Re: regarding backups

Jeff Kish wrote:

> Regarding backups,
>
> 1. If a database was created with archivelog mode off, can we turn it
> on at a certain point in time to enable better recovery?
>
> 2. What is the best way to create a few extra control files for
> backup/recovery sake? We are using only one for one instance, and two
> for another instance. The two are in the same directory on the same
> disk. I assume ones on different disks are best.
>
> 3. I looked in the following tables to find out what database files
> are critical. How can I be sure of the init****.ora file being used? I
> assume that this file also should be backed up.
> select name from v$datafile
> select member from v$logfile
> select name from v$controlfile

1. Yes - shutdown the database and issue the following commands,

startup mount;
alter database archivelog;
alter database open;

To start the archiver you can either include the line;

log_archive_start = true

in your init.ora or issue the command;

alter system archive log start; -- note this will have to be re-issued each time the db is started

2. The control files are mirrors of each other, so it is best to have at least 2 (I put one on each disk I am using) on separate disks. The best way to create additional ones, would be to copy your existing one and ensure that the new location is specified by the control_files = (.... init.ora parameter. Don't forget to restart the instance for this to take effect.

3. The init.ora file being used will be called init<SID>.ora and must reside in the $ORACLE_HOME/dbs directory. There may also be an ifile parameter in the init.ora which points to another file which may be used during instance startup.
Rather than backing up the controlfile directly I issue the command;

alter database backup controlfile to trace;

which creates a file <SID>_ora_<PID>.trc in your udump directly. This contains the source code required to create a new set of control files and offers a more flexible backup option than merely copying the raw files.

Also, if you are running in archivelog mode don't forget to backup the archives re-do logs.

Hope this helps,

Ian Received on Mon Nov 24 1997 - 00:00:00 CST