dd freezes system

I don’t know if this is a hardware issue or not, but it’s a hell of a bug. At first I thought this was a K3B problem, because that’s how I usually extract iso files, but I found out recently it’s probably not K3B.

When trying to extract an iso file from existing CD or DVD discs using dd, the process seems to start, and then I get a total system freeze. Mouse cursor stops moving, keyboard seems unresponsive. Ctl-Alt-Bckspce does nothing, Ctrl-Alt-F1 does nothing. I have to use the power button on the box to forcibly kill the machine. The resulting iso image (what there is of it), comes out to 1.5 MB every time. It doesn’t matter if it’s a video or data DVD or CD. Making an iso using mkisofs works perfectly. I’d love to figure out why dd doesn’t work, so I can go back to using K3B for these tasks.

I’ve only been running Linux for about a year, so I’m still unskilled at troubleshooting. I did not have this problem until I upgraded to 11.0 from 10.3.

Looking for help, any offered will be appreciated. Thanks.

–chriscrutch

Maybe your CDROM reader is dodgy and has problem reading disks and the machine spends all its time retrying? Watch /var/log/messages with tail -f while you are reading the CD to check this theory.

Good thought. That’s not it. The last message before freezing is “mounted for uid 1000” for something of that nature, and it happens after it gets auto-mounted. After I launch dd, there are no messages before the freeze.

Just for grins, I connected an external USB burner that I also used to use with 10.3. Doing the same dd operation using the external USB drive results in just an error (“input/output error”), not a total system freeze. Guess that means it has something to do with my hardware, after all, at least partially.

–chriscrutch

Just bumping the thread, hoping someone has some ideas. This is a problem I’d really like to get resolved.

–chriscrutch

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Have you tried just seeing if it’s a combination of reading and writing?
~ For example:

dd if=/dev/cdrom >/dev/null

Good luck.

chriscrutch wrote:
| Just bumping the thread, hoping someone has some ideas. This is a
| problem I’d really like to get resolved.
|
| --chriscrutch
|
|
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Good thought. Unfortunately, that produces the same result: big crash. Thank you for the reply.

–chriscrutch

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Have you tried another drive? Another computer? I don’t recall ever
seeing this happen so I’d start by ruling out the hardware.

Good luck.

chriscrutch wrote:
| Good thought. Unfortunately, that produces the same result: big crash.
| Thank you for the reply.
|
| --chriscrutch
|
|
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> This is a problem I’d really like to get resolved.

you are probably not gonna like this THREE step solution, but i offer it
anyway:

  1. add 10.3 to your machine [multi-boot] and use it when 11.0 lets you
    down…

  2. file a bug report on the dd problem with 11.0 (or it might never get
    fixed)

  3. continue watching here because maybe someone comes along with the/an
    answer that is helpful enough that you can delete your 10.3 partition…


DenverD (Linux Counter 282315)
A Texan in Denmark

chriscrutch wrote:

>
> Good thought. Unfortunately, that produces the same result: big crash.
> Thank you for the reply.
>
> --chriscrutch
>
>

Some things to try, maybe we can narrow it down some more.

You say that

dd if=/dev/cdrom > /dev/null

crashes the system. This implies something with the cdrom drive itself,
cabling between drive and motherboard, or motherboard (several things, but
that’s later)

My apologies, but your thread was ‘moved’ and while I do remember reading
the initial posts, they’re somewhere else… so if I ask a question that’s
already been answered, I’m sorry.

What speed drive is the cdrom?
Does this crash occur with ANY CD in the drive? or just THIS particular CD
in the drive?
In what manner does the computer crash?
Is it a hard lock?
Spontaneous reboot?
Spontaneous poweroff?
Garbage on screen, then one of above?

Does the following affect your system:

dd if=/dev/zero of=/dev/null bs=512 count=2M

It copies 1 Gig of data from /dev/zero to /dev/null. no cdrom involved.
It’ll likely take up to 2 minutes to finish, depending on speed of your
machine, but it’s a good indicator.

If THAT crashes your machine, I’d say you have a heat issue based on cpu
load, check the ‘goop’ (yes, I know it’s really called Thermal Paste,
preferably with suspended colloidal silver particles… nyeah!)… check
the ‘goop’ between your cpu and heatsink. clean and replace as necessary.

Oh yeah, a thought… make sure the little fan on the motherboard which
cools the ‘northbridge’ chipset is running properly. Mine died a few
months ago and I got really weird data errors all of a sudden. It handles
ALL the I/O data between the various busses, and it can get quite warm
quickly. (and could conceivably contribute to this problem…)

Is it a DVD-rom drive (or DVD writer… does it handle DVD’s?)… if so, do
you have a 40conductor cable on it, or an 80conductor? The higher data
transfer rates of a DVD drive really need the 80conductor cable to keep
crosstalk down. Spurious interrupts and data requests can confuse the
system.

I’ve sort of given a grocery list of things to check and try… hope it’s
not overwhelming. Rather have you try several things and come back than do
it one at a time (sooo slooowww!).

Your mission Mr. Phelps… (this computer will self-destruct in 30
seconds…) (yeah yeah, not funny)

Loni


L R Nix
lornix@lornix.com

What speed drive is the cdrom?

It’s an 18x DVD-+RW dual-layer.

Does this crash occur with ANY CD in the drive? or just THIS particular CD
in the drive?

I haven’t found a disc yet that doesn’t produce the same result. DVDs (data or video, encrypted or not) or CDs (data or audio). Even blank discs.

In what manner does the computer crash?
Is it a hard lock?
Spontaneous reboot?
Spontaneous poweroff?
Garbage on screen, then one of above?

It’s a hard lock. There’s some spin-up on the drive, then the drive stops and everything freezes. Keyboard and mouse become unresponsive. Ctl-Alt-F1 and Ctl-Alt-Bkspc do nothing. The only resort it to physically press the power button to power off the system.

Does the following affect your system:

dd if=/dev/zero of=/dev/null bs=512 count=2M

It copies 1 Gig of data from /dev/zero to /dev/null. no cdrom involved.
It’ll likely take up to 2 minutes to finish, depending on speed of your
machine, but it’s a good indicator.

No problem there at all. It also only took about a second rather than two minutes, but no error message. Output ends with: 1073741824 bytes (1.1 GB) copied, 0.960072 s, 1.1 GB/s.

Oh yeah, a thought… make sure the little fan on the motherboard which
cools the ‘northbridge’ chipset is running properly. Mine died a few
months ago and I got really weird data errors all of a sudden. It handles
ALL the I/O data between the various busses, and it can get quite warm
quickly. (and could conceivably contribute to this problem…)

I certainly hope that isn’t it. This is a brand-new box from Gateway only a couple months old now, but I’ll check it.

Is it a DVD-rom drive (or DVD writer… does it handle DVD’s?)… if so, do
you have a 40conductor cable on it, or an 80conductor? The higher data
transfer rates of a DVD drive really need the 80conductor cable to keep
crosstalk down. Spurious interrupts and data requests can confuse the
system.

I’ll have to open the system to check, but again, it’s a brand-new Gateway, not a home build, so I’m assuming they did it right.

Thanks for things to check on, Loni and ab. DenverD, you’re right: that’s not exactly an ideal proposition, but if I’ve gotta do it…

–chriscrutch

As another test, I plugged in a USB stick and used dd to copy that. It worked just fine.

–chriscrutch

chriscrutch wrote:

>
> As another test, I plugged in a USB stick and used dd to copy that. It
> worked just fine.
>
> --chriscrutch
>
>

Well Pooh!! That pretty much removes the motherboard from suspicion.

Bad DVD drive?

You’re going to laugh at me, but I’d suggest removing the drive, turning it
over and around and everything to confuse it, maybe take it outside and let
it see the sunlight for a moment or two… talk sternly to it, gently check
its cable connections and jumpers… and then reinstall it.

You might show it the latest flyer from your favorite computer store,
casually remarking how inexpensive the new DVD drives are getting…

Yeah, laugh… I’ve worked with computers and electronics long enough to
almost sorta kinda believe in karma and gremlins. And the simple fact that
a calm removal and reinstallation can sometimes fix things that a furious
debugging session cannot.

(also might disconnect a spurious ground loop, remove oxidation from
contacts or connectors…)

You can stop laughing now…

Loni

(I once spent three hours troubleshooting a new motherboard, case and
powersupply… and when I finally threw up my hands and sat down for a cup
of tea, I noticed that the new powersupply was set for 220v, instead of
110v. Guess what I check FIRST now?)


L R Nix
lornix@lornix.com

Recently my DVD burner seemed to not be able to handle DVD-R although it could handle DVD+R fine. That seemed to go away after a reboot.(But I don’t trust it anymore for archiving, so I do those burns on a newer machine now.) This is probably no help to you since you probably have rebooted several times since. But it highlights the fact that some of us take Linux uptimes for granted that we forget that some electronics do get themselves confused internally (and a DVD drive does have onboard microcontroller, etc) and a reset sometimes helps. So Lornix’s suggestion isn’t so silly after all. It could really be contacts.

Once upon a time, there were reports that Linux killed floppy drives. Eventually it turned out that Linux machines were rebooted so rarely (compared to other OSes) that the floppy drives accumulated dirt in the bearings due to the lack of the bootup seek burst of “exercise”. Somebody wrote a program to make the drive do a seek to be run periodically and that solved the problem. I’m not kidding.