Not to nitpick, but you'd be better off putting the tablespaces into
backup mode one at a time in your shell script, because Oracle has to do
additional (larger) logging when a tablespace is in backup mode.
Basically it has to log OS block images instead of DB page or data
images.  Anyway, if you happen to hit a period when a tablespace is
backup mode and someone is loading into it, you can generate a terrific
amount of redo log.  So rather than put all your tablespaces into backup
mode at once, it's better to have your shell script do something like
this pseudo-code:

For each tablespace t {
   put t into backup mode;
   backup t using OS commands;
   take t out of backup mode;
   }
backup your archive logs, pfiles, spfiles, pwfiles, etc.;

RMAN is a great help with hot database backups as well as the
incremental copies that have already been mentioned, by the way.
Regardless of whether you use RMAN, though, hot backups will require
that the database be run in ARCHIVELOG mode (shutdown immediate; startup
mount; alter database archivelog; alter database open;) and that means
that you need to set up archive log backups also.

Hope this helps,
Chris

| Date:    Mon, 28 Mar 2005 17:12:16 +0100
| From:    Andreas Almroth <almrot_a AT MTNCAMEROON DOT NET>
| Subject: Re: Backing up a 150GB Oracle DB on a datawarehouse server
| 
| Luc Beaudoin wrote:
| 
| >Hi all
| >
| >I have to take a new Oracle server (AIX), it's our new Datawarehouse
| >server ....
| >
| >I know that I have to stop the Oracle DB before the backup 
| and restart it
| >after. ..
| >
| >
| Well, you really don't need to take if offline at all, 
| depending on how
| much work you are willing to spend on configuring the backup.
| Most of the DWH systems I have worked on had to be up at all time, as
| they constantly processed new inputs from other systems, so you would
| probably need to do hot backups. Unless you can have a backup window
| that is.
| 
| >My question is .. the DB has to be up and running as fast as 
| it could ...
| >so what should be the best way to take that Oracle DB in 
| backup (incr,
| >image, snapshot or ???)
| >
| >
| If you have the TDP for Oracle, it is easy, use Oracle RMAN 
| to do online
| incremental 0 and 1 backups, with archive logs. The database 
| will never
| have to be taken offline.
| 
| If you don't have TDP, well then you can do the good ole' 
| Oracle backup
| using some shell scripting. Essentially you would use a 
| prebackup script
| to put all tablespaces in backup mode, then backup all files 
| and archive
| log files, and the postbackup script would put all tablespaces back in
| normal mode.
| 
| Regardless of method you will not have to take the database offline.
| 
| /A
|