ubuntu@ubuntu:~$ sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL
NAME FSTYPE SIZE MOUNTPOINT LABEL
sda 298.1G
├─sda1 ext4 290.2G
└─sda5 swap 7.9G [SWAP]
sdb iso9660 7.2G Ubuntu 14.04.1 LTS amd64
├─sdb1 iso9660 981M Ubuntu 14.04.1 LTS amd64
└─sdb2 vfat 2.3M
sr0 1024M
loop0 squashfs 938.7M /rofs
ubuntu@ubuntu:~$ sudo gparted
======================
libparted : 2.3
======================
(gpartedbin:6056): GLib-CRITICAL **: Source ID 7 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 6 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 10 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 9 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 29 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 28 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 33 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 32 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 38 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 37 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 43 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 42 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 46 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 45 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 51 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 50 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 54 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 53 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 57 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 56 was not found when attempting to remove it
Error informing the kernel about modifications to partition /dev/sda2 -- Device or resource busy. This means Linux won't know about any changes you made to /dev/sda2 until you reboot -- so you shouldn't mount it or use it in any way before rebooting.
(gpartedbin:6056): GLib-CRITICAL **: Source ID 138 was not found when attempting to remove it
(gpartedbin:6056): GLib-CRITICAL **: Source ID 137 was not found when attempting to remove it
/dev/sdb contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table?