Create LVMs using parted
Logical Volume Groups
A Logical Volume Group (LVM) is a way to aggregate multiple physical disks into a single, contiguous space, which can then be divided into logical volumes. This abstraction allows for more flexible disk management by enabling dynamic resizing of file systems, making it easier to expand or contract the available space as needed.
To learn more about LVMs and how to install it, see LVMs.
Creating LVMs using parted
In this section, we'll go through the process of creating Logical Volume Managers (LVMs) using parted. The steps are similar to those covered earlier, but it's helpful to see the complete process in one place.
Lab Setup
We'll be working with /dev/xvdb, which has a total of 10GB of memory and currently only has two partitions created on it.
Create partitions
Using parted, we'll create another partition on it:
[root@tst-rhel ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 50G 0 disk
├─xvda1 202:1 0 1M 0 part
└─xvda2 202:2 0 50G 0 part /
xvdb 202:16 0 10G 0 disk
├─xvdb1 202:17 0 953M 0 part
└─xvdb2 202:18 0 954M 0 part [SWAP]
xvdc 202:32 0 9G 0 disk
[root@tst-rhel ~]# parted /dev/xvdb
GNU Parted 3.2
Using /dev/xvdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted)
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
Create the 3rd partition for LVM. Notice that we use tab completion to see all available file system types, there is none for LVM. We just press enter and let Linux set which is default for LVM.
(parted)
(parted) mkpart
Partition name? []? lvm1
File system type? [ext2]?
affs0 affs6 amufs3 btrfs hfs linux-swap(new) reiserfs
affs1 affs7 amufs4 ext2 hfs+ linux-swap(old) sun-ufs
affs2 amufs amufs5 ext3 hfsx linux-swap(v0) swsusp
affs3 amufs0 apfs1 ext4 hp-ufs linux-swap(v1) xfs
affs4 amufs1 apfs2 fat16 jfs nilfs2
affs5 amufs2 asfs fat32 linux-swap ntfs
File system type? [ext2]?
Start? 3G
End? 4GB
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
3 3000MB 4000MB 1000MB ext2 lvm1
After setting partition 3 to LVM, you will notice that the flag for partition 3 also changes to LVM.
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
3 3000MB 4000MB 1000MB ext2 lvm1
(parted) set 3 lvm on
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
3 3000MB 4000MB 1000MB ext2 lvm1 lvm
Create another LVM (Optional)
Following the same steps as before, we create a 4th partition and set it to LVM. This time, we use GiB instead of GB to specify the start and end sectors, ensuring the correct sizing.
[root@tst-rhel ~]# parted /dev/xvdb
GNU Parted 3.2
Using /dev/xvdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
3 3000MB 4000MB 1000MB lvm1 lvm
(parted) mkpart
Partition name? []? lvm2
File system type? [ext2]?
Start? 4GiB
End? 5GiB
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
3 3000MB 4000MB 1000MB lvm1 lvm
4 4295MB 5369MB 1074MB ext2 lvm2
(parted) set 4 lvm on
(parted) print
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1000MB 2000MB 999MB one
2 2000MB 3000MB 1000MB linux-swap(v1) swap swap
3 3000MB 4000MB 1000MB lvm1 lvm
4 4295MB 5369MB 1074MB ext2 lvm2 lvm
(parted) quit
Information: You may need to update /etc/fstab.
Create Physical Volume (pvcreate)
To create the underlying physical volume, we use the pvcreate command and specify the partition we want to use.
[root@tst-rhel ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 50G 0 disk
├─xvda1 202:1 0 1M 0 part
└─xvda2 202:2 0 50G 0 part /
xvdb 202:16 0 10G 0 disk
├─xvdb1 202:17 0 953M 0 part
├─xvdb2 202:18 0 954M 0 part [SWAP]
├─xvdb3 202:19 0 954M 0 part
└─xvdb4 202:20 0 1G 0 part
xvdc 202:32 0 9G 0 disk
[root@tst-rhel ~]# pvcreate /dev/xvdb3
Physical volume "/dev/xvdb3" successfully created.
To view all available physical volume groups, use pvs. You'll notice that under the VG column, none is specified. This indicates that this PVG is not yet assigned to a volume group.
[root@tst-rhel ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/xvdb3 lvm2 --- 954.00m 954.00m
Assigning the PV to a VG (vgcreate)
To assign a physical volume group to a volume group (VG), use Vgcreate followed by the name of the volume group. Running pvs again will show a value under the VG column, indicating that the PVG is now associated with a VG.
[root@tst-rhel ~]# vgcreate vgdata /dev/xvdb3
Volume group "vgdata" successfully created
[root@tst-rhel ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/xvdb3 vgdata lvm2 a-- 952.00m 952.00m
[root@tst-rhel ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vgdata 1 0 0 wz--n- 952.00m 952.00m
Create Logical Volume Group (lvcreate)
To create a logical volume group (LVM), execute lvcreate with the -n flag followed by the name of the LVM group and the size of the VG previously created. Ensure the name of the volume group is specified correctly for it to be detected.
[root@tst-rhel ~]# lvcreate -n lvdata -L 952M VGDATA
Volume group "VGDATA" not found
Cannot process volume group VGDATA
[root@tst-rhel ~]# lvcreate -n lvdata -L 952M vgdata
Logical volume "lvdata" created.
To check the physical volume group, volume group, and LVG:
[root@tst-rhel ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/xvdb3 vgdata lvm2 a-- 952.00m 0
[root@tst-rhel ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vgdata 1 1 0 wz--n- 952.00m 0
[root@tst-rhel ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lvdata vgdata -wi-a----- 952.00m
Make a filesystem
To avoid confusion, it's always a good practice to run lsblk first. Here, we can see the LVM named vgdata-lvdata under xvdb.
[root@tst-rhel ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 50G 0 disk
├─xvda1 202:1 0 1M 0 part
└─xvda2 202:2 0 50G 0 part /
xvdb 202:16 0 10G 0 disk
├─xvdb1 202:17 0 953M 0 part
├─xvdb2 202:18 0 954M 0 part [SWAP]
├─xvdb3 202:19 0 954M 0 part
│ └─vgdata-lvdata 253:0 0 952M 0 lvm
└─xvdb4 202:20 0 1G 0 part
xvdc 202:32 0 9G 0 disk
When we create the file system, we'll use the path '/dev/vgname/lvname':
[root@tst-rhel ~]# mkfs -t xfs /dev/vgdata/lvdata
meta-data=/dev/vgdata/lvdata isize=512 agcount=4, agsize=60928 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=243712, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=1566, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
Mount it
After creating the LVM and file system, it's time to create the directory that will serve as the mount point. To make this mount persistent across reboots, we need to add an entry to /etc/fstab.
[root@tst-rhel ~]# mkdir /mnt/diskblvm
[root@tst-rhel ~]# ll /mnt/
total 0
drwxr-xr-x. 2 root root 6 Dec 7 15:21 diskb1
drwxr-xr-x. 2 root root 6 Dec 31 14:50 diskblvm
[root@tst-rhel ~]# vim /etc/fstab
UUID=d35fe619-1d06-4ace-9fe3-169baad3e421 / xfs defaults 0 0
UUID=e6bcc068-628c-4555-b06e-9cda9563cf8c swap swap defaults 0 0
# SWAP
/dev/xvdb2 swap swap defaults 0 0
# LVM
/dev/vgdata/lvdata /mnt/diskblvm xfs defaults 0 0
Finally, mount it:
[root@tst-rhel ~]# mount -a
[root@tst-rhel ~]# mount | grep vgdata
/dev/mapper/vgdata-lvdata on /mnt/diskblvm type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)
Another useful command to see the mounts in tree-form is findmnt:
[root@tst-rhel ~]# findmnt
TARGET SOURCE FSTYPE OPTIONS
/ /dev/xvda2 xfs rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota
├─/sys sysfs sysfs rw,nosuid,nodev,noexec,relatime,seclabel
│ ├─/sys/kernel/security securityfs securityfs rw,nosuid,nodev,noexec,relatime
│ ├─/sys/fs/cgroup tmpfs tmpfs ro,nosuid,nodev,noexec,seclabel,mode=755
│ │ ├─/sys/fs/cgroup/systemd cgroup cgroup rw,nosuid,nodev,noexec,relatime,seclabel,xattr,release_agent=/usr
│ │ ├─/sys/fs/cgroup/cpu,cpuacct cgroup cgroup rw,nosuid,nodev,noexec,relatime,seclabel,cpu,cpuacct
│ ├─/sys/kernel/debug debugfs debugfs rw,relatime,seclabel
│ └─/sys/kernel/config configfs configfs rw,relatime
├─/proc proc proc rw,nosuid,nodev,noexec,relatime
│ └─/proc/sys/fs/binfmt_misc systemd-1 autofs rw,relatime,fd=42,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,p
├─/dev devtmpfs devtmpfs rw,nosuid,seclabel,size=8067292k,nr_inodes=2016823,mode=755
│ ├─/dev/shm tmpfs tmpfs rw,nosuid,nodev,seclabel
│ ├─/dev/pts devpts devpts rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000
│ ├─/dev/hugepages hugetlbfs hugetlbfs rw,relatime,seclabel,pagesize=2M
│ └─/dev/mqueue mqueue mqueue rw,relatime,seclabel
├─/run tmpfs tmpfs rw,nosuid,nodev,seclabel,mode=755
│ └─/run/user/1000 tmpfs tmpfs rw,nosuid,nodev,relatime,seclabel,size=1620980k,mode=700,uid=1000
├─/var/lib/nfs/rpc_pipefs rpc_pipefs rpc_pipefs rw,relatime
├─/tmp tmpfs tmpfs rw,nosuid,nodev,seclabel
└─/mnt/diskblvm /dev/mapper/vgdata-lvdata
xfs rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota