How to determine the size of cylinder? - Redhat

This is a discussion on How to determine the size of cylinder? - Redhat ; 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 = ...

Thread: How to determine the size of cylinder?

1. How to determine the size of cylinder?

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
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

2. Re: How to determine the size of cylinder?

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2

wrote in message
| 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
| 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

3. Re: How to determine the size of cylinder?

linuxquestion@yahoo.com wrote:

> 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
> 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

4. Re: How to determine the size of cylinder?

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:

> linuxquestion@yahoo.com wrote:
>
>> 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
>> 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.

5. Re: How to determine the size of cylinder?

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

6. Re: How to determine the size of cylinder?

linuxquestion@yahoo.com wrote in

> 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
> 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 ->
--

7. Re: How to determine the size of cylinder?

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

8. Re: How to determine the size of cylinder?

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.
----

linuxquestion@yahoo.com wrote:
> Dear experts,
> I have a good technical question for you.

9. Re: How to determine the size of cylinder?

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

linuxquestion@yahoo.com 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//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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10. Re: How to determine the size of cylinder?

linuxquestion@yahoo.com writes:
> My question is:
> - for a given hard drive, how can I tell the size of the cylinder?

I hope you realize that for most modern hard drive this question is
meaningless. That is if you really want to know what you're asking.

Since the hard drive changes the size of the cylinders to pack more
data in the outer cylinders. You could try to ask what is the size of
a given cylinder? But it would not serve much, because modern hard
drives remap bad sectors on other cylinder "transparently", and use
really only LBA, even if the CHS addressing is still supported for
legacy.

--
__Pascal Bourguignon__ http://www.informatimago.com/
The world will now reboot; don't bother saving your artefacts.

11. Re: How to determine the size of cylinder?

Lew Pitcher wrote in

> [snip]
>> - for a given hard drive, how can I tell the size of the cylinder?

[snip]
> Or, you can examine the contents of /proc/ide//geometry
>
> ~ \$ cat /proc/ide/hda/geometry
> physical 39703/16/63

This is bogus, of course, and has nothing to do with the physical number
of cylinders, heads, or or sectors on the disk. Only the vendor's data
sheet will give you the physical information.

--
- Mark ->
--

12. Re: How to determine the size of cylinder?

AnonymousFC3 wrote in
news:HdWdnRv8m7bQQDbcRVn-vQ@comcast.com:

> 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.

But it will not relate to the physical parameters of a modern disk.

--
- Mark ->
--