failure of storage containing another copy of oracle redo and archive logs

[Eric Antunes]

Yes,

There are 2 good Oracle tech sites I know:

Metalink (http://metalink.oracle.com)

Oracle Technology Network (http://www.oracle.com/technology/index.html)

In Metalink you must be registered.

There is this doc. in the OTN:

http://www.oracle.com/technology/deploy/availability/pdf/MAA_WP.pdf (search with multiplex in it)

Best Regards,

Eric Antunes

[Eric Antunes]

Hi again,

To create new redolog members are in the Generic Documentation CD that comes with Oracle Database or here:

http://www.oracle.com/technology/documentation/oracle8i.html (Or http://www.oracle.com/technology/documentation/oracle9i.html, etc...) and download the Administrator Guide for HP-UX.

To multiplex the control files:

1º - Shutdown database

2º - Copy one of the existant control files to the new location

3º - Give it a different name than others

4º - Include it in init.ora file like this:

control_files = /disc1/oradata/TST/cntrl01.ctl,
/disc2/app/oracle/TST/cntrl02.ctl

Best Regards,

Eric Antunes

[Yogeeraj_1]

hi jawed,

allow me to add this too!

To create a multiplex redo log files environment, you simply create groups with more then 1 member in them.

E.g.
system@ORA9i.mu> alter database add logfile
group 5 ( '/u02/oradata/ora9i/redo05.log',
'/u04/oradata/ora9i/redo05.log' )
size 10m;

Database altered.

The above sql command added a group with 2 members. Thus, they are now multiplexed. You can just add members to existing groups as well.

MOST IMPORTANT:
Make sure the members of the groups are on DIFFERENT physical devices -- because of otherwise, you would be defeating the purpose of multiplexing them in the first place (recovery from media failure)

hope this helps too!

kind regards
yogeeraj

[Yogeeraj_1]

hi again,

another useful link:
http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c04space.htm#10193

regards
yogeeraj

[Jawed Akhtar]

Hi Yogeeraj,
Yes we did multiplexing of redo logs by putting them on differnet physical device. Even these physical devices are in different storage arrays.
What I wanted to assure that in case of failure of one copy of redo log file the data base will not hang.

Thanks

[Volker Borowski]

Hi,

first of all: If you want to feel safe, test it yourself. So get yourself a testbox, install a second database just for you and may be your dba. Get a testversion for a windows-pc if nothing else is available, but you need to DO this kind of action, just to feel safe when it comes to the point where you HAVE to do it.

Kick away a redolog member and watch the alertlog what happens while you force logswitches. Bounce the DB while the log is defective. Replace the member with a valid one... Lot of things to find out, just to be confident you can handle it when it happens in production.

Allthough I did not a complete test since 8.0 I had some real defectives to fix in 8.1 and 9.2 and here goes....

Losing a redolog member will let the DB stay up and running. Been there, done that.

I only lost a controlfilecopy (one of three) once and that did crash the instance.
Startup was impossible until I replaced the defective copy (I mind to remember that this was on release 8.0). I did not try to train that error out for some releases, so may be 9.x is doing diffrent.
But I'll try this on my testdb next week, seems to be something that one should test once in a while :-)

Volker