permission denied to dd disk?

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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

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Answer 1

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Camelot

Level 9

54,333 points

Dec 22, 2006 4:27 PM in response to waipeinan

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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Answer 2

waipeinan Author

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25 points

Dec 22, 2006 4:49 PM in response to Camelot

wow superfast response.
i am really not a terminal user so please be patient.
This drive is half of a raid, so i assumed i needed to copy the complete drive to be able to recreate the raid after?

will the code you suggest work in this instance?

this raid contains so much photographic work i am suitably cautious...
thanks

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Answer 3

waipeinan Author

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Dec 22, 2006 4:51 PM in response to waipeinan

also the destination disk is now identified as disk0s3 and the source is disk3s4

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Answer 4

waipeinan Author

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Dec 22, 2006 5:49 PM in response to waipeinan

so i am now running tak
sudo dd if=/dev/disk3s4 of=/dev/disk0s3

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Answer 5

waipeinan Author

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Dec 22, 2006 6:17 PM in response to waipeinan

and i get the response
bell:~ bell$ sudo dd if=/dev/disk3s4 of=/dev/disk0s3
Password:
dd: /dev/disk0s3: Resource busy

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Answer 6

Camelot

Level 9

54,333 points

Dec 22, 2006 10:44 PM in response to waipeinan

Are you sure you want disk0?

disk0 would typically be the internal/startup disk.

What does diskutil list tell you?

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Answer 7

waipeinan Author

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Dec 23, 2006 1:10 AM in response to Camelot

disk0 is just where i have slotted the new ata drive, in place of the dvd, as i was having problems with the original code i thought it may have something to do wiht the ata/sata adapter

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Answer 8

Dec 24, 2006 3:31 PM in response to waipeinan

If the disk, you want to copy the data to is not a raid volume, you have to use the rdisk instead of the disk device, so a:
sudo dd if=/dev/disk3s4 of=/dev/rdisk0s3
should be succesful, if rdisk0s3 really is the correct place you want to copy the data.
Also, if you dont want the copy take an an endless time, use a larger block size then the default of 512, like bs=1048576

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Answer 9

waipeinan Author

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Dec 26, 2006 9:39 AM in response to nobody loopback

thankyou loopback, ill try that when i return from the break, but what is the full code including the block size specification. or will it ask for this to be specified?

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Answer 10

Dec 26, 2006 11:02 AM in response to waipeinan

sudo dd if=/dev/disk3s4 of=/dev/rdisk0s3 bs=1048576

see "man dd" in the terminal.

The man page of dd lists other helpful options, "conv=noerror,sync" ist good, if your source is partially unreadable, but you like to copy it anyway.

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Answer 11

maciscool

Level 3

586 points

Dec 26, 2006 12:56 PM in response to waipeinan

dd doesn't usually work for me on mac, I usually use ditto.
ditto <source_disk> <destination_disk>
For more on how to use ditto type man ditto, or ask here. There is also a nice front end to ditto called Carbon Copy Cloner

iBook G4 14" 1.42 GHz 60GB 768MB - Blueberry Clamshell 300MHz 20GB 320MB- both-> Mac OS X (10.4.8) Preforma 630CD, LCIII, Compaq laptop 266MHz 5GB 192MB (GNU/Linux, NOT windoze)

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Answer 12

Dec 26, 2006 2:16 PM in response to maciscool

depending on the problem, dd or ditto might be the better alternative.

dd makes a 100% clone of a disk/partition
ditto only copies the files (and fscks up big when dealing with special files and permissions)
If someone just wants to rescue his data ditto or rsync is fine.
dd cannot copy a filesystem to a location with different size but ditto will.
If you need to backup a disk for the purpose of restore later to the original location and want an identical result (example: think of some music software copy protection) dd is the better alternative.
Also dd will copy a damaged disk/filesystem ditto will fail here too

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Answer 13

waipeinan Author

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Dec 27, 2006 11:46 AM in response to nobody loopback

i believe in this instance it's dd i require as the volume im trying to duplicate is only half of an 800 gb raid, therefor it will not mount and cannot be copied by apps like carbon copy cloner.
im looking forward to trying the last code supplied by loopback when i return to london this evening and if it works i hope to be able to access amost 800gbs of photographic work trapped by a failed drive in/out card.

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Answer 14

waipeinan Author

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25 points

Dec 28, 2006 10:12 AM in response to waipeinan

well i tried and the same result

localhost:~ bell$ dd if=/dev/disk4s4 of=/dev/rdisk0s3 bs=1048576
dd: /dev/disk4s4: Permission denied
localhost:~ bell$

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Answer 15

waipeinan Author

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Dec 28, 2006 10:23 AM in response to waipeinan

whoops, forgot the sudo, it now appears to be running as i can hear the drives winding up. How can i check the progress?

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