Dear experts,

I have a good technical question for you.

From the newsgroups:

"From: Gary Boswell ((E-Mail Removed))
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?

Thanks

Pi*R^2*H

For computers, see Google
hard drive cylinders ... diving cylinders scuba cylinders
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cylinders cng india cng nec hard drive cylinders wax
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2

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
| Dear experts,
|
| I have a good technical question for you.
|
| From the newsgroups:
|
| "From: Gary Boswell ((E-Mail Removed))
| 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?
|
| Thanks

(E-Mail Removed) wrote:

> Dear experts,
>
> I have a good technical question for you.
>
> From the newsgroups:
>
> "From: Gary Boswell ((E-Mail Removed))
> 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?
>
> Thanks

All but ancient HDs use ZBR, which means that the number of sectors on
a cylinder varies. Outer cylinders have more sectors than inner ones.
--
Cheers, Bob

The sure way is to fire up the browser and then look up the specs for
the drive in question on the manufacturers web site.

Bob Willard wrote:

> (E-Mail Removed) wrote:
>
>> Dear experts,
>>
>> I have a good technical question for you.
>> From the newsgroups:
>>
>> "From: Gary Boswell ((E-Mail Removed))
>> 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?
>>
>> Thanks
>
>
> All but ancient HDs use ZBR, which means that the number of sectors on
> a cylinder varies. Outer cylinders have more sectors than inner ones.

Bob I wrote:
> The sure way is to fire up the browser and then look up the specs for
> the drive in question on the manufacturers web site.
>

I wish it were true, Bob I, but major HD vendors no longer publish detailed
specs online. The cursory specs tell you how many usable sectors a HD
has, but not the ZBR table of sectors/cylinder vs. cylinder.

If you know where to get those details from WDC and Seagate for current SATA
and PATA HDs, I'd be rather interested.
--
Cheers, Bob

Bob I wrote:
> The sure way is to fire up the browser and then look up the specs for
> the drive in question on the manufacturers web site.
>
What an interesting idea!

However, Maxtor do not tell me the number of cylinder size or the number
of cylinders on my four KU018L2 hard drives. They tell me the drives have
one disk with two heads and two recording surfaces. That there are 512
bytes per sector. Other models have 2 or 4 disks, so 4 or 8 recording
surfaces. (With my two 6Y080P0 drives, they tell me that they have 512
bytes per block, and it is logically CHS 16383/16/63, but I do not know
what that really means since they have models from 60GBytes to 200GBytes
with the same specification of logical CHS. They obviously do not take the
CHS specification very seriously.)

So clearly a cylinder has two tracks, if that is what you mean by cylinder
size. The other models have 4 track or 8 track cylinders.

But so what? How many sectors are on a track? That very clearly varies. If
I try to read an entire drive; e.g., running badblocks in verbose mode on
it, I can see that it slows down from around 57 Megabytes/second at the
outside edge to about 31 Megabytes/second at the center. So clearly the
number of sectors/track is not constant, but monotonically decreasing.

--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 15:45:00 up 37 days, 18:40, 3 users, load average: 4.11, 4.15, 4.10

(E-Mail Removed) wrote in
news:(E-Mail Removed):

> Dear experts,
>
> I have a good technical question for you.
>
> From the newsgroups:
>
> "From: Gary Boswell ((E-Mail Removed))
> 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 Sheet. 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 ->
--

Jean-David Beyer wrote on 11/29/2004 13:02:
> But so what? How many sectors are on a track? That very clearly varies.
> If I try to read an entire drive; e.g., running badblocks in verbose
> mode on it, I can see that it slows down from around 57 Megabytes/second
> at the outside edge to about 31 Megabytes/second at the center. So
> clearly the number of sectors/track is not constant, but monotonically
> decreasing.

Of course it does. There is more space on the outer tracks...
This is called zone-bit recording:
http://www.pcguide.com/ref/hdd/geom/tracksZBR-c.html

-Joe

Dear user:
I am wondering why you need this!
On old IDE drives the CHS information was written on the disk... and was kae
anyway, but useful for BIOS setting.

For a long time (over 10 years) IDE/ATA has a query command to query the CHS
information: the host can request and get this info from the disk.

There even was a command to change it (YES!).

Today, the data is accessed by LBA (logical block address).
A logical block is still often 512 bytes of data, but in my opinion it
should be bumped to a higher number, like 2k (2048 bytes).

So you really do not need to know the number of CHS on your disk excepted
for curiosity.
----

(E-Mail Removed) wrote:
> Dear experts,
> I have a good technical question for you.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

(E-Mail Removed) wrote:
> Dear experts,
[snip]
> - for a given hard drive, how can I tell the size of the cylinder?

For the purposes of partition placement, fdisk will tell you the 'size of the
cylinder' of any installed hard drive

~ $ sudo /sbin/fdisk -l /dev/hda

Disk /dev/hda: 20.4 GB, 20490559488 bytes
255 heads, 63 sectors/track, 2491 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Or, you can examine the contents of /proc/ide/<drive_id>/geometry

~ $ cat /proc/ide/hda/geometry
physical 39703/16/63
logical 2491/255/63



- --
Lew Pitcher

Master Codewright & JOAT-in-training | GPG public key available on request
Registered Linux User #112576 (http://counter.li.org/)
Slackware - Because I know what I'm doing.
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