archive logs are writen quite frequently by Oracle Process , If you put the log file on the network , the writing is accross the network which is not stable as the harddisk writing . once failed , your database will hang in the middle which means you are in the great trouble . SO far I never heard people doing that .
归档日志备份是备份所有的归档日志还是备份某一时间点以后的归档日志?
You should backup all the archivelog which is generated since your last full backup .