Re: dvd writes truncated 3 Mbytes

[Bill Davidsen <davidsen@tmr.com>]

Gene Heskett wrote:

> Greetings;
>
> I've just tried to burn a dvd iso 4 times, 2 different brands of disks,
> getting an identical but bad md5sum for all 4 writes.
>
> K3B reports it has written 1160 of 1163 Mbytes each time, but doesn't
> seem to have a problem with that.
>
> Kernel is 2.6.14.2, without packet writing for cd/dvd turned on, but I
> have one with it enabled building now.  K3B is 0.11.13, cdrecord is
> 2.1(dvd), groisofs is 5.21, mkisofs is 2.1-a34.  The drive is a Lite-On
> DVDRW SOHW-1673S.
>
> I just ran growisofs from the cli, and it also gets exactly the same
> bad md5sum, not reporting the final write.  Here is the cli line & end
> of burn session reports:
> ----------------
> [root@coyote FC4]# growisofs -dvd-compat -Z /dev/cdrom=CAELinuxBeta1.iso
> [...] 
> 1188462592/1219631104 (97.4%) @3.9x, remaining 0:05
> 1207107584/1219631104 (99.0%) @3.9x, remaining 0:02
> builtin_dd: 595536*2KB out @ average 3.9x1385KBps
> /dev/cdrom: flushing cache
> /dev/cdrom: writing lead-out
> ----------------
> [root@coyote FC4]# md5sum </dev/cdrom
> 292969c8f81e7c0e3ed0ee76a5a637ad  -
>
> This last is the same bad md5sum I've seen 4 times before.
>
> Has anyone else encountered a similar problem?  I've been making
> good cd's all along with no problems, in this new drive, till now.
>
> I've supposedly subscribed to this list, but in 30 minutes, no
> confirmation message has appeared.
>
>  
You are using an unreliable method to do the check, an I'm not surprised 
it doesn't work. Do this instead:
 dd if=/dev/cdrom bs=2k count=595536 | md5sum -

Joerg has explained this in some detail, as have several of us, you must 
read back what you write, no more no less, then the check will be 
meaningful.

--
bill davidsen <davidsen@tmr.com>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979