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How to backup my CD-ROM Movie Collection

Posted on 2003-03-20
Medium Priority
Last Modified: 2011-09-20
I just bought a new DVDROM-RW writer.  I'm trying to backup my CD-ROM collection but the backup software I'm using is saying that there not enough room on my 4.7 GB DVD blank disks. Do I need to compress the movies before backing them up or what? Is there any good software that simplifies this process?
Question by:Gmoney

Expert Comment

ID: 8178350
I think you put your data/movies more than the dvd capacity. I don't recommend you compressing the movies though, when you need it you'll have to uncompress it (takes time and hdd space).

Just try removing some data/movies so it fits your dvd.
Or you'll just buy a new dvd? :)

Accepted Solution

Yo-NuTZ earned 500 total points
ID: 8179915
Well let's clarify things a little bit: A DVD does not have 4.7GB (4700 MB) it has 4.7Gb(4700 Mb) that means 4388 MB. With other words your movie collection has to be no bigger than 4388 MB (right-click on the folder -> Properties) because it won't fit in. I know it's a big scam, i've discovered it recently too. As a reccomandation for a software to burn your DVD's i would say NERO, it's the best in my oppinion and you can see very easy and well in it your collection size. One more thing you should know DVD's don't support Muti-Session, so you write it once, even only 1 MB and you can add no more, the only write method they know is Disc-At-Once. Good luck.

Expert Comment

ID: 8182641
Actually, it's not a scam - it has to do with the way that your computer thinks about numbers.  Since PC's are forced to think in binary mode, and all of their data addressing is set in that mode, you can't give a PC a decimal addressing scheme.  IOW, you can't give a PC 1000 addresses, you have to give it 1024, because 1000 isn't a power of 2, but 1024 is.  Just like a kilobyte is 1024 bytes, and a Mb is 1024 kilobytes(or 1024^2 bytes), a GB is 1024 Mb ( or 1024 ^3 bytes).  So when a DVD (or a harddisk for that matter) is rated at a certain capacity in GB, you can multiply that by 1024^3 to get the actual number of bytes the drive has in total storage.

Now here's the kicker:
Unfortunately, you can't have all that space.  You lose it because of the way PC's address physical storage space.  First you lose a goodly chunk to the File Allocation Table (under FAT and FAT32) or to the MFT (under NTFS).

second, you lose space because your PC does address indivudual bytes of storage.  It addresses storage space in sectors and  clusters, which have a set size (which depends on which OS you have, the size of the partitions on the storage media and some other factors.)  If a file is more than that set size, it spans across the clusters, filling them up one at a time, until it's all written on the disk.  However, since files are rarely exactly x number of clusters in length, and no more than one file can use a cluster at one time, you end up with some empty space at the end of that last cluster.  This is called slack space, and can make a difference in how much you can actually store on a disk.  If you have Windows 2000 you can even see this difference for yourself:

Right click on a file (not a shortcut or folder) and choose properties

Compare the lines that say Size:  and Size on disk:

I did this just now on a URL file and got the following results

Size:  134 bytes
Size on disk:  4.00kb (4096 bytes)

So I lost 3964 bytes that I simply cannot use.  Now I have something like 2,000 or so favorites on my PC - this translates into about 7.5 Mb of lost space.

While I doubt this rambling dissertation is actually going to answer your question, hopefully it does explain why you can't put 4700 MB of data on a DVD.


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