Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
Solved

# easy question

Posted on 2001-06-08
Medium Priority
195 Views
how do you get a hard drives size using the sectors heads and cylinders
0
Question by:hilltop
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points

LVL 23

Expert Comment

ID: 6168913
I generally don't calculate it that way.  I go to the manuf web site and look up the model number.  You also get other pertinent info by doing that.
0

LVL 32

Accepted Solution

jhance earned 200 total points
ID: 6168957
SECTORS/TRACK x TRACKS/DISK x HEADS x BYTES/SECTOR = CAPACITY

Example:  63 sector/track, 16383 tracks, 16 heads, 512 bytes/sector

Capacity = 63 X 16383 X 16 X 512 = 8.4GB.
0

LVL 16

Expert Comment

ID: 6168975
http://www.pcguide.com/ref/hdd/geom/geomPhysical-c.html

That page may get you headed on the right track...or this information:
Figure 1.1 Detail of a Basic Disk with Four Partitions

The Ending Cylinder field in the partition table is 10 bits long, which limits the number of cylinders that can be described in the partition table to a range of 0?1,023. The Starting Head and Ending Head fields are each one byte long, which limits the field range to 0?255. The Starting Sector and Ending Sector fields are each six bits long, which limits the range of these fields to 0?63. However, the enumeration of sectors starts at 1 (not 0, as for other fields), so the maximum number of sectors per track is 63.

Because all hard disks are low-level formatted with a standard 512-byte sector, the maximum disk capacity described by the partition table is calculated as follows:

Maximum capacity = sector size x cylinders (10 bits) x heads (8 bits) x sectors per track (6 bits)

Using the maximum possible values yields:

512 x 1024 x 256 x 63 (or 512 x 2^24) = 8,455,716,864 bytes or 7.8 GB

See http://www.microsoft.com/technet/win2000/win2ksrv/reskit/sopch01.asp

-d
0

LVL 2

Expert Comment

ID: 6169082
You'll need the sector size as well.

Bytes in sector * sectors per track * # of cylinders  * # of heads should equal raw capacity of the hard drive.

Let's assume 512 byte sectors,
2100 cylinders
63 sectors per track
(this is from a Caviar AC31000)

512*2100*16*63 = 1,083,801,600 bytes

If you are trying to translate the number of bytes into MB or GB, remember that 1000 != 1024, and 1024 bytes = 1K.

This might look like 1.083 G, but remember 1000 bytes does not equal 1K.  So divide that number by 1024 several times and you wind up with 1.009G and you might feel you were cheated out of 74 MB.  Also remember that many manufacturers are inconsistent - sometimes they divide by 1000, sometimes by 1024, even in the same calculation.

A notorious example is calling a diskette with 1,457,664 bytes a 1.44MB floppy when it really only has 1.38 MB of space.  There are really 1.44 million bytes available on that disk, but not 1.44MB.  Microsoft actually got that one right.

With the floppy example, note that the real cpacity of the disk is 1,474,560. 33 sectors (16.5K) is used for overhead like FAT, boot sector, etc.  A similar circumstance will happen with a hard drive, so raw capacity does not equal usable capacity.

0

LVL 32

Expert Comment

ID: 6169150
melchioe,

You mean you came up with this all on your own?
0

LVL 16

Expert Comment

ID: 6169442
heh heh heh....
0

LVL 2

Author Comment

ID: 6169497
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In the modern office, employees tend to move around the workplace a lot more freely. Conferences, collaborative groups, flexible seating and working from home require a new level of mobility. Technology has not only changed the behavior and the expe…
This paper addresses the security of Sennheiser DECT Contact Center and Office (CC&O) headsets. It describes the DECT security chain comprised of “Pairing”, “Per Call Authentication” and “Encryption”, which are all part of the standard DECT protocol.
This is my first video review of Microsoft Bookings, I will be doing a part two with a bit more information, but wanted to get this out to you folks.
In this video, Percona Director of Solution Engineering Jon Tobin discusses the function and features of Percona Server for MongoDB. How Percona can help Percona can help you determine if Percona Server for MongoDB is the right solution for …
###### Suggested Courses
Course of the Month5 days, 20 hours left to enroll