i search for a methode to save redologs online via network.
How can i made it without close the database. And how can I rebuild the database after a disaster? And which files i must have absolutly to
redo after disaster.
In general you don't want to backup the online redo logs. The reason being is that if you accidentally overwrite the current online redo logs with older copies from your backup then you can't do a complete recovery. To safeguard against problems with your online redo logs you want to be sure and have multiple members in each redo log group and have the members on separate drives. RMAN deliberately won't backup online redo logs specifically because of this possibility.
That being said, if you really do want to backup your redo logs the only way to do so reliably is with a cold backup, ie, with the database shutdown.