Undo Table Spaces

Hi

We have a disk based backup solution that trickles changes over the internet to a remote backup server. The problem we are having is the amount of data change in the Undo Tablespaces. This in turn means large data being sent over the internet to the remote backup server.
Do we need to backup these undo table spaces (UNDOTBS1 datafiles) for a successful database recovery ? From what I read, these are UNDO table spaces that are a new addition to Oracle9i. Can I omit these files from daily backups and have it recreated when recovering the database ?Let me know your thoughts. Thanks !

UNDO segments are required when you recover a database.

What tool are you using to sending the changes?. Is it file based solution which sends change OS level block to remote site?

Unless the tool is certified for Oracle, I would not trust such method of backup.

Have you ever tried to recover from the backups in remote site?

I am using Oracle Agent for Arcserve to backup the databases to disk. Then another backup agent backs up the file based Oracle Arcserve Agent dumpfiles to a local backup server. This server then sends the changes to a remote backup server. Only the daily data change is trickled over the wire. But the undo tables spaces have a lot of change which in turn means a lot of data has to be sent over the link because of the undo files. I was thinking whether I can get away with not backing up the UNDOTBS1 data files.