Preclear read times changing

[tucansam]

Not a show stopper but more of a point of curiosity for me.  In just shy of 48 hours I will have precleared a 4TB disk.  When I started, I was getting 108MB/s.  Now I'm at 80MB/s (a few hours ago I was at 96MB/s). 

 

Is the slower speed because the heads are running on the very edge of the platters, where they are physically spinning slower?

 

 

[JonathanM]

Not a show stopper but more of a point of curiosity for me.  In just shy of 48 hours I will have precleared a 4TB disk.  When I started, I was getting 108MB/s.  Now I'm at 80MB/s (a few hours ago I was at 96MB/s). 

 

Is the slower speed because the heads are running on the very edge of the platters, where they are physically spinning slower?

Yes, at the very center of a CAV disk, the sectors pass under the disk that much slower. It's spinning at the same rate, but less material passes the heads per revolution. It's set up like an old LP, reading from the outside in and keeping the same RPM throughout, instead of the original CD specs, that reads from the inside out, and slows down the spin to keep the linear velocity the same.

[tucansam]

Awesome.  Learn something every day.  Thanks.