Talk:Checking the integrity of a Live CD

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(md5sum /dev/cdrom unreliable, now also in 7.0beta5 Manual)
 
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Any idea for reasonably simple test command immune to this?
Any idea for reasonably simple test command immune to this?
[[User:Hanzl|Hanzl]] 05:24, 24 September 2007 (EDT)
[[User:Hanzl|Hanzl]] 05:24, 24 September 2007 (EDT)
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Added some screen shots, discussion of the K3B verify bug and info on how to find the optical device name /dev/??? [[User:Marvin02|Marvin02]] 10:14, 15 March 2009 (EST)

Latest revision as of 15:14, 15 March 2009

The "md5sum /dev/cdrom" method, now also in the 7.0 beta 5 Manual (section 2.3), may be quite unreliable. Good discussion is here [1], citation:

If I had not specified -dao (session at once mode) and taken the cdrecord default recording mode (track at once), the following would have happened:
# md5sum /dev/cdrom
md5sum: /dev/cdrom: Input/output error
Further stubborn attempts at verification might produce something like:
# dd if=/dev/cdrom bs=2048 | md5sum
dd: reading `/dev/cdrom': Input/output error
269860+0 records in
269860+0 records out
...some bad sum here ...
And you would be convinced you had a coaster.

Users might get false errors for quite usable media, just due to garbage following the very end.

I think we should at least add something like "This test fails for CD recorded 'track at once'. Use 'session at once' mode (-dao switch when using cdrecord)."

Any idea for reasonably simple test command immune to this? Hanzl 05:24, 24 September 2007 (EDT)

Added some screen shots, discussion of the K3B verify bug and info on how to find the optical device name /dev/??? Marvin02 10:14, 15 March 2009 (EST)

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