Cooked files and mmap

All Few days ago there was a discussion that lead to comments about using cooked files and taking advantage of the O/S memory management to improve I/O throughput. Surely setting the system up in this way leaves you open to losing information, since online will 'think' that it has written data to disk when it has actually written it to memory which the O/S flushes later. This is the primary reason the manuals recommend raw for critical stuff to ensure that in the event of a failure, online can recover to a known state. Are there new features at the O/S level (such as journalling?) that ensure that this type of scenario does not become a problem with cooked files? Mark MarkDenham@aol.com (home) Denham.M@amstr.com (work)