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Level 1

25 points

permission denied to dd disk?

i have been trying to dd a slice of a raid to a brand new drive and keep getting
bell:~ bell$ sudo dd if=/dev/disk4 > /dev/disk3
-bash: /dev/disk3: Permission denied
errors.
I have run some little test to this disk that have worked but any dd to this drive fails (haveing tried to clone an ipod as a test), when i paste the code it denies befor i even hit return.
I am really no terminal user and have been following instructions from a helpful techi friend online, but even he is stumpped!
any clues

the slice is half of an 800gb raid which is not mounted as one of the controler boards on one of the drives has failed, it is connected on a sonnet tempo 4x4 card as is the new drive, which is also on an ata-sata adapter. Its all a bit messy but im trying to save the raid in the first place and make tidy in the next.

g5 dual 2.3, Mac OS X (10.4.8)

Posted on Dec 22, 2006 4:18 PM

Best reply

Camelot

Level 9

54,339 points

Posted on Dec 22, 2006 4:27 PM

If you want to dd a slice of a RAID, you need to specify the slice. As written you're trying to dd an entire disk, not just a slice. In addition, you do not want to redirect the output of the dd command, rather you should use the of parameter

You should be doing something more like:

<pre class=command>sudo dd if=/dev/disk4s2 of=/dev/disk3s2</pre>

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33 replies

waipeinan Author

Level 1

25 points

Dec 29, 2006 2:36 PM in response to waipeinan

absolute genius!
the raid is now complete again and i have access to over 600gb of irreplaceable photgraphic data....
this could have cost 000's of euro's via a data recover company!

thank you loopback. Magic!

Dec 29, 2006 3:22 PM in response to waipeinan

Congratulations !

And good to know that this works for my job (IT is my job) that OSX does not write any magic about the kind of disks of a raid to both disks.

btw.: better use a raid-1 or at least a raid 5 for important data.
A raid-0 is fine, if you need fast scratch space for work, but not for data storage.

waipeinan Author

Level 1

25 points

Dec 29, 2006 5:01 PM in response to nobody loopback

yes indeed. I was torn between wanting faster disk access for large file size photoshop images 500 + mb and having all the work in one place. Back up was and now is the next stage, and obviously an important one. Someone once said "if a file isn't in two places then it does not exist" was perhaps quite right!.
But it's always money too.....

thanks again

permission denied to dd disk?