How to use non most recent backup to do recovery?

I just started to do some backup/recovery testing. I used the same one channel and all backup sets went to the same directory. It seems that Oracle select the most recent backup by default when do recovery. My question is: How can I use the old backup which is not the most recent backup to do recovery?

Another question is, usually how many channels do people use for regular backup activities like weekly entire database backup and full tablespace backup, daily incremental tablespace backup, etc ?

Thanks for any help.

For your first question: It all depends how much recent data you want to recover to. Depends on that you will select how old the Backup should be used.

Your Question: It also depends on, your business requirement, typically, Hot backup taken every day, cold backup and export every week.

For first question, you need to supply the time you want to recover to. For example:

run {
set until time '24-APR-2001:09:00:00';
allocate channel ch1 type disk;
allocate channel ch2 type disk;
restore database;
recover database;
};

Second question:
I usually use two channels. I see some others use up to 7 channels. I think it all depends on your system resource. hope it helps


Dragon

Thanks for reply.

My question might not be very clear. What I really want to know is how I select a particular backup to do recovery. For example, I have two full tablespace backups -- backup1 and backup2. The backup2 is the most recent one but got removed accidentally, so I need to use backup1 to do recovery. However, I got the error ORA-19505: failed to identify file "......". It seems that Oracle always try to find the most recent backup. Is there any way to define to use the non most recent backup, in this example to use backup1 to do recovery?

You can use any backup taken down the road as long as it is not corrupted. in other words it is taken correctly. In your case, you can use old backup Backup1 and recover by applying all archive logs to make it current.

But it seems, even your backup1 is not taken correctly. So it shows so and so datafile is not identified. Other wise check your controlfile text and see the path and every thing is specified correctly

But how can tell Oracle to use the backup1? The error showed "failed to identify the file of backup2".

My backup1 seems OK as I did use it to do recovery successfully before I did backup2.

Wipe out all the files contolfiles, datafiles. Then, copy all of them from Backup1. Then create the controlfile which is copied to text. Then it should work. Presently your controlfile is pointing to Backup to files.

I never try it but I think you need
"set until time xxx" (which is prior to backup2) to force rman use backup1

For Rman, unless you specify a time, it will always use your latest backupsets. If you specify a time, it will use the backupsets latest to the time your specify. Then apply all the logs you have from there to the point you want it to recover.

Dragon