dfr wrote:
3. What is where in the last picture of the article? Does it show a surface of one disk or more? If one then what other 3 heads are doing here? In which direction the plate is spinning?
Imaging you reading drive from LBA 0 toward the end
The last picture represent how drive would read actual surfaces when you do linear LBA reading
Hx represent heads. Read lines with arrows (serpents) represent sectors which were read from physical tracks and possible heads movements
You decided to scan let's say Quantum Atlas 10K5 from LBA 0 toward the end. And let's say this drive has 4 heads
Here is how drive is gonna read physical tracks
1. Tracks 0-63 on H0
2. Tracks 0-63 on H1
3. Tracks 0-63 on H2
4. Tracks 0-63 on H3
5. Tracks 64-127 on H0
6. Tracks 64-127 on H1
7. Tracks 64-127 on H2
8. Tracks 64-127 on H3
9. Tracks 128-191 on H0
And so on
If you do the same scan on a Samsung drive it could be something like this
1. Tracks 0-6000 on H0
2. Tracks 0-5900 on H1
2. Tracks 0-6100 on H2
3. Tracks 0-5800 on H3
4. Tracks 6001-12000 on H0
And so on
Each track may have from 1000 to 2500 sectors
Generally Samsungs have a lot more sectors per serpent. This leads to longer seeks when drive needs to switch heads and linear speed drops when drive reads toward OD