The usage notes for ARCHIVE LOG currently state that using this command will cause a database to lose a portion of its log sequence number (LSN) space, and thereby hasten the exhaustion of valid LSNs. To put this space usage into context, if you have a log file size of 100MB and run ARCHIVE LOG every five minutes, it will still take approximately 40 years to exhaust the valid LSNs. Under most operating conditions, you will not experience an impact.