When comparing RAID 5 to RAID 10 I am using the following formulas:

(# of Read Requests + (4 x # of Write Requests)) / # of disks
(# of Read Requests + (2 x # of Write Requests)) / # of disks

In one whitepaper I read to calculate Reads and Writes I should use the following formula. Is this correct?

Physical Reads/transaction = Disk Reads/sec * Transactions/sec
Physical Writes/transaction = Disk Writes/sec * Transactions/sec

I want to make sure I am using the correct Perfmon counters. Are these correct?

TPS = SQL Serveratabases Transactions/Sec (for all databases)
Reads/sec = PhysicalDisk: Disk Reads/Sec
Writes/sec = PhysicalDisk: Disk Writes/Sec

If this is all correct, does that mean Reads/sec is actually Reads/Transaction/Sec and Writes/Sec is actually Writes/Transaction/Sec. If not, I don't see why Transactions/sec (TPS) is used in each formula since TPS consists of both reads and writes.