How To Manage LVM in Debian
To Manage the Logical Volume in Debian Linux.
Installation of Logical Volume Management with the procedure to manage multiple disks and partitions will be discussed in this article.
To Install LVM on Debian
Root access is required to manage logical volumes. Use ' su' or ' sudo' command to achieve it.
Run the following command to install lvm2 package.
root@linuxhelp:~# apt-get install lvm2
Reading package lists... Done
Building dependency tree
Reading state information... Done
Suggested packages:
thin-provisioning-tools
The following NEW packages will be installed:
lvm2
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Setting up lvm2 (2.02.111-2.2) ...
update-initramfs: deferring update (trigger activated)
update-rc.d: warning: start and stop actions are no longer supported falling back to defaults
Processing triggers for initramfs-tools (0.120) ...
update-initramfs: Generating /boot/initrd.img-3.16.0-4-amd64
Run the below command check the installed package.
root@linuxhelp:~# dpkg-query -s lvm2
Package: lvm2
Status: install ok installed
Priority: optional
Section: admin
Installed-Size: 1624
Maintainer: Debian LVM Team < pkg-lvm-maintainers@lists.alioth.debian.org>
Architecture: amd64
Multi-Arch: foreign
Version: 2.02.111-2.
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Description: Linux Logical Volume Manager
This is LVM2, the rewrite of The Linux Logical Volume Manager. LVM
supports enterprise level volume management of disk and disk subsystems
by grouping arbitrary disks into volume groups. The total capacity of
volume groups can be allocated to logical volumes, which are accessed as
regular block devices.
Homepage: http://sources.redhat.com/lvm2/
root@linuxhelp:~# dpkg-query -l lvm2
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-============-============-=================================
ii lvm2 2.02.111-2.2 amd64 Linux Logical Volume Manager
In general, LVM partition will be done by using basic tools like, cfdisk, fdisk, gparted and parted to partition and also flag the partitions to use in a LVM setup. We have 3 partition in hard disk namely sda1, sda2, sda3 and is used by the system OS. Now we have created a new partition sda5 for LVM.
root@linuxhelp:~# pvcreate /dev/sda5
Physical volume " /dev/sda5" successfully created
Now the physical volume is created to /dev/sda5.
To add Volume Group
Run the following command to add a Volume Group ' vg1' .
root@linuxhelp:~# vgcreate vg1 /dev/sda5
Volume group " vg1" successfully created
In the above command the first argument is the name of the Volume Group we have created and the second will be the name of the RAID device created using pvcreate in /dev/sda5.
Run the following command to verify the Volume group.
root@linuxhelp:~# vgdisplay --- Volume group --- VG Name vg1 System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 1 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 1 Act PV 1 VG Size 10.00 GiB PE Size 4.00 MiB Total PE 2559 Alloc PE / Size 0 / 0 Free PE / Size 2559 / 10.00 GiB VG UUID ei17xi-hJwh-te62-mzQJ-1Pfd-UkFY-dLTEXH root@linuxhelp:~# vgs VG #PV #LV #SN Attr VSize VFree vg1 1 0 0 wz--n- 10.00g 10.00g
Now we can start creating the Logical Volumes inside the Volume Groups.
Run the following command to create the Logical Volume (LV)
root@linuxhelp:~# lvcreate -L 5G -n lv1 vg1
Logical volume " lv1" created
Explanation,
-L size of the LV,
-n the name of the LV.
Now create another Logical Volume, by using the following command.
root@linuxhelp:~# lvcreate -L 4G -n lv2 vg1
Logical volume " lv2" created
Verify the creation of the LV , by using either of the following commands:
-lvdisplay gives you the detailed output of the Logical Volumes.
-lvs gives you Less detailed output of the Logical Volumes.
Here, we are running lvdisplay command to get a detailed output.
root@linuxhelp:~# lvdisplay --- Logical volume --- LV Path /dev/vg1/people LV Name lv1 VG Name vg1 LV UUID 4ElP60-SBxa-1pzd-IcLJ-TTRv-MPHx-RrfB8n LV Write Access read/write LV Creation host, time linuxhelp, 2016-04-20 18:20:31 +0530 LV Status available # open 0 LV Size 5.00 GiB Current LE 1280 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 254:0 --- Logical volume --- LV Path /dev/vg1/lv2 LV Name lv2 VG Name vg1 LV UUID 4ySeJI-Iyyk-a72g-Upgy-tztg-PyVP-ghivNM LV Write Access read/write LV Creation host, time linuxhelp, 2016-04-20 18:21:30 +0530 LV Status available # open 0 LV Size 4.00 GiB Current LE 1024 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 254:1 [root@linuxhelp:~#] lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv1 vg1 -wi-a----- 5.00g lv2 vg1 -wi-a----- 4.00g
The LV' s are configured, but it is not ready to mount and use. Format the LV with a file-system using gparted or mkfs.
Here we use CLI server, so the mkfs utility is used to accomplish this task.
root@linuxhelp:~# mkfs.ext4 -L lv1 /dev/vg1/lv1
mke2fs 1.42.12 (29-Aug-2014)
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Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
root@linuxhelp:~# mkfs.ext4 -L lv2 /dev/vg1/lv2
mke2fs 1.42.12 (29-Aug-2014)
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Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
The above commands will write an ext4 file system to each of the LV created under the file system label (-L) on each of the LV file systems.
To create a directory
Create a new directory for each Logical Volumes, using the following command.
root@linuxhelp:~# mkdir /mnt/test
root@linuxhelp:~# mkdir /mnt/test1
Now mount the logical volumes to the new directories created using the below commands.
root@linuxhelp:~# mount /dev/vg1/lv1 /mnt/test
root@linuxhelp:~# mount /dev/vg1/lv2 /mnt/test1
The LV' s are ready to use in the directory ' /mnt/test' or ' /mnt/test1' , confirm it using the lsblk command.
root@linuxhelp:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 30G 0 disk
??sda1 8:1 0 9.3G 0 part /
??sda2 8:2 0 3.7G 0 part [SWAP]
??sda5 8:5 0 10G 0 part
??vg1-lv1 254:0 0 5G 0 lvm /mnt/test
??vg1-lv2 254:1 0 4G 0 lvm /mnt/test1
sr0 11:0 1 3.7G 0 rom /media/cdrom0
To get Universally Unique Identifier (UUID)
Run the following command to obtain the Universally Unique Identifier value and also the file system type, which is required to use, to start, to setup persistent mounting.
root@linuxhelp:~# blkid /dev/vg1/*
/dev/vg1/lv1: LABEL=" lv1" UUID=" e88e067c-bf1b-462a-a04b-b48bb93b1a09" TYPE=" ext4"
/dev/vg1/lv2: LABEL=" lv2" UUID=" 594881b0-a9e4-4867-b6a7-5450a6f278de" TYPE=" ext4"
The above UUID values for each of the LVs created must be sent to ' /etc/fstab' and this can be achieved by running the following command.
root@linuxhelp:~# blkid /dev/vg1/* > > /etc/fstab
Make sure, this command uses > > (DOUBLE greater than symbols). If suppose > (a single greater than symbol) is used, the contents of the file will be over-written.
To open the /etc/fstab file with a text editor run the following command.
root@linuxhelp:~# vim /etc/fstab
# /etc/fstab: static file system information.
#
# Use ' blkid' to print the universally unique identifier for a
# device this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
#
# / was on /dev/sda1 during installation
UUID=678bde07-b627-4113-b332-038322a15465 / ext4 errors=remount-ro 0 1
# swap was on /dev/sda2 during installation
UUID=6251a6f5-b5f4-428d-bcc0-23e90a0b5e11 none swap sw 0 0
/dev/sr0 /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/vg1/lv1: LABEL=" lv1" UUID=" e88e067c-bf1b-462a-a04b-b48bb93b1a09" TYPE=" ext4"
/dev/vg1/lv2: LABEL=" lv2" UUID=" 594881b0-a9e4-4867-b6a7-5450a6f278de" TYPE=" ext4"
To format the /etc/fstab file remove ' /dev/vg1/lv1' and ' /dev/vg1/lv2' . Enter the mount points and the absolute path to the mount point in the field should be placed after the UUID.
The third field, should be the file system, ' ext4' and fourth field is set as ' defaults' and the last two (< dump> < pass> ) will be set as zeros.
# /etc/fstab: static file system information. # # Use ' blkid' to print the universally unique identifier for a # device this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # # / was on /dev/sda1 during installation UUID=678bde07-b627-4113-b332-038322a15465 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda2 during installation UUID=6251a6f5-b5f4-428d-bcc0-23e90a0b5e11 none swap sw 0 0 /dev/sr0 /media/cdrom0 udf,iso9660 user,noauto 0 0 UUID=e88e067c-bf1b-462a-a04b-b48bb93b1a09 /mnt/test ext4 defaults 0 0 UUID=594881b0-a9e4-4867-b6a7-5450a6f278de /mnt/test1 ext4 defaults 0 0 ~
To confirm the mount points, use the ' mount' command with an argument which allows the mount utility to load all the mounts automatically.
root@linuxhelp:~# mount -a
To check the above process, run lsblk command.
root@linuxhelp:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 30G 0 disk
??sda1 8:1 0 9.3G 0 part /
??sda2 8:2 0 3.7G 0 part [SWAP]
??sda5 8:5 0 10G 0 part
??vg1-lv1 254:0 0 5G 0 lvm /mnt/test
??vg1-lv2 254:1 0 4G 0 lvm /mnt/test1
sr0 11:0 1 3.7G 0 rom /media/cdrom0
Here the LVs are accessible through /mnt/test and /mnt/test1 for the system user to migrate the data, re-sizing the data or add more data using LVM volumes.