The Cost of High Availability (HA) With Oracle
Active Data Guard can be used if the locations are far apart, while Oracle RAC promises transparent application failover if they are in close proximity. For Enterprise-class users with database heterogeneity, then GoldenGate software, the 2009 addition to Oracle's portfolio, is an attractive solution. And for those with no stringent real-time I/O requirements, backup might be enough, so it's worth considering Oracle Secure Backup or the external cloud variants that allows to save on CapEx. With this option, there's no need for extra hardware if the data is on the cloud. Home-made solutions based on Streams are also not unheard of.