[wellylug] DD no go

[Cliff Pratt]

David Antliff wrote:
> On Sun, Apr 6, 2008 at 10:41 AM, Cliff Pratt <enkidu at cliffp.com> wrote:
>>  I still think that you may be hitting a 4gb limit. What is in the input
>>  file?
>>
>>  Can you copy the input file into a formatted ext2/3 or FAT32 on that
>>  disk? I know that doesn't really help getting the data *out*, but it may
>>  show you have problems with the disk. Or it may be inconclusive.
> 
> If he's hitting a 4GB limit, why do these fail?
> 
> # dd if=/dev/zero of=/dev/sdb seek=8395975 count=5
> # dd if=/dev/zero of=/dev/sdb seek=8395978 count=100
>
Good point.
 >
> He's not copying any files. He's transferring data from one block
> device to another. There is no filesystem involved other than the one
> holding the /dev/ inodes.
> 
> I'd be interested to see what appears in 'dmesg' after running the
> first of those commands. /var/log/syslog might have something too.
> Could also turn on SMART for that disk (man hdparm) or even run the
> manufacturers diagnostics.
> 
> If the files were worth more than $100 to me, I'd have bought a second
> HDD by now and be done with it.
> 
What about the different geometries? I don't know how dd does it, but as 
I (believe) I understand it, the actually the physical tracks might vary 
in size though the number of blocks would be the same. Is it possible 
that dd tries to write tracks which are physically a bit longer than the 
physical track, or am I talking nonsense?

Going back to the original post the error was "Input/output error". You 
said "Secondly, that's normally what happens when you run out of space 
on the destination device, but after only 4.3GB?". I've not used 'dd' a 
lot but isn't the message usually "Disk Full" or something?

Cheers,

Cliff