dd and IO

[Bill Cunningham]

I seem to be having a bit of a problem I don't understand. I've never
tried this before with CD/DVDs. I have a CD/RW that windows says is CDFS.
Linux doesn't quite identify it. Ok I want to clea or zreo this out with dd.
I can use a burner utility and erase this. With dd I get data no longer
async. Something about page (memory?) and sectors written and read.

I don't know all the conv= and ibs= or obs= alters. But tried this.

dd if=/dev/zero of=/dev/sr1 and I tried,

dd if=/dev/zero of=/dev/sr1 bs=1024 count=2

Both give me these errors. It is a USB DVD/RW. I am also trying this and
getting errors.

dd if=/dev/sr1 of=/xpmce.iso

I want to write an ISO 9660 XP MCE OS CD/R into a ISO. And get data errors.
What's going on?

Bill

[Bill Cunningham]

"Bill Cunningham" <billcun...@suddenlink.net> wrote in message
news:neomud$qc2$1...@dont-email.me...

Oh and I'm using Fedora 20 if that means anything.

[John Reiser]

> I have a CD/RW that windows says is CDFS.
> Linux doesn't quite identify it. Ok I want to clea or zreo this out with dd.
> I can use a burner utility and erase this. With dd I get data no longer
> async. Something about page (memory?) and sectors written and read.

Post here a transcript (copy+paste) that shows each command
that you gave, and the exact response you received.

[Joe Beanfish]

CDs/DVDs are odd beasties. In the old days cdrecord was the way to deal
with them. Looks like Fedora is moving to libburn??

[Bill Cunningham]

"Joe Beanfish" <joebe...@nospam.duh> wrote in message
news:neqt38$615$2...@dont-email.me...

> CDs/DVDs are odd beasties. In the old days cdrecord was the way to deal
> with them. Looks like Fedora is moving to libburn??

I think I'm moving to gentoo or archlinux. Fedora puts out a new OS
seemingly once a year.

Bill

[Joe Pfeiffer]

You can't write to a CD/DVD with dd. You have to use burning software
that understands the media.

[Bill Cunningham]

"Joe Pfeiffer" <pfei...@cs.nmsu.edu> wrote in message
news:1b37qmv...@pfeifferfamily.net...

> You can't write to a CD/DVD with dd. You have to use burning software
> that understands the media.

With dd I am trying to read from a CD/R and write an ISO. That might be
the problem. The CD/R isn't an ISO 9660. So it's not going to copy to a file
I am creating called xpmce1.iso is it. Ihave XP MCE on 3 CD/Rs. They are
pretty old. One is damaged. IDK if I can get it copied with ddrescue or
dd_rescue or not.

Bill

[Jorgen Grahn]

On Sat, 2016-04-16, Bill Cunningham wrote:
>
> "Joe Pfeiffer" <pfei...@cs.nmsu.edu> wrote in message
> news:1b37qmv...@pfeifferfamily.net...
>
>> You can't write to a CD/DVD with dd. You have to use burning software
>> that understands the media.
>
> With dd I am trying to read from a CD/R and write an ISO.

That wasn't very obvious in your first postings; I interpreted it the
way JP did, too.

> That might be the problem. The CD/R isn't an ISO 9660.

Doesn't almost every CD-ROM use that file system? What does it use
instead, and how do you know?

> So it's not going to copy to a file I am creating called xpmce1.iso
> is it.

Of course it is! dd doesn't care how you name your files. And it
doesn't care what file system it is -- it just copies blocks of data.

/Jorgen

--
// Jorgen Grahn <grahn@ Oo o. . .
\X/ snipabacken.se> O o .

[Bill Cunningham]

"Jorgen Grahn" <grahn...@snipabacken.se> wrote in message
news:slrnnh4otc.5...@frailea.sa.invalid...

> On Sat, 2016-04-16, Bill Cunningham wrote:
>>
>> "Joe Pfeiffer" <pfei...@cs.nmsu.edu> wrote in message
>> news:1b37qmv...@pfeifferfamily.net...
>>
>>> You can't write to a CD/DVD with dd. You have to use burning software
>>> that understands the media.
>>
>> With dd I am trying to read from a CD/R and write an ISO.
>
> That wasn't very obvious in your first postings; I interpreted it the
> way JP did, too.

Sorry. I have tried several things. In addition to the /dev/zero device.

>> That might be the problem. The CD/R isn't an ISO 9660.
>
> Doesn't almost every CD-ROM use that file system? What does it use
> instead, and how do you know?

XP says it's CDFS. I think that's an older format.

>> So it's not going to copy to a file I am creating called xpmce1.iso
>> is it.
>
> Of course it is! dd doesn't care how you name your files. And it
> doesn't care what file system it is -- it just copies blocks of data.

That's what I thought. I have read to that it wants to cache.
iflag=nocache I have tried and oflag=direct that doesn't work.

Bill

[Jorgen Grahn]

On Sat, 2016-04-16, Jorgen Grahn wrote:
> On Sat, 2016-04-16, Bill Cunningham wrote:
>>
>> "Joe Pfeiffer" <pfei...@cs.nmsu.edu> wrote in message
>> news:1b37qmv...@pfeifferfamily.net...
>>
>>> You can't write to a CD/DVD with dd. You have to use burning software
>>> that understands the media.
>>
>> With dd I am trying to read from a CD/R and write an ISO.
>
> That wasn't very obvious in your first postings; I interpreted it the
> way JP did, too.

Going back, what actually happened was you asked one question (about
zeroing a CD-RW), then changed the subject and asked another. JP
replied to the first one. It now seems you're more interested in this
second one:

I am also trying this and getting errors.

dd if=/dev/sr1 of=/xpmce.iso

I want to write an ISO 9660 XP MCE OS CD/R into a ISO. And get
data errors. What's going on?

Well, that should work if you are root (so you can create files in /)
and the CD isn't broken. If it's broken you should

- get an error message from dd
- /xpmce.iso will not be complete
- and probably you'll find complaints from the kernel in /var/log/.

[Bill Cunningham]

"Jorgen Grahn" <grahn...@snipabacken.se> wrote in message

news:slrnnh4svo.5...@frailea.sa.invalid...

> Going back, what actually happened was you asked one question (about
> zeroing a CD-RW), then changed the subject and asked another. JP
> replied to the first one. It now seems you're more interested in this
> second one:
>
> I am also trying this and getting errors.
>
> dd if=/dev/sr1 of=/xpmce.iso
>
> I want to write an ISO 9660 XP MCE OS CD/R into a ISO. And get
> data errors. What's going on?
>
> Well, that should work if you are root (so you can create files in /)
> and the CD isn't broken. If it's broken you should
>
> - get an error message from dd
> - /xpmce.iso will not be complete
> - and probably you'll find complaints from the kernel in /var/log/.

Well it didn't. I always believed dd was raw data, binary. I booted into XP
and erased the CD with CD/DVD erase/burn tools and it's ready to be written
to again. So the CD isn't broke. I will try with another CD tomorrow. will
save and post the errors.

Bill

[Bill Cunningham]

"Bill Cunningham" <billcun...@suddenlink.net> wrote in message

news:neud6b$f0$1...@dont-email.me...

Wait a minute scratch that. I am all confused today. That was another CD
a CD-RW. Ok with the CD/R of course it's mounting in linux and I can go in
and read that data. One of these CDs I know is defective. But not this one.
I have tried 2 CD/Rs actually and got the same results. I'll get back
tomorrow.

Bill

[Bill Cunningham]

OK well. I don't know what to say. I used this and it worked,

dd if=/dev/sr1 of=/xpmce1.iso iflag=nocache oflag=direct

The copy was made of 650 MB or so. Not so much as a hiccup. Well one of
these CDRs is damaged. I will have to try ddrescue with it. Thanks for the
help. I hope I haven't bothered anyone too much. Maybe those flags helped or
not.

Bill

[Jorgen Grahn]

On Sat, 2016-04-16, Bill Cunningham wrote:

> OK well. I don't know what to say. I used this and it worked,
>
> dd if=/dev/sr1 of=/xpmce1.iso iflag=nocache oflag=direct

I suspect that just "dd if=/dev/sr1 of=/xpmce1.iso" would have
worked, too.

> The copy was made of 650 MB or so. Not so much as a hiccup. Well one of
> these CDRs is damaged. I will have to try ddrescue with it. Thanks for the
> help. I hope I haven't bothered anyone too much.

You haven't, but you are often hard to follow. (Communication is
difficult, so that's not surprising.)

> Maybe those flags helped or not.

I think not, but yes.

[Bill Cunningham]

"Jorgen Grahn" <grahn...@snipabacken.se> wrote in message

news:slrnnh5tf1.5...@frailea.sa.invalid...

> On Sat, 2016-04-16, Bill Cunningham wrote:
>> OK well. I don't know what to say. I used this and it worked,
>>
>> dd if=/dev/sr1 of=/xpmce1.iso iflag=nocache oflag=direct
>
> I suspect that just "dd if=/dev/sr1 of=/xpmce1.iso" would have
> worked, too.
>
>> The copy was made of 650 MB or so. Not so much as a hiccup. Well one of
>> these CDRs is damaged. I will have to try ddrescue with it. Thanks for
>> the
>> help. I hope I haven't bothered anyone too much.
>
> You haven't, but you are often hard to follow. (Communication is
> difficult, so that's not surprising.)
>
>> Maybe those flags helped or not.
>
> I think not, but yes.

OK no error has stopped copying but this is what I have gathered from one
created IO.

blk_update... critical medium error sector 1244192
IO_error sector 1244240
IO_error logical block 311060 async page read

1244240 in
1244240 out
637 MB

Will dd not stop if there's an error and just keep copying? I think what I
did before is plugin my USB DVD/RW and try to use it too fast. When I wait
for recognition (you know serial, slow, especially USB) errors are printed.
I use dd and there's no problem. Basically before I jumped in too fast and
got those errors.

But copying is not breaking. Should I run ddrescue over these ISO 9660s?

Bill

[Jorgen Grahn]

On Sun, 2016-04-17, Bill Cunningham wrote:
>
> "Jorgen Grahn" <grahn...@snipabacken.se> wrote in message
> news:slrnnh5tf1.5...@frailea.sa.invalid...
>> On Sat, 2016-04-16, Bill Cunningham wrote:
>>> OK well. I don't know what to say. I used this and it worked,
>>>
>>> dd if=/dev/sr1 of=/xpmce1.iso iflag=nocache oflag=direct
>>
>> I suspect that just "dd if=/dev/sr1 of=/xpmce1.iso" would have
>> worked, too.
>>
>>> The copy was made of 650 MB or so. Not so much as a hiccup. Well one of
>>> these CDRs is damaged. I will have to try ddrescue with it. Thanks for
>>> the
>>> help. I hope I haven't bothered anyone too much.
>>
>> You haven't, but you are often hard to follow. (Communication is
>> difficult, so that's not surprising.)
>>
>>> Maybe those flags helped or not.
>>
>> I think not, but yes.
>
> OK no error has stopped copying but this is what I have gathered from one
> created IO.
>
> blk_update... critical medium error sector 1244192
> IO_error sector 1244240
> IO_error logical block 311060 async page read

That does not seem good.

> 1244240 in
> 1244240 out
> 637 MB
>
> Will dd not stop if there's an error and just keep copying?

My guess was that it will not, but I can be wrong.

Looking at the manual, it doesn't say anything explicitly. However
there is a 'noerror' option to "continue after read errors" so I
suppose if you don't enable it, it should stop at the first read
error.

> I think what I did before is plugin my USB DVD/RW and try to use it
> too fast. When I wait for recognition (you know serial, slow,
> especially USB) errors are printed. I use dd and there's no
> problem. Basically before I jumped in too fast and got those errors.

Hm ... you shouldn't get errors just by plugging in the device.

> But copying is not breaking. Should I run ddrescue over these ISO 9660s?

No idea; I haven't used it. Sorry.