CD Space puzzle

  • Thread starter Thread starter Dan Drewry
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Dan Drewry

I decided to do some backing up to a CD. The printing on the CD says it
has 700 MB (12X). I used My Computer to drag files onto it. After
putting 418 MB of files on it, I right-clicked it and checked
Properties. It says the capacity is 333 MB, and there are 157 MB used.
What's going on here? Is the "12X" the key, and what does it mean?
 
Dan Drewry said:
I decided to do some backing up to a CD. The printing on the CD says it has
700 MB (12X). I used My Computer to drag files onto it. After putting 418
MB of files on it, I right-clicked it and checked Properties. It says the
capacity is 333 MB, and there are 157 MB used.
What's going on here? Is the "12X" the key, and what does it mean?
Click to expand...
That means it writes 12 times as fast as the original CD. They wrote very
slowly...
Jim
 
X is for speed recognization. 1x = 150Kbps. That means your CD can handle
1800 Killo Byte Per Second when data is read or written by your CD-Writer.
Your writer will try to auto adjust the writing speed according to your CD.
E.g. if you have writer with 52x32x52x specifications that means it can write
at 52x, re-write at 32x speed and read at 52x speed. If you have 12x Blank CD
then your write and cd writing software will try to auto adjust the speed to
maximum supportted by your blank media.

To check the appropriate disk size and usage, you should try features of
your CD Writing Program. E.g. if you are using Nero 6 then there is a tool
called Nero Info Tool or in Nero Express there is a button under More called
Disc Info. Which will give you the exact information about the disc size and
usage.

Hope this help, let us know!
 
OK - I guess the 12X only refers to speed and not capacity.

But now I'm really confused. First of all, I didn't use a CD writing
program - I dragged the files onto the CD using My Computer. But I used
Nero Disk Info as you suggested, and it shows file sizes adding up to
426 MB, it says there are 117 MB available, but the total capacity is
423 MB!
These numbers just don't add up and make no sense to me.
 
File Slack. The files on your hard disk will be larger than on CD. And
everyone measures things differently.

Also CDs actually hold less than what they advertise. That's at the bottom
here.

File Slack, again.

In data storage, the smallest amount of disk space that can be allocated to
hold a file is called a cluster. Most files are not the same size as the
cluster size on a hard disk. The difference between the actual file size
and the cluster size is called file slack. File slack is wasted space.
There will always be wasted space no matter what size the clusters are.
File size plus file slack equals Size on disk.

If your hard drive has 4KB cluster size and you have a file that is 1KB,
File Properties will show:

Size: 1.00KB (1,024 bytes)
Size on Disk: 4.00KB (4,096 bytes)

Size is the actual size of file's (or folder's) data.

Size on disk is the actual space that the file (or folder) takes up on the
hard drive.

What File Properties does not show is the file slack. From the example
above, the file slack would be 3KB (2,048 bytes) of wasted space.

KB (kilobyte) is a binary number, 2 to the tenth power, 2^10
or 1,024 bytes. So 1KB is 1,024 bytes, not 1000 bytes like we would
normally think of using decimal numbers

For best overall file system performance, a 4KB cluster size is best.

If the cluster size is too large, there is more file slack.

If the cluster size is too small, there will be more fragmentation.

The smaller the cluster size, the more efficiently a disk stores information
because unused space within a cluster cannot be used by other files.

You can find the cluster size, also called allocation unit, by looking at
the chkdsk log in the Event Viewer.

Open the Event Viewer...
Start | Run | Type: eventvwr | Click OK |
Look in Application | Listed as Information |
Event ID: 1001
Source: Winlogon

Similar to this:
4096 bytes in each allocation unit.

How to locate and correct disk space problems on NTFS volumes in Windows XP

http://support.microsoft.com/kb/315688

Disk Quota Charges Increase If You Turn On the NTFS Compression
Functionality
http://support.microsoft.com/kb/320686

Binary vs. Decimal Measurements
http://www.pcguide.com/intro/fun/bindec.htm

----------

How much data can they hold? 650MB? 680MB?
http://www.cdrfaq.org/faq07.html#S7-6

CD-R Media List - Sorted by CD-R Capacity
http://www.cdmediaworld.com/hardware/cdrom/cd_cdr_info_fs.shtml

CD Media World - CD-RW Recordable Media Info Table
Click on...
CD-RW Info Table - Sorted by Total Space
http://www.cdmediaworld.com/hardware/cdrom/cd_cdrw_info.shtml

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In
 
Assume that every blank CD has the capacity of 700MB / 80 Mins. Insert a
Blank CD click the Disc Info. Note down the Total Capacity and Available
Space. Both should be the same.

Now, insert a Data CD and again run the Disc Info. See the Available
Capacity and Total Capaicty. If the Available Capacity is disable that means
you can not write any further on the remaining space of the CD. That is why
the Written Data size is the Total Capacity of the CD.

Moreover, check the Disc Info, if you have a MultiSession Data CD. It will
show you like:

Total Capacity 0:21.49 4MB
Available Capacity 77:04.25 677MB

That means, CD has already a data of 4MB and it has remaining writable space
of 677MB. Total both of them is 681MB. According to me the remaining 19MB is
consumed for Multi Sessions to seprate the data.

Check the Disc Info of a Video CD and notice the Capacity. The size in MB
may be upto 850MB. This is because Video CD and Audio CDs are compare through
Time not by the size.

Further, there are types of CDs, which you can notice in Disc Info. For a
Data CD it will show you "CD-ROM", for a Video CD it will show you "CD-ROM
XA".

So maybe you will never get an accurate result for a used CD. If you have a
MultiSession CD with 50MB of data on it that means you have 650MB or 630MB
space available to re-write.

Hope this help, let us know!
 
I have been overwhelmed with information in these two replies! Very good
explanations from you and Wesley - thank you!
 
Dan, I always just think of a two by four, then I don't have to think about
the rest of it. ;-)

Nominal: 2" X 4" Actual: 1-1/2" X 3-1/2"

Of course, when a board is first rough sawn from a log, it is a true 2" X
4", but the drying process and planing of the board reduce it to the
finished 1-1/2" X 3-1/2" size.

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In
 
Wesley said:
Dan, I always just think of a two by four, then I don't have to think
about the rest of it. ;-)

Nominal: 2" X 4" Actual: 1-1/2" X 3-1/2"

Of course, when a board is first rough sawn from a log, it is a true
2" X 4", but the drying process and planing of the board reduce it to
the finished 1-1/2" X 3-1/2" size.
Click to expand...


Since 2x4s (along with the other lumber sizes) are smaller than they used to
be, I have to believe that, along with drying and planing, there is a fair
amount of dishonesty at work.

Reminds me of hard drives and gigabytes.
 
Since 2x4s (along with the other lumber sizes) are smaller than they used
to be, I have to believe that, along with drying and planing, there is a
fair amount of dishonesty at work.
Click to expand...

You may be correct on that one.
Reminds me of hard drives and gigabytes.
Click to expand...

LOL

--
Hope this helps. Let us know.

Wes
MS-MVP Windows Shell/User

In
 
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