Oracle Database Discussions

HI im using oracle 11g r2,

could someone please give me a kick start with the following..

I want to measure the time taken to write to a HDD and SSD drive,...

to do this im using the linux dd command and capturing the times to write a single 4k block to each drive..

what considerations should I be making in terms of the database? should the block size that oracle uses be the same as the block size I am testing the devices write speeds with?

i.e if oracle uses a bock size of 4k ... then I will test the time it takes to write 4k blocks to each disk?

if that makes sense? or is it irrelevant?