As the topic states I am wondering if there is a resource with this information. I was attempting to read the WD drive specs from their website but didn't see anything jump out at me. I now have 4 WD drives:

3TB RED

4TB Green x2

5TB Blue

 

I was curious to see if they all had 1TB platters or if a few had larger?

Afaik only the 6TB has larger platters, good info here:

 

http://rml527.blogspot.pt/2010/09/hdd-platter-capacity-database.html

Very nice, glad I asked! Looks like all mine have a 1TB platter so that should mean that all the inner platter slow downs happen at the same time turned a parity check correct?

The same capacity disks will slow down at same time, but because you have 3 different sizes your parity check will look similar to this:

Why wouldn't there also be big dips between the 1 & 2 TB marks? Ps your graph is very nice, it makes me happy.

That would only happen if you also had 1 or 2TB disks, the 3TB has 3 x 1TB platters, they are read simultaneously from the outer (faster cylinders) to the inner (slower) cylinders, so when the 3TB disks are near the end they slow down to their slowest speed, but the 4TB disk is on the 75% position of its 4 platters, so the speed goes up when the 3TB disks are over, same thing when the 4TB ends and only the 5TB remains.

 

Hope it makes sense, if not maybe someone can explain better as English is not my first language.

Oh that does make sense, I didn't know that all the patters went from outer to inner at the same time. I always thought they went outer to inner for each patter and then started back over but that would not be very efficient. Thank you.