Oracle 10gR2, Win2003.
I know enough about RMAN to perform basic functions. I'm trying to learn more.
We have an RMAN backup process that is used to duplicate a database nightly. The backup is generated on a single disk. The script allocates 2 channels for that backup, both pointing to the same directory. It works fine, generating 2 backupsets (backupsets? I think. I'm a bit confused about terminology: a backup consists of one or more backupsets?). Anyway, the duplicate process picks up these backupsets and restores a copy of the database from them. I noticed today that it allocates 3 channels, but only two appear to be used. Is that because the backup process only used 2? Which brings me to the major point: given my configuration, is there any advantage to allocating more channels for backup and restore? This is an 80GB database, and the restores takes over 2 hours to complete which seems slow to me - I can do a hot backup in that amount of time, and I thought RMAN had performance advantages over simple scripted backups.
To summarize my questions:
- Does an RMAN backup consist of one or more backupsets?
- Can a restore operation only use as many channels as were used in the backup?
- Is there any advantage to increasing the number of channels for both given a backup to a single disk?