My daily driver had a strange issue, I noticed a squeaky sound couple of times when I would apply breaks. After parking I came out to inspect the source of the noise it was the rear rotor and break pad. Strange part was the rotor was rubbing metal on metal and even though the rotor and pads were less than a year old, it scrapped perfect circle in the top half of the rotor. The lower circle of the rotor surface and pads are perfectly fine. what would cause such irregular wear?
I have ordered new set of rotors , pads and calipers for rear but would like inputs on probable cause?

Could be some poorly manufactured brake pads.
But I'm willing to bet that its because your rear calipers are sticking.
Either the caliper piston is sticking or the slide pins are.

When I did all my brakes a few months ago, I noticed my rear brakes were getting really hot and stinky because the calipers would not fully release. I replaced both rear calipers and now my rear brakes function normally.

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U.S. Army Retired

Agreed... sticky calipers are the likely cause.

Sounds familiar. I replaced rear pads at 40,000 miles and both rear calipers were seized and replaced. Bad batch? Bad design?

The friction material can come off the parking brake shoes and jam up causing heat.

I do not believe the shoes themselves are to blame. I think that the backing plates on rear disc brake designs that have the parking brake drum inside the rear rotor are partly to blame for the drum parking brake reliability issues. They are very thin and are vulnerable to corrosion to the point that they have no strength left; then they tend to fall apart, leaving nothing to anchor the parking brake hardware to. This will cause the parking brake shoes to jam up in the drum, creating tremendous heat while driving and leading the shoes to deteriorate, (friction material coming off, worn out shoes, drums, etc., etc.).