Messages in this thread | | | Date | Thu, 27 Dec 2001 17:33:24 -0500 | From | Douglas Gilbert <> | Subject | Re: dd cdrom error |
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Leung Yau Wai <chris@gist.q-station.net> wrote: > I come across a problem which seem exist in kernel > 2.4.x but not in 2.2.x. > > The problem is that, when I try to using dd to create > a ISO image of a cdrom then around dumping the end of > the disc it will give out the following error message: > > e.g. dd if=/dev/cdrom of=n.iso
If dd is used like that, it is surprising you do not get more errors. An iso9660 image does not necessarily fill the track. So the IDE equivalent of the SCSI READ CAPACITY command will often report a size that includes unwritten sectors at the end. Those unwritten sectors can/will cause IO errors when an attempt is made to read them.
A very useful program called "isosize" has made a return to util-linux-2.10s (and later). Execute: isosize -x /dev/cdrom to find the number of sectors and the sector size of the iso9660 fs held _within_ the first track. Then use those numbers as the "count=" and "bs=" arguments to dd respectively.
If you still have problems try turning DMA off via hdparm or set the DMA mode back to 33 MHz (-X34).
Doug Gilbert - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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