[root@kvm ~]# parted /dev/sda mkpart extended 105G 1000G
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (Device or resource busy).  As a result, it may not reflect all of your changes until after reboot.
[root@kvm ~]# parted /dev/sda print free
Model: DELL PERC 6/i (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type      File system  Flags
        32.3kB  1049kB  1016kB            Free Space
 1      1049kB  525MB   524MB   primary   ext4         boot
 2      525MB   105GB   105GB   primary   ext4
 3      105GB   1000GB  894GB   extended               lba
        105GB   1000GB  894GB             Free Space

[root@kvm ~]# pvcreate /dev/sda3
  Device /dev/sda3 not found (or ignored by filtering).
[root@kvm ~]#