We run our oracle hot and cold backup scripts a couple of hours before amanda starts to dump the servers. We copy the backup (oracle cold and hot backup files I mean) to a particular (BIG) disk on each server and amanda only backups this disk (we use exclude lists on the oracle datafiles mount points to prevent amanda from backuing up "live" datafiles and double backing up oracle)

It's real easy this way.

If you use RMAN, you can create a channel to disk and do something like that.

The key point here, is to use exclude list to prevent backing up live oracle files, and use some wrapper script around amdump to make sure that the oracle backups completed OK on each RDBMS server before starting to dump it.