How to copy burned CDs?

[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/misterG/my.iso

Any other ideas out there?

TIA,
AJG[/code]

[OErjan]

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

[Dave_Bechtel]

--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 '


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]

no the syntax is right for dd.

[Harry Kuhman]

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/viewtopic.php?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]

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

OK, so:


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

or


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]

--No, it's not. :shock:

--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. :roll:


no the syntax is right for dd.

[Dave_Bechtel]

--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.)



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/viewtopic.php?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]

--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. ;-)


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

OK, so:


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

or


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.

[A. Jorge Garcia]

Dave, I figured you were referring to the "/mnt...."

BTW, what is bs=1M?

Thanx,
AJG

[OErjan]

oops, i never spotted that, would have if i typed it but...
bs=1M means that the blocksize is 1Mb or 1024k...
which is slightly faster than the default 512b

[Dave_Bechtel]

BlockSize = 1 Meg; see ' man dd '. It speeds things up a bit if you use a higher blocksize than the default.


Dave, I figured you were referring to the "/mnt...."

BTW, what is bs=1M?

Thanx,
AJG

[A. Jorge Garcia]

OK, I just tried this proceedure


cat /dev/cdrom /mnt/hda3/iso/my.iso
using a newly knoppix-installer'ed PC (hd install of 3.8.1)

and I get these errors:


/dev/cdrom no such device or address
/mnt/hda3/iso/my.iso no such file or directory
Do I have to mount the cdrom first? Is /dev/cdrom not the device that KNOPPIX 3.8.1 defines? I tried /dev/scd0 too as thats used during a liveCD bootup, still no joy.

Do I have to mount hda3 first? I'm already running KNOPPIX from hda3....

TIA,
AJG

[Dave_Bechtel]

:roll: Read the directions a little more closely... You forgot the ' > '

--BTW, trying scd0 was a good shot; I don't know why it didn't work. Try:

' cat /dev/sr0 > /mnt/hda3/iso/my.iso '

--If you can mount a CD from KDE, switch to a console window and ' df ' - that will tell you what device it's using.


OK, I just tried this proceedure


cat /dev/cdrom /mnt/hda3/iso/my.iso
using a newly knoppix-installer'ed PC (hd install of 3.8.1)

and I get these errors:


/dev/cdrom no such device or address
/mnt/hda3/iso/my.iso no such file or directory
Do I have to mount the cdrom first? Is /dev/cdrom not the device that KNOPPIX 3.8.1 defines? I tried /dev/scd0 too as thats used during a liveCD bootup, still no joy.

Do I have to mount hda3 first? I'm already running KNOPPIX from hda3....

TIA,
AJG

[OErjan]

try incerting a little > in there.

cat /dev/cdrom>/mnt/hda3/iso/my.iso

and yes the hdd must be mounted.
hmm, can you mount a CD? if so try mounting a cd and
do a mount|grep cdrom this should give you the proper device.
so should cat /etc/fstab|grep cdrom.
dmesg|grep CD might help aswell.
heh, there are several waqys of finding what your CDrom is called.
and it should work. if not try the dd comand...

[A. Jorge Garcia]

OK, that's weird. I thought I used the >, maybe I didn't, sorry.... OOPS, let me try that again.


paul@Colossus:~$ cat /etc/fstab|grep cdrom
/dev/cdrom /mnt/cdrom iso9660 defaults,ro,user,noexec,noauto 0 0
paul@Colossus:~$ dmesg|grep CD
hdc: SONY CD-RW CRX140E, ATAPI CD/DVD-ROM drive
Vendor: SONY Model: CD-RW CRX140E Rev: 1.0n
Type: CD-ROM ANSI SCSI revision: 02
BTW, mount|grep cdrom returned nothing as the cdrom was not mounted.

What's also strange is that my KNOPPIX system in hd installed to hda3. So, when it boots, isn't hda3 already mounted?

You, know, I never understood why all the partitions show up on the desktop when booting the liveCD and they don't when booting from a hd install.

Regards,
AJG

[A. Jorge Garcia]

...stranger and stranger

Well, I tried just this at home on a hd installed KNOPPIX 3.7 box. As a test case I burned a miniCDR (210MB) of BCCD 2.2.1 (200MB). Then I ran


cat /dev/scd0 > /mnt/hda2/home/iso/BCCD/test5.iso
and

dd if=/dev/scd0 of=/mnt/hda2/home/iso/BCCD/test4.iso bs=1M

and both worked - sort of.

Now the problem is that both runs produced isos 113.8MB in size, though dd was a bit faster, that obviously do not match the original md5sum!

What gives?

TIA,
AJG