I am trying to figure out the best number of disks I need to include in a RAID5 configuration so that I can get the bandwidth that the application needs. Problem is that disk transfer rates are very confusing. While the Sustained Transfer rates for the disk is about 40 MB\sec as per specs, the SAN expert I was talking to said the disk will not give more than 15 MB\sec, while the disk manufacturer says it is capable of doing this.
Is there any site or paper that can give realistic bandwidth or give a formula to calculate it. I have 15K 73.4 FC, 10K 73.4 FC and 10K 146.8 FC disks.