Oracle® DBA Guide to Data Warehousing and Star Schemas

The Raw vs. Cooked Files Debate

Another question that often arises is whether to use raw or cooked files. The answer here is very simple: Use cooked files. The only time to use raw files is for OPS as it is a key requirement.

Raw files offer two performance improvements: asynchronous I/O and no double-caching (i.e., caching of data in Oracle SGA and UNIX file system cache). Quite often, the realized performance gain is relatively small. Some sources say 5–10%, while others wildly claim 50%. There really is no universal consensus on what the real performance gains are for using raw files. However, nearly everyone agrees that raw generally requires more skilled and well-trained administrative staff because none of the standard UNIX file system ...