Re: How to determine the size of cylinder?

From: Mark A. Odell (odellmark_at_hotmail.com)
Date: 11/29/04 

Date: 29 Nov 2004 21:13:21 GMT

linuxquestion@yahoo.com wrote in
news:672ceaed.0411282028.1b8dc772@posting.google.com:

> Dear experts,
>
> I have a good technical question for you.
>
> From the newsgroups:
>
> "From: Gary Boswell (gboswell@dormnet.stu1.uconn.edu)
> Subject: Hard Drive > 500 mb FAQ
>
> Back in ancient times computers had a limitation in the BIOS of the
> following:
> cylinders = 1024
> heads = 16
> sectors = 63
> * 512
> -----------
> or 528,482,304 bytes
> Due to these limitations the maximum size of a hard drive was:
> 528 chkdisk mb
> 503 CMOS mb"
>
>
> My question is:
> - for a given hard drive, how can I tell the size of the cylinder?
>
> In either Redhat, or Windows XP?

You cannot. Modern IDE drives use logical block addressing which masks the
physical layout of the disk from the user. The old CHS method is
maintained for legacy only and only allows you to use a portion of the
drive's capacity. Furthermore, the notion of Cylinder, Head, and Sector
has nothing to do with the physical disk attributes when using the CHS
values provided by the drive.

You may get some information from the disk vendor's OEM Data ***. For
instance, Hitachi sites varying recording zone densities for tracks along
with some other information that should allow you to determine the sectors
per track and then the sectors per cylinder. You will need to do this
off-line calculation for each model and capacity you employ as these
values may (and often do) change. 

-- 
- Mark ->
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