You will only see more than a "c" partition under two circumstances:
- There is a disklabel on the drive, with partitions defined, or
- There is an MBR on the drive, with partitions recognized as mountable.
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I'm not looking over your shoulder as you type commands, so this is only from what you tell me. The "Invalid argument" error with that dd command should
only occur when one of these three things is true:
- You mistype the device node argument, such as using the letter O instead of the number 0
- The device is not attached to the kernel at the time you issue the command
- Your /dev directory has been damaged, and does not have an rsd0c node in the directory.
Try the following:
# fdisk sd0
This should show if the drive has a partition table in its MBR, and if it shows anything at all, it is reading sector #0. Before running it, please start an xconsole, so in the event there are any kernel messages, you see them as they happen. (An xconsole is a window that shows kernel messages. Please review the xconsole(1) man page.)