HDDs disks/speed dependency

Question

Is there a dependency in how many magnetic disks from speed? I mean is it faster if hdd has 3 magnetic disks or 2 ? :)

Answer 1

platters? fewer platters means less need to seek i think. This seems relevant too

Answer 2

I believe that the number of platters is not an indication of the disk speed.
This article lists the following factors:

1. Rotational speed
2. Mechanical latencies
3. Disk transfer rate

where I believe rotation is probably the most important factor for random seek.

Answer 3

Drives with Higher densities are faster because more data moves under the read/write heads in any given amount of time. Seek time is a wash since the RPM and speed that the head moves in/out is essentially constant between drives within a class. Within a single capacity level newer drives with fewer high density platters will be faster than older ones with more platters. More platters will only help if you're doing the equivalent of short stroking the drive. Seek times for 100GB of data on a 2 platter 3.5" 1GB drive will be lower than on 1 platter 500GB model because the heads won't have to move as far. The higher transfer times will let the 2 platter 1GB drive beat an older 3-5 platter 1GB model.

That said, Stefan is right about SSDs being the way to go when speed really matters. A good SSD will blow even the fastest harddrive out of the water.

Answer 4

More platters should mean lower seek times since the arm needs to move a shorter distance. Sequential reads/writes should be faster on one with fewer platters. It would, however, be hard to even find out how many platters a certain drive contains. It's also not a good indicator of performance since it affects some things and not even those in the same direction, base your choice on real-world benchmarks instead, there are plenty out there.

Anyhow, if performance is a big issue, nowadays, you don't buy magnetic disks, you buy SSD-drives. The random reads and writes, which is the more common usage in desktop machines, is much faster on those.