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My Mac OSX (10.8.4) had an external USB crash and it seems that ddrescue and dcfldd are the last hope, since none of the other utilities can mount the disc. After several days of researching, reading, and writing I have managed to produce ISO and DMG files from some test files on a DVD and a floppy, but they are unrecognized and fail to mount. Could someone please help me sort out my syntax problems from scratch?
From the commands you gave, the first one looks like an image of your external drive and the second one looks like you copied a file.
You plugged the external drive into a linux machine, correct? I'm wondering because you posted in a Linux forum but your mount commands response looks different. I don't know if Mac OSX or BSD even have a loopback device. What does it mean by "special"?
How was the external drive formatted? That determines the filesystem type to use. In Linux if it was a fat32 drive, as in a pen drive for example, then you would use -t vfat. However, this may be Linux specific.
On my "man mount" manpages, there are several "ufstype" options for UFS filesystems. If your mount options are similar, you should read your manpage to see if you need to use an option such as "44bsd". The problem is that there are several differences between different UFS implementations and some are undocumented. So you may need to provide further information in the "ufstype" option.
Thanks for the tip about "man mount." My terminal experience = about a week. (I am like a monkey with a hand-grenade.) I will go to the man pages and see what I can dig up.
qoute: You plugged the external drive into a linux machine, correct? I'm wondering because you posted in a Linux forum but your mount commands response looks different. I don't know if Mac OSX or BSD even have a loopback device. What does it mean by "special"?
If I find out what they mean by special we'll both know! (Maybe they mean, "It takes a special kind of idiot to screw up a machine like you did!" )
I am using both a USB floppy and ISO/DMG images located in my / directory for testing. If and when I learn how to do this properly, I will try the code on my failing EXT HD. Perhaps posting in a Linux (instead of Mac) forum complicates things a bit, but this was the only forum that I could find with such comprehensive dd help and how to's. http://linuxquestions.cachefly.net/i...ies/newbie.gif
Any advice is appreciated!
By a linux forum, I meant the forum on this site and not the LQ itself. There is a forum for BSD for example, and another one for non-Linux. No biggie. Since the moderator didn't relocate it, maybe there wasn't a best fit. Because the drive was external, I thought that you might have plugged it into a Linux machine.
A Special may mean the same thing as device. A device file is a special file. I haven't used BSD or OS-X so I don't know what a DMG file is. If it isn't a filesystem, then you can't mount it.
If a node is the same thing as a mount point, then your mount command is similar. Still, read through the mount man page. The filesytem types may be referred to differently.
I you are practicing mounting an image, you could still make an image of the usb drive. If you muck up the image file, you can always delete it and produce another. As long as you don't use the usb's device as the output.
I looked up DMG in Wikipedia. It is an image file, but may be compressed or encrypted. There are utilities for converting DMG files to ISOs if the DMG is an image of a CD or DVD, but it could contain other filesystems. Look at the instructions for using the command line tool "hdiutil".