How to copy burned CDs?

**A. Jorge Garcia** · 05-10-2005, 05:51 PM

I have a really fast burner at the office. I used to download ISOs there and burn KNOPPIX CDs all the time. Now my office has blocked a ton of sites so I can't download most ISOs anymore.

Can I burn one CD at home and make my own ISO at work? Can I use 'cat' or 'dd' for this?

For example, how about:

Code:

dd if=/dev/cdrom of=/dev/hda2/home/misterG/my.iso

Any other ideas out there?

TIA,
AJG[/code]

**OErjan** · 05-10-2005, 06:46 PM

yes iirc both those would work, or burn the iso on a CD or even better DVD.

**Dave_Bechtel** · 05-10-2005, 07:35 PM

--Your syntax is a bit off, but you have the general idea. I use ' cat ' for this; it's less resource-intensive than dd.

' time cat /dev/cdrom >/mnt/blah/dir/blah.iso '

Originally Posted by A. Jorge Garcia

I have a really fast burner at the office. I used to download ISOs there and burn KNOPPIX CDs all the time. Now my office has blocked a ton of sites so I can't download most ISOs anymore.

Can I burn one CD at home and make my own ISO at work? Can I use 'cat' or 'dd' for this?

For example, how about:

dd if=/dev/cdrom of=/dev/hda2/home/dad/my.iso

Any other ideas out there?

TIA,
AJG

**OErjan** · 05-10-2005, 08:27 PM

no the syntax is right for dd.

**Harry Kuhman** · 05-10-2005, 08:50 PM

Originally Posted by A. Jorge Garcia

I have a really fast burner at the office......

I have a really fast burner at home.

But I always burn my CDs at 4x. I've found that at higher speeds things are just not as reliable. One would certainly expect a burn on a drive by a good name drive manufacturer who advertises speeds like 52x to actually work, but the sad truth is they don't. There is an awful lot of error recovery information in a typical CD (so much so that you can store 800 megs of data on a 700 meg CD if you write in mode 2 and bypass the error recovery information!), and this error recovery often hides the problems of writing at high speeds, but there are real and serious problems.

I didn't want to believe this myself. But I became a convert when I burned several SVCD videos in mode 2. There were just way to many noticable and serious video problems. And I found that the problems "went away" if I burned the CDs at a 4x. Further, we have seen a lot of booting problem with Knoppix that have been determined to be the result of burning the CD too fast. Why? I dodn't know! One would expect the drive's error correction to kick in (the Knoppix disk is burnt with error correction data, not in mode 2), but either it doesn't or the errors are so extreme that there are too many to be corrected. Whatever ther reason, the fix is simple: burn at a slow speed. Here are just a couple of threads where high speed burn problems have been confirmed, but there are many more: http://www.knoppix.net/forum/viewtopic.php?t=17788 and
http://www.knoppix.net/forum/viewtop...?p=78925#78925 .

I burn a lot of CDs. But I've learned the hard way that the ones I burnt at high speed are just not reliable. And I expect they will be even less reliable as they age. My advice is to burn at a slow speed. Yea, this is bad news if you want to crank out hundreds of CDs (but many pressing services will accept orders for as few as 100 and give you a better quality CD), but for one or two it only makes sense to burn slowly. And this also says a lot about what to expect if you buy a burnt CD from someone cranking them out to sell on e-bay; do you think they are taking the time to burn them slowly to get the best results for the user, or quickly so they can make money in the shortest amount of time?

**A. Jorge Garcia** · 05-10-2005, 08:52 PM

Wow, thanx for all the input on this question already!

OK, so:

Code:

dd if=/dev/cdrom of=/dev/hda2/home/misterG/my.iso

or

Code:

cat /dev/cdrom > /mnt/hda2/home/misterG/my.iso

should both work, but cat is quicker?

Also, would I get an exact copy of the original ISO that I can check with the original md5sum?

BTW, Dave, I remember when you taught me about cat many moons ago.... Thank you!

Oh, and Harry, I don't ever burn at the max speed. At home I burn at 8x and at work I burn at 32x. The home burner is a 16x and the work one is much faster than 32x (sorry I forget exactly what the exact speed is at the moment).

TIA,
AJG

PS: I burn a lot of CDs for my students and for ebay and I always burn slow and test my CDs before distributing them to anyone.

**Dave_Bechtel** · 05-11-2005, 05:44 AM

--No, it's not.

--Look at it closely:

of=/dev/hda2/home/misterG/my.iso

--If he types that in verbatim, it will give him an error - " dd: opening `/dev/blah/blah': No such file or directory " -- because /dev/hda2/home... does not exist.

--Devices don't have subdirectories, filesystems do.

Originally Posted by OErjan

no the syntax is right for dd.

**Dave_Bechtel** · 05-11-2005, 05:49 AM

--Slightly OT, but when a loaner audio CD from the library ** EXPLODED ** in a hand-me-down 52X burner, I junked it. I refuse to buy anything 52x - or even 48x - anymore. 32x is as high as I'm willing to go. Even went out of my way to find a "slower" DVD burner; and my cdrecord sessions are limited to 24x.

--No problems so far. But good media definitely helps (Taiyo Yuden highly recommended.)

Originally Posted by Harry Kuhman

Originally Posted by A. Jorge Garcia

I have a really fast burner at the office......

I have a really fast burner at home.

But I always burn my CDs at 4x. I've found that at higher speeds things are just not as reliable. One would certainly expect a burn on a drive by a good name drive manufacturer who advertises speeds like 52x to actually work, but the sad truth is they don't. There is an awful lot of error recovery information in a typical CD (so much so that you can store 800 megs of data on a 700 meg CD if you write in mode 2 and bypass the error recovery information!), and this error recovery often hides the problems of writing at high speeds, but there are real and serious problems.

I didn't want to believe this myself. But I became a convert when I burned several SVCD videos in mode 2. There were just way to many noticable and serious video problems. And I found that the problems "went away" if I burned the CDs at a 4x. Further, we have seen a lot of booting problem with Knoppix that have been determined to be the result of burning the CD too fast. Why? I dodn't know! One would expect the drive's error correction to kick in (the Knoppix disk is burnt with error correction data, not in mode 2), but either it doesn't or the errors are so extreme that there are too many to be corrected. Whatever ther reason, the fix is simple: burn at a slow speed. Here are just a couple of threads where high speed burn problems have been confirmed, but there are many more: http://www.knoppix.net/forum/viewtopic.php?t=17788 and
http://www.knoppix.net/forum/viewtop...?p=78925#78925 .

I burn a lot of CDs. But I've learned the hard way that the ones I burnt at high speed are just not reliable. And I expect they will be even less reliable as they age. My advice is to burn at a slow speed. Yea, this is bad news if you want to crank out hundreds of CDs (but many pressing services will accept orders for as few as 100 and give you a better quality CD), but for one or two it only makes sense to burn slowly. And this also says a lot about what to expect if you buy a burnt CD from someone cranking them out to sell on e-bay; do you think they are taking the time to burn them slowly to get the best results for the user, or quickly so they can make money in the shortest amount of time?

**Dave_Bechtel** · 05-11-2005, 05:52 AM

--IIRC, yes the md5sum should match (at least after cat, which is my own experience.)

Note: Jorge, I corrected your dd syntax in the quote below.

Originally Posted by A. Jorge Garcia

Wow, thanx for all the input on this question already!

OK, so:

Code:

dd if=/dev/cdrom of=/mnt/hda2/home/misterG/my.iso bs=1M

or

Code:

cat /dev/cdrom > /mnt/hda2/home/misterG/my.iso

should both work, but cat is quicker?

Also, would I get an exact copy of the original ISO that I can check with the original md5sum?

BTW, Dave, I remember when you taught me about cat many moons ago.... Thank you!

Oh, and Harry, I don't ever burn at the max speed. At home I burn at 8x and at work I burn at 32x. The home burner is a 16x and the work one is much faster than 32x (sorry I forget exactly what the exact speed is at the moment).

TIA,
AJG

PS: I burn a lot of CDs for my students and for ebay and I always burn slow and test my CDs before distributing them to anyone.