HOW TO CREATE LVM USING PVCREATE, VGCREATE, LVCREATE, AND LVEXTEND COMMANDS
What is LVM?
LVM is a tool for logical volume management which includes allocating disks, striping, mirroring and resizing logical volumes. With LVM, a hard drive or set of hard drives is allocated to one or more physical volumes.
How to setup LVM in RHEL 7
Once the physical disk space has been made available to the host, run the following command to identify the disk location:
fdisk -l
Disk /dev/sdb: 4294 MB, 4294967296 bytes, 8388608 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x5eee65f8
The output of the above command identifies the location of the 4 GB disk as being located in /dev/sdb. The next step involves issuing the following command (replace /dev/sdv with the output you receive from the above command):
[root@slave ~]# fdisk /dev/sdb
Typ Type n to create a new partition and press enter three times until you reach the Last sector prompt. Enter +4GB here and press enter. Type in w and press enter to make the changes live. Issuing partprobe makes the partition live without rebooting the host.
[root@slave ~]# partprobe
The next step involves creating a physical volume.
[root@slave ~]# pvcreate /dev/sdb1
Physical volume “/dev/sdb1” successfully created
Run a pvscan to pickup the changes.
[root@slave ~]# pvscan
PV /dev/sda2 VG rhel lvm2 [7.51 GiB / 0 free]
Total: 1 [7.51 GiB] / in use: 1 [7.51 GiB] / in no VG: 0 [0 ]
We now need to create a volume group.
[root@slave ~]# vgcreate roldy /dev/sdb1
Volume group “roldy” successfully created
Inside of this volume group, we will now create a logical partition.
[root@slave ~]# lvcreate roldy –name snookicoco /dev/sdb1 -L 200MB
Logical volume “snookicoco” created
Format the file system with xfs using the below command:
[root@slave ~]# mkfs.xfs /dev/roldy/snookicoco
meta-data=/dev/roldy/snookicoco isize=256 agcount=4, agsize=12800 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=51200, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
Create a folder on the host which will be mapped to this storage:
[root@slave ~]# mkdir /snookicoco
In order to edit the fstab, we will need to obtain the UUID of the volume. The UUID can be easily obtained via the blkid command.
[root@slave ~]# blkid
/dev/sda1: UUID=”46814065-a338-4860-a3f8-781b132987c6″ TYPE=”xfs”
/dev/sda2: UUID=”3gzDCV-lPFf-8hKA-Kojk-XI01-T7SR-xfK8fd” TYPE=”LVM2_member”
/dev/sdb1: UUID=”QCrBPH-KPEw-PZ3c-xDs0-nUVE-esuL-AZorqV” TYPE=”LVM2_member”
/dev/mapper/rhel-root: UUID=”dddea344-415f-4b2b-811f-8d7eac492f9e” TYPE=”xfs”
/dev/mapper/rhel-swap: UUID=”e7128c41-27b0-45ad-8f20-ddf7ce444aa1″ TYPE=”swap”
/dev/mapper/roldy-snookicoco: UUID=”ae3cc85c-158f-4075-9025-5db0998c1d73″ TYPE=”xfs”
It’s now time to mount the partition using the fstab.
[root@slave ~]# vi /etc/fstab
Copy the UUID across to a new line in the fstab, add the local mount point and specify the file system as per the below entry:
# /etc/fstab
# Created by anaconda on Thu Sep 18 00:41:01 2014
#
# Accessible filesystems, by reference, are maintained under ‘/dev/disk’
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/rhel-root / xfs defaults 1 1
UUID=46814065-a338-4860-a3f8-781b132987c6 /boot xfs defaults 1 2
/dev/mapper/rhel-swap swap swap defaults 0 0
UUID=”ae3cc85c-158f-4075-9025-5db0998c1d73″ /snookicoco xfs defaults 1 2
~
~
Verify that the mount point is now listed.
[root@slave ~]# df -hk | grep snookicoco
/dev/mapper/roldy-snookicoco 201388 10400 190988 6% /snookicoco
How to extend a logical volume
Extending logical volumes is possible thanks to the lvextend utility.
lvextend -L +500M /dev/coco/chops
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