I have installed bootable ubuntu on hard disks but now I can not format them with Disk Utility program. When I try to format it says "One or more partitions are busy on /dev/sdb" for both hard disks. Is there any way to format these drives?
EDIT: With "Disk Utility" program when I select one of the hard drives It shows 3 volumes;
99 MB FAT 111 GB EXT4 9 GB UNKNOWN
I can not format this unknown volume.
With Gparted program, It doesn't shows Unknown volume only shows 111GB EXT4.