/dev/sdb is the drive you're trying to "un-iso", it would appear that you've overwritten sdb's old MBR/GPT partition table.
gparted may not see any partitions and says it's all unallocated space (that's what mine does when I setup an .iso file as a loop device, and have gparted examine the loop device).
So, start up
gparted and examine
/dev/sdb, tell it to Create a new Partition Table (MBR/GPT/etc) by:
- Going to the menu Device -> Create Partition Table and
- write a new partition table.
The "msdos" type is the old MBR, or "gpt" is the new GPT partition table, use whichever you prefer or google for advice.
After that, make a new partition (or a few, whatever you want).
If you just want to make a bootable live USB, you can use a program like Unetbootin, or Universal USB Installer.
Or I prefer a multiboot USB (even if there's only one .iso to boot) since it doesn't overwrite the whole drive's partition table like plain
dd does, and you can use a filesystem like ext3/4 or something more reliable than FAT (FAT USB's tend to erase all their filenames somewhat regularly for me somehow, never a problem on the same USB with ext3).
Instructions can be found in this other A of mine and they're basically:
[As] described here on Arch's Wiki or here on
pendrivelinux.com, for many distros you just copy the ISO file
onto the usb and edit grub.cfg. Cliff notes instructions are:
- Mount the usb
- Install grub grub-install --force --no-floppy --boot-directory=/mnt/USB/boot /dev/sdx (replacing x with your actual USB device & /mnt/usb with mounted dir)
- Put demo grub.cfg ( http://pendrivelinux.com/downloads/multibootlinux/grub.cfg ) in
/mnt/USB/boot/grub and edit to match your iso's
Or see the Ubuntu help on creating & installing from bootable
USB's, can the Ubuntu tool Startup Disk Creator, Unetbootin, or
And I think you could even make it persistent by adding another partition on the USB just named "casper-rw", similar to these instructions on pendrivelinux.com , but I haven't tested it with a multiboot usb