Our organization utilizes inexpensive commodity hardware where the trade-off for less durability is compensated by running more standbys. This reduced our costs overall while ensuring a more robust testing and disaster recovery environment. Along with the fact that certain DATA GUARD configurations can also run in a mixed oracle binary environment – 64-bit and 32-bit but on the same operating system family. You can mix hardware from different manufacturers, number of CPU’s, RAM and storage, processor and operating systems versions and distributions providing even more flexibility in designing the architecture. (See Metalink Note:413484.1) There are some major issues with working in a mixed environment- lack of good documentation, RMAN may not be usable and more errors during switchover/failovers. Note: DATA GUARD cannot be used, only the SQLPLUS command line for mixed environments in 10gR2, this limitation is removed as of 11g. Also note in a mixture of 32 and 64 bit environments that an extra step has to be done before switching over, see Metalink Note:62290.1 Changing between 32-bit and 64-bit Word Sizes.
Personally I wouldn’t recommend a mixed environment for failing over a production database but would certainly be suitable for testing or development reasons.
Local Site- Different Building, Same City Block, Different Subnet , RTO* – 30 minutes, No data loss Logical Standby – Reporting only
Remote Site – 80 miles away, Different IP, Exterior DNS, VPN Tunnel, RTO* – 24 hours, SAME HARDWARE as production, No data loss, Logical Standby data already duplicated
*RTO – Recovery Time Objective (how long can you be down?)