Obviously archived redo logs are backed up as frequently as required, but does it make any sense to backup online redo logs? Is the online redo log an open and active file such that copying it in this state is a waste of time (same as backing up an open database)?
If the online redo log hasn't switched for 20 minutes (so that the log was available for archiving) then if the system fails and media recovery is required and you haven't backed up the online redo log, surely you've just lost the last 20 minutes of transactions?
I know there are other, more robust ways of transporting redo information to ensure nothing is lost, but I'm still interested in the state of the online redo log files.
Thanks for your time.
Clarifying Update…
There is a regular background process running regularly that ships off archived log files and online log files. I don't have much control of this process. Are the online log files usable, or could they be corrupt if the log was being written to when the backup was taken?
Best Answer
Another thing to consider is a standby database. You can configure that to have the log writer write redo to the listener on a remote system with a standby database (real-time apply). This is done in near real time. The benefit is minimal downtime in the case of a system failure with no recovery needed. Just activate the standby database and go.
The recommendations about mirroring your redo log groups on separate disks are excellent advice. Typically, only one of your log groups is active at a time - the rest are either archived already or waiting for archival. You wouldn't want to copy the active one - it would likely be useless in a recovery scenario.
In short, no you can't copy live redo logs while the db is running and hope to have anything of value when you're done.