Using parted to create a new partition table

Using parted to create a new partition table 

[root@ractw21 ~]# parted
GNU Parted 3.1
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) select /dev/sdb                                                  
Using /dev/sdb
(parted) print                                                            
Error: /dev/sdb: unrecognised disk label
Model: ATA VBOX HARDDISK (scsi)                                           
Disk /dev/sdb: 21.5GB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 
(parted) mklabel msdos
(parted) print                                                            
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sdb: 21.5GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start  End  Size  Type  File system  Flags

(parted) mkpart                                                           
Partition type?  primary/extended? primary
File system type?  [ext2]? ext4                                           
Start? 1                                                                                                                                     
End? -1                                                                   
(parted) print                                                            
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sdb: 21.5GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 
Number  Start   End     Size    Type     File system  Flags
 1      1049kB  21.5GB  21.5GB  primary

Create an ext4 Filesystem and mount the partition a first time 
[root@ractw21 ~]#  mkfs.ext4 /dev/sdb1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5242368 blocks
262118 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2153775104
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
    4096000
Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

[root@ractw21 ~]# mkdir /backup
[root@ractw21 ~]# mount /dev/sdb1 /backup
[root@ractw21 ~]# df /dev/sdb1      
Filesystem     1K-blocks  Used Available Use% Mounted on
/dev/sdb1       20509264 45080  19399328   1% /backup