfile is good for RAID 5 and RAID 10 no worry.
Read note:
I/O Tuning with Different RAID Configurations [ID 30286.1]
Swap space can be used on RAID devices without affecting Oracle.
====================================================================================
RAID Type of RAID        Control       Database        Redo Log        Archive Log
                            File          File            File            File
====================================================================================
0     Striping             Avoid          OK           Avoid           Avoid
1     Shadowing             OK             OK          Recommended       Recommended
0+1   Striping +            OK         Recommended       OK            Avoid
      Shadowing
3     Striping with         OK           Avoid           Avoid            Avoid
      Static Parity
5     Striping with         OK           Avoid           Avoid            Avoid
      Rotating Parity
------------------------------------------------------------------------------------On this case the main concern is:
Something which should help can disrupt and cause downtime.
Unable To Open Database Due To Diskgroup Used To Multiplex The RedoLogs & Controlfiles & Archivelogs Got Corrupted. [ID 1382372.1]
Regards,
Levi Pereira

Creating two controlfiles in an auxiliary init.ora file

How can two controlfiles be created in an auxiliary init.ora file ?

for asm you can connect as asmcmd (change ORACLE_SID/HOME first) and copy controlfile (don'r forget, shutdown, modified init.ora, and startup with init.ora):
ASMCMD> cp <controlfile at disk> <controlfile at asm>
i.e.:
ASMCMD> cp '/tmp/control01.ctl' '+DATA/controlfile/control01.ctl';
ASMCMD File Management Commands
more about asm --> Contents
if you are new into oracle, you should read this first --> Contents

Multiplex Controlfiles in ASM

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