Hi,

If this is a production database then it should definatly be in archivelog mode. I have an OLTP system runnig 8.1.7 on solaris 2.8 and it runs in archive log mode. There has not been a great impact on performance. Having said this it all depends on your specific database setup e.g. datafile configuration, disk layout etc. In general as long as the LGWR & ARC0 processes
are not experiencing contention and you have enough online redo logs
you should be ok. The only way to really find out is to implement archive log mode
and see what happens. You can then correct any araes that experiance a performance hit.

hope this helps

shaz