Re: [gentoo-user] sha1sum of cd

[Zac Medico]

Jorge Almeida wrote:

I've downloaded a KNOPPIX cd and burned it onto a cd via cdrecord (k3b having recently evolved to

brain death). The command was
    cdrecord  dev=/dev/hdc KNOPPIX_V3.9-2005-05-27-EN.iso
The sha1sum of the downloaded image is
51294cb7439a127efd36f819f636208163988972, which is what it's supposed to
be.
The cd boots, but something seems wrong ('ls /etc' hangs forever, and
segfaulted once).  So, maybe the burning was not right. I tried
    $ cat /dev/hdc|sha1sum
    cat: /dev/hdc: Input/output error
    8d792624cfe365a1b8ee1e9f06fe3520c28d91cc  -
Then,
    $ dd if=/dev/hdc of=knoppix.iso
    dd: reading `/dev/hdc': Input/output error
    1425088+0 records in
    1425088+0 records out

    $ sha1sum knoppix.iso
    8d792624cfe365a1b8ee1e9f06fe3520c28d91cc knoppix.iso
Last, I followed Zac Medico's suggestion in the "md5sum error" thread:
    $ readcd dev=/dev/hdc sectors=0-$(isoinfo -d -i /dev/cdrom | grep
    "Volume size is:" | grep -o "[0-9]*$")  f=- | sha1sum
    Read  speed:  7042 kB/s (CD  40x, DVD  5x).
    Write speed:  2818 kB/s (CD  16x, DVD  2x).
    Capacity: 356298 Blocks = 712596 kBytes = 695 MBytes = 729 prMB
    Sectorsize: 2048 Bytes
    Copy from SCSI (1,0,0) disk to file '-'
    end:    356296
    addr:   356296 cnt: 84
    Time total: 160.792sec
    Read 712592.00 kB at 4431.8 kB/sec.
    51294cb7439a127efd36f819f636208163988972  -

So, "there is order in this madness".

Can someone explain the meaning of this?


Jorge Almeida

Well, readcd works well for a cd while dd and cat do not. ;-)

The ls /etc hang and segaufault sounds like a unionfs problem (known bugs).  If 
you do dmesg|tail you will probabably see evidence of a unionfs error/oops.

I've been using a unionfs snapshot from 4/19 for the longest time because I 
have found later versions to be too unstable for my liking.

Zac
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