Linux Tutorials - Herong's Tutorial Examples - v5.45, by Herong Yang
Create New PV (Physical Volume)
Describes what is a PV (Physical Volume) - a single physical hard disk, or a partition of a hard disk, to be managed by the LVM (Logical Volume Manager). A tutorial example is given on how to create a new PV.
What Is PV (Physical Volume)? PV represents a single physical hard disk, or a partition of a hard disk, to be managed by the LVM (Logical Volume Manager). One or more PVs are combined to form a single VG (Volume Group).
There are a number commands provided on CentOS 8 systems for you to create and manage PVs.
1. List all PVs that are currently created on all connected physical storage media using the "pvs" command, which is also a sub-command of the "lvm" command. The output shows that I have 1 PV created on /dev/sda7, linked to "cl" VG with 0 free space.
herong$ sudo pvs PV VG Fmt Attr PSize PFree /dev/sda7 cl lvm2 a-- 96.65g 0 herong$ sudo lvm pvs PV VG Fmt Attr PSize PFree /dev/sda7 cl lvm2 a-- 96.65g 0
2. Display details of each PV using the "pvdisplay" command, which is also a sub-command of the "lvm" command. The output shows the PV is configured with 4MiB for each PE (Physical Extent).
herong$ sudo pvdisplay --- Physical volume --- PV Name /dev/sda7 VG Name cl PV Size <96.66 GiB / not usable 3.00 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 24743 Free PE 0 Allocated PE 24743 PV UUID bFdGY0-JZK8-5OdS-qV3B-A7qQ-...
What Is PE (Physical Extent)? PE represents a unit of continuous storage space in a PV to be mapped to a LV (Logical Volume).
How To Create a New PV? If you have some free space on a hard disk, you can create a partition, and convert it into a PV using the "pvcreate" command as shown below.
1. Verify free space on the hard disk. The output shows a 900GB free space between partition #1 snd #2.
herong$ sudo parted /dev/sdb print free Number Start End Size File system Name Flags 17.4kB 1049kB 1031kB Free Space 1 1049kB 100GB 100GB ext4 primary 100GB 1000GB 900GB Free Space 2 1000GB 2000GB 1000GB primary 2000GB 2000GB 1122kB Free Space
2. Create a new partition of 100GB as a primary partition and set it to use "ext4" file system. The output shows that the new partition is created as /dev/sdb3.
herong$ sudo parted /dev/sdb mkpart primary ext4 100GB 200GB Information: You may need to update /etc/fstab. herong$ sudo parted /dev/sdb print free Number Start End Size File system Name Flags 17.4kB 1049kB 1031kB Free Space 1 1049kB 100GB 100GB ext4 primary 100GB 100GB 595kB Free Space 3 100GB 200GB 100GB primary 200GB 1000GB 800GB Free Space 2 1000GB 2000GB 1000GB primary 2000GB 2000GB 1122kB Free Space
3. Create a new PV with /dev/sdb3 using the "pvcreate" command, which is also a sub-command of the "lvm" command.
herong$ sudo pvcreate /dev/sdb3 Physical volume "/dev/sdb3" successfully created. herong$ sudo pvdisplay "/dev/sdb3" is a new physical volume of "93.13 GiB" --- NEW Physical volume --- PV Name /dev/sdb3 VG Name PV Size 93.13 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID G0DaHC-tLo2-c7Du-DDDo-7y6A-...
Note that if you are converting an partition that has been formatted with a file system, you get a warning message saying that the file system type signature will be wiped out. Of course its data will be damaged. So only do this if you don't need the data any more.
herong# pvcreate /dev/sdc2 WARNING: ext4 signature detected on /dev/sdc2 at offset 1080. Wipe it? [y/n]: y Wiping ext4 signature on /dev/sdb2. Physical volume "/dev/sdb2" successfully created.
Note that you can also convert an entire new hard disk into a PV by using the hard disk device file like /dev/sdc.
See next tutorials on what is VG (Volume Group) and how to build VG with PVs.
Table of Contents
Cockpit - Web Portal for Administrator
What Is LVM (Logical Volume Manager)
►Create New PV (Physical Volume)
Add/Remove PV on VG on the Fly
Extend /home LV with a New Partition
SELinux - Security-Enhanced Linux
SSH Protocol and ssh/scp Commands
Software Package Manager on CentOS - DNF and YUM
vsftpd - Very Secure FTP Daemon