I am trying to understand some basics in the I/O area. What I want to know is when people talk about disk I/O speeds on a standard HDD, are the speeds mentioned taken at a physical disk level or based on logical partitions? The reason I am asking this is also because many places where I researched, the question is asked about disk, especially with linux, and in the results or answers people usually refer the mount points that exist in the system and both parties are in consensus. I feel, the terms disk and partitions are used interchangeably which is what confuses me.
I am using some distributed applications for which the disk I/O speeds are vital. Right now, I have one single physical disk with multiple mount points on the same. So here, if the disk I/O max capacity is say 70 MB/s, does it mean that all mounts put together, I can only get upto 70 MB/s (meaning the speed is physical disk not partition based) even if the application can push more data in parallel to multiple mount points faster than that or can I get each partition to max out at 70 MB/s? I am inclined towards thinking that it is physical disk based. I just need some additional validation and maybe some material where I can gain some more knowledge regarding this topic. If it is disk based, I am considering adding more disks so that the application can get some extra speed.