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This is generally why your group size and OS page size should be the same (yes, I know...unless you have some kind of giant records, or dynamic files, or any of the other "YaBut's").
> So...this school of thought says that modulo 1 is a good thing, and > that it forces files into memory. The question is -- is the school of > thought speculation, or is it true?
Whether to size files to OS page sizes or size the file to whatever guide says is one of those subjects that we should invest some solid benchmarking in as comments for and against seem to come up from time to time. I have a vague recollection Stephen O'Neill at IBM has posted on this but I'll need more coffee to say for sure. My limited understanding is... If the file group is bigger than the page size then the OS will need multiple reads to read it. However, Linux (and I presume any modern OS release) do predictive read-ahead and if you have a SAN, it should also be doing the same thing. Factor in the buffering also going on in the OS and SAN and the answer is less clear. While multiple read requests may go out for the file group, if it is in an OS or SAN buffer it will be coming back fast. So on a properly spec'ed machine, sizing the files according to guide and leaving the OS to do its job is the best course of action? Correction or comments welcome. Regards, Adrian ------- u2-users mailing list [email protected] To unsubscribe please visit http://listserver.u2ug.org/
