HD partitioning and disk position

[Deanodarlo]

It's generally assumed that when you partition a hard drive the first partition will be on the outside of the disk using the lower numbered blocks (say 0-1500) and subsequent partitions will be placed on inner layers of the disk using higher block numbers (>1500).

Using this info, people generally think the first partition will be the fastest while the last defined will be the slowest.

Is this true?

Or can block orientation change for different manufacturers (say block 0 centre or even inside of the platter) and therefore partitions end up in unexpected areas of the hard disk?

Thanks for the help.

 

[Peter]

Desktop drives usually start on the outside tracks, switch through the heads first and then step inward,
giving the typical performance slope (fast on low sector numbers, and decreasing from there).

Notebook drives sometimes follow other schemes, like staying with one head and stepping in first, then
switching to the next head and stepping outward, or something inbetween. This gives some zigzagging
in the performance curve. Why do they do that? Dunno. Maybe switching heads consumes more power than
moving from one track to the next.

regards, Peter

PS: before someone asks, no, HDDs do not use more than one head at a time.

 

[Deanodarlo]

Thanks Peter. Could you please just end by clearing a couple of points up:

1) So what you're saying is the first sectors on the first accessed cylinder (or first sequential blocks in LBA mode) are usually on the outside of the disk on desktop drives and read inwards after relaying heads during sequential reads. This is show by the degrading performance curve in HDTach.

The first partition you set up (using low numbered blocks/sectors in LBA mode) will therefore be on the outside of the platter(s), second a few cylinders in etc. Is this correct?

2) If manufacturers decided to start their numbering at the centre of the disk instead of the outside edge, would this show up on HDtach as a different performance curve?

Also Laptop drives you mentioned - would these display the zig zap performance curve using a program like HDTach?

 

[Peter]

1a) yes
1b) yes
2a) yes it would. You'd see the performance increase from sector 0 upward. Of course this is the most
stupid way to do it (leaving the fastest spot on the drive unused unless it's filled to the brim),
so no drive maker does THAT.2b) Sure.

regards, Peter

 

[Deanodarlo]

^^^much appreciated.