In this brief article I will explain how to add a new physical parition to an existing disk, and then to use that new parition to create a mountable logical volume.
Let’s assume that we have a 1TB disk, and we are running CentOS/RedHat, in this case I am using version 6.5
First attempt to view partition table, turns out that disk has GUID Partition table:
# fdisk -l /dev/sda WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 999.7 GB, 999653638144 bytes 255 heads, 63 sectors/track, 121534 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x6929f946 Device Boot Start End Blocks Id System /dev/sda1 1 121535 976224255+ ee GPT
Let’s try to view partition table using GNU parted, and then add a 189GB partition.
The command ‘print free’ shows the free space at the end.
I used the command ‘mkpart’ to add the partition. Notice that partition 3 stops at 211GB.
So I can create a new partition from 211GB onwards. The end of free space is 1000GB, so I picked 400GB as my end, leaving another 600GB free for later use.
I called my new partition ‘bigdisk’ and it’s numbered 4.
# parted /dev/sda
GNU Parted 2.1
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print free
Model: Dell Virtual Disk (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
17.4kB 1049kB 1031kB Free Space
1 1049kB 211MB 210MB fat16 boot
2 211MB 840MB 629MB ext4
3 840MB 211GB 210GB lvm
211GB 1000GB 789GB Free Space
(parted) mkpart
Partition name? []? bigdisk
File system type? [ext2]? ext4
Start? 211GB
End? 400GB
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.
(parted) print
Model: Dell Virtual Disk (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 1049kB 211MB 210MB fat16 boot
2 211MB 840MB 629MB ext4
3 840MB 211GB 210GB lvm
4 211GB 400GB 189GB bigdisk
I have decided to remove the 189GB partition and increase it’s size. So instead of starting at 211GB and ending at 400GB, I am ending at 600GB.
This gives me a 389GB partition.
# parted GNU Parted 2.1 Using /dev/sda Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) print Model: Dell Virtual Disk (scsi) Disk /dev/sda: 1000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 211MB 210MB fat16 boot 2 211MB 840MB 629MB ext4 3 840MB 211GB 210GB lvm 4 211GB 400GB 189GB bigdisk (parted) rm 4 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. (parted) mkpart Partition name? []? bigdisk File system type? [ext2]? ext4 Start? 211GB End? 600GB 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. (parted) print Model: Dell Virtual Disk (scsi) Disk /dev/sda: 1000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 211MB 210MB fat16 boot 2 211MB 840MB 629MB ext4 3 840MB 211GB 210GB lvm 4 211GB 600GB 389GB bigdisk (parted) quit Information: You may need to update /etc/fstab.
I will now view my LVS physical extent:
# pvs PV VG Fmt Attr PSize PFree /dev/sda3 vg_hv1 lvm2 a-- 195.31g 11.71g
I need to add the 389GB partition as a physical extent. I know it’s /dev/sda4 because when I ran parted it showed partition #4.
# pvcreate /dev/sda4 dev_is_mpath: failed to get device for 8:4 Physical volume "/dev/sda4" successfully created # pvs PV VG Fmt Attr PSize PFree /dev/sda3 vg_hv1 lvm2 a-- 195.31g 11.71g /dev/sda4 lvm2 a-- 362.70g 362.70g
I have one volume group on my system:
# vgs VG #PV #LV #SN Attr VSize VFree vg_hv1 1 7 0 wz--n- 195.31g 11.71g
I am going to add another volume group, I don’t have to do this. I can simply extend my existing volume group, but I want to make another volume group in order to logically separate my applications.
# vgcreate vg_ic /dev/sda4 Volume group "vg_ic" successfully created # vgs VG #PV #LV #SN Attr VSize VFree vg_hv1 1 7 0 wz--n- 195.31g 11.71g vg_ic 1 0 0 wz--n- 362.70g 362.70g
Now I can create my logical volumes as needed. My existing logical volumes are:
# lvs LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert lv_home vg_hv1 -wi-ao---- 19.53g lv_root vg_hv1 -wi-ao---- 39.06g lv_swap vg_hv1 -wi-ao---- 7.81g lv_tmp vg_hv1 -wi-ao---- 9.77g lv_var vg_hv1 -wi-ao---- 9.77g lv_vm1 vg_hv1 -wi-ao---- 48.83g lv_vm2 vg_hv1 -wi-ao---- 48.83g
Adding additional logical volumes:
# lvcreate -L 80G vg_ic -n lv_cdrive Logical volume "lv_cdrive" created # lvs LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert lv_home vg_hv1 -wi-ao---- 19.53g lv_root vg_hv1 -wi-ao---- 39.06g lv_swap vg_hv1 -wi-ao---- 7.81g lv_tmp vg_hv1 -wi-ao---- 9.77g lv_var vg_hv1 -wi-ao---- 9.77g lv_vm1 vg_hv1 -wi-ao---- 48.83g lv_vm2 vg_hv1 -wi-ao---- 48.83g lv_cdrive vg_ic -wi-a----- 80.00g
That’s about it! Next step can be to use ‘mkfs.ext4 /dev/mapper/vg_ic-lv_cdrive’ if you want to install ext4 on the LVM, followed by mounting it in /etc/fstab.
Or you can use it with KVM to install a VM on. If you like to add disk in another way, do share your experience.
Syed Ali 
Fantastic.. I was looking rigorously for partitioning GPT disk and creating logical partitions out from free space through parted tool. Found none until i stuck here.
Thanks a lot Syed Ali..!