Dbwr_io_slaves???

My question is a simple one, no where can I find an answer to this question. When using dwbr_io_slaves oracle default is 0, and range of accepted values is 0 to system-dependent value. How would one find out the system-dependent value? I have seen i/o slaves = to number of hard disks, but in a larger system they have multiple disk but only 4-8 controllers, so then do you set it i/o slaves = to number of controllers? I have researched this topic on many forums and also on metalink ( oracle support site ) and havent seen anything posted as a recommendation.


--also I appologize for any misspelled or illogical phrases in the open paragraph ( if you can even call it that )

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