When can I delete these arch1_*.dbf files?

I set up my database for archive mode so that I could do on-line filesystem backups. Now, my filesystem is filling up with files like arch1_6424.dbf. All I can find in my "Oracle8 DBA Handbook" is something to the effect that if I loose these files I'm screwed. Is this true? Can I never delete these files? When is it safe to delete them? I'm using Oracle8i on Solaris 2.7 x86.

Thanks!

John Matzen
Senior Programmer, Ultima Online
Origin Systems, Inc.
http://www.origin.ea.com/ Received on Tue Jun 20 2000 - 00:00:00 CDT