Overview
By the end of this article you should be able to answer the following questions:
Announcement
I have released my new course on Udemy, Kubernetes By Example. Sign up now to get free lifetime access!What is the command to create a partition from /dev/sdb?
$ fdisk /dev/sdb
What is the command to create a PV from /dev/sdb1?
$ pvcreate /dev/sdb1
What is the command to create a VG with the name vgdata1vg from the PV, /dev/sdb1?
$ vgcreate vgdata1vg /dev/sdb1
What is the command to create a 300MB LV (called lvmyfirstlv) from the VG, vgdata1vg?
$ lvcreate -n lvmyfirstlv -L 300M vgdata1vg
What are the 2 symbolic links that are created under the /dev directory after running the above command?
/dev/mapper/vgdata1vg-lvmyfirstlv # i.e. /dev/mapper/{vgname}-{lvname}
# and:
/dev/vgdata1vg/lvmyfirstlv # i.e. /dev/{vg-name}/{lv-name}
What is the command to install the ext4 filesystem on LV, lvmyfirstlv, which was created from the VG, vgdata1vg?
$ mkfs.ext4 /dev/vgdata1vg/lvmyfirstlv
What is the command for creating the mountpoint, /tmp/lvdata1?
$ mkdir /tmp/lvdata1
What is the command for manually mounting the LV, /dev/vgdata1vg/lvmyfirstlv onto the mountpoint /tmp/lvdata1?
$ mount /dev/vgdata1vg/lvmyfirstlv /tmp/lvdata1
What is the entry you need to add to the /etc/fstab file to automount this logical volumen at boot time?
/dev/vgdata1vg/lvmyfirstlv /tmp/lvdata1 ext4 defaults 0 0
What is the command to check that the above entry is correct?
$ mount -a
What are the 3 commands to check that filesystem has been mounted?
$ df -h # this lists all active filesystems
# or
$ lsblk
# or
$ mount
To understand how to create a Logical Volume, it’s best to walk through a scenario:
Scenario
In this scenario we have attached a new 2GB hdd to our machine (/dev/sdb), and we now want to do the following:
- We want to create 3 partitions on this hdd, of which the second and third partitions are going to be used as part of LVM. The 1st partition will be 1GB in size, whereas the 2nd and 3rd partition will be 500MB each.
- Create Physical Volumes out of partitions 2 and 3.
- We will create a new volume group, which will comprise of the 2nd and 3rd partitions.
- We will then create 2 logical volumes from this volume group.
- The first lv will have the xfs filesystem installed on it. And the second will have the ext4 filesystem installed on it.
- These logical volume then needs to be mounted and be available for use
Create partitions to be used for LVM
Right now we just have the 2GB hdd with no partitions:
$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk sr0 11:0 1 55.4M 0 rom
Now let’s use fdisk to create the 3 partitions:
$ fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-4310167, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-4310167, default 4310167): +1100M
Partition 1 of type Linux and of size 1.1 GiB is set
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p
Partition number (2-4, default 2):
First sector (2254848-4310167, default 2254848):
Using default value 2254848
Last sector, +sectors or +size{K,M,G} (2254848-4310167, default 4310167): +500M
Partition 2 of type Linux and of size 500 MiB is set
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): p
Partition number (3,4, default 3):
First sector (3278848-4310167, default 3278848):
Using default value 3278848
Last sector, +sectors or +size{K,M,G} (3278848-4310167, default 4310167):
Using default value 4310167
Partition 3 of type Linux and of size 503.6 MiB is set
Command (m for help): p
Disk /dev/sdb: 2206 MB, 2206806016 bytes, 4310168 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: 0xf1258b4b
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2254847 1126400 83 Linux
/dev/sdb2 2254848 3278847 512000 83 Linux
/dev/sdb3 3278848 4310167 515660 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 19.5G 0 part
├─centos-swap 253:0 0 2G 0 lvm [SWAP]
└─centos-root 253:1 0 17.5G 0 lvm /
sdb 8:16 0 2.1G 0 disk
├─sdb1 8:17 0 1.1G 0 part
├─sdb2 8:18 0 500M 0 part
└─sdb3 8:19 0 503.6M 0 part
sr0 11:0 1 55.4M 0 rom
As you can see we have now created 3 partitions. However partitions 2 and 3 are currently listed as standard Linux partitions (type 83) as highlighted above. Therefore we need to switch this to the LVM partition type:
$ fdisk /dev/sdb Welcome to fdisk (util-linux 2.23.2). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): m Command action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition g create a new empty GPT partition table G create an IRIX (SGI) partition table l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only) Command (m for help): t Partition number (1-3, default 3): 2 Hex code (type L to list all codes): L 0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris 1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT- 2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT- 3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT- 4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx 5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data 6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / . 7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility 8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt 9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT f W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/ 10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b 11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor 12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor 14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary 16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS 17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE 18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto 1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep 1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT 1e Hidden W95 FAT1 80 Old Minix Hex code (type L to list all codes): 8e Changed type of partition 'Linux' to 'Linux LVM' Command (m for help): t Partition number (1-3, default 3): Hex code (type L to list all codes): 8e Changed type of partition 'Linux' to 'Linux LVM' Command (m for help): p Disk /dev/sdb: 2206 MB, 2206806016 bytes, 4310168 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: 0xf1258b4b Device Boot Start End Blocks Id System /dev/sdb1 2048 2254847 1126400 83 Linux /dev/sdb2 2254848 3278847 512000 8e Linux LVM /dev/sdb3 3278848 4310167 515660 8e Linux LVM Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
We have now created the 3 partitions and allocated partions 2 and 3 for LVM usage. This now means that we can create physical volumes out of partitions 2 and 3.
Create physical volumes
There are a few commands available for doing pv related tasks:
$ pv pvchange pvck pvcreate pvdisplay pvmove pvremove pvresize pvs pvscan
Let’s list all the pvs that currently exists:
$ pvs PV VG Fmt Attr PSize PFree /dev/sda2 centos lvm2 a-- 19.51g 0
Note: The “pvdislay” command also shows pretty much the same info.
As you can see, /dev/sdb2 and /dev/sdb3 are not listed here. To create PVs, we use the pvcreate command:
$ pvcreate --help
pvcreate: Initialize physical volume(s) for use by LVM
pvcreate
[--norestorefile]
[--restorefile file]
[--commandprofile ProfileName]
[-d|--debug]
[-f[f]|--force [--force]]
[-h|-?|--help]
[--labelsector sector]
[-M|--metadatatype 1|2]
[--pvmetadatacopies #copies]
[--bootloaderareasize BootLoaderAreaSize[bBsSkKmMgGtTpPeE]]
[--metadatasize MetadataSize[bBsSkKmMgGtTpPeE]]
[--dataalignment Alignment[bBsSkKmMgGtTpPeE]]
[--dataalignmentoffset AlignmentOffset[bBsSkKmMgGtTpPeE]]
[--setphysicalvolumesize PhysicalVolumeSize[bBsSkKmMgGtTpPeE]
[-t|--test]
[-u|--uuid uuid]
[-v|--verbose]
[-y|--yes]
[-Z|--zero {y|n}]
[--version]
PhysicalVolume [PhysicalVolume...]
Let’s now initialize the 2nd and 3rd partitions into physical volumes now:
$ pvcreate /dev/sdb2 Physical volume "/dev/sdb2" successfully created $ pvcreate /dev/sdb3 Physical volume "/dev/sdb3" successfully created $ pvs PV VG Fmt Attr PSize PFree /dev/sda2 centos lvm2 a-- 19.51g 0 /dev/sdb2 lvm2 --- 500.00m 500.00m /dev/sdb3 lvm2 --- 503.57m 503.57m
Now we have 2 physical volumes, but they haven’t been added to a VG yet, hence the empty fields under the VG column.
Create volume group
There are a few commands available for doing vg related tasks:
$ vg vgcfgbackup vgck vgdisplay vgimport vgmknodes vgrename vgsplit vgcfgrestore vgconvert vgexport vgimportclone vgreduce vgs vgchange vgcreate vgextend vgmerge vgremove vgscan
Let’s see what vg currently exists using the vgs command:
$ vgs VG #PV #LV #SN Attr VSize VFree centos 1 2 0 wz--n- 19.51g 0
Now to create a new vg, we use the vgcreate command:
vgcreate --help
vgcreate: Create a volume group
vgcreate
[-A|--autobackup {y|n}]
[--addtag Tag]
[--alloc AllocationPolicy]
[-c|--clustered {y|n}]
[--commandprofile ProfileName]
[-d|--debug]
[-h|--help]
[-l|--maxlogicalvolumes MaxLogicalVolumes]
[--metadataprofile ProfileName]
[-M|--metadatatype 1|2]
[--[vg]metadatacopies #copies]
[-p|--maxphysicalvolumes MaxPhysicalVolumes]
[-s|--physicalextentsize PhysicalExtentSize[bBsSkKmMgGtTpPeE]]
[-t|--test]
[-v|--verbose]
[--version]
[-y|--yes]
[ PHYSICAL DEVICE OPTIONS ]
VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
Let’s now create our new vg, “vgdata1vg”, but for demonstration purposes, we’ll only add one physical volume initially:
$ vgcreate vgdata1vg /dev/sdb2 Volume group "vgdata1vg" successfully created
Let’s now confirm that our vg now exists:
$ vgs VG #PV #LV #SN Attr VSize VFree centos 1 2 0 wz--n- 19.51g 0 vgdata1vg 1 0 0 wz--n- 496.00m 496.00m
Notice here that it gives info that our vg is only made up of 1 PV so far, and that no LV have been created from vgdata1vg. The vgs command is really useful because it gives you a nice overall LVM status.
Now that our vg exists, to add the other pv to our vg, we need to use the vgextend command:
$ vgextend --help
vgextend: Add physical volumes to a volume group
vgextend
[-A|--autobackup y|n]
[--restoremissing]
[--commandprofile ProfileName]
[-d|--debug]
[-f|--force]
[-h|--help]
[-t|--test]
[-v|--verbose]
[--version]
[-y|--yes]
[ PHYSICAL DEVICE OPTIONS ]
VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
Therfore let’s add sdb3 to vgdata1vg right now:
$ vgextend vgdata1vg /dev/sdb3 Volume group "vgdata1vg" successfully extended $ vgs VG #PV #LV #SN Attr VSize VFree centos 1 2 0 wz--n- 19.51g 0 vgdata1vg 2 0 0 wz--n- 996.00m 996.00m
This has now worked. Notice that total disk space is about 4MB less than the 1GB that was expected. That’s becuase that 4MB is used by LVM internally for metadata purposes.
If we now run the pvs command now, we’ll see that both PVs are now attached to our new VG:
$ pvs PV VG Fmt Attr PSize PFree /dev/sda2 centos lvm2 a-- 19.51g 0 /dev/sdb2 vgdata1vg lvm2 a-- 496.00m 496.00m /dev/sdb3 vgdata1vg lvm2 a-- 500.00m 500.00m
Create Logical Volumes
There are a few commands available for doing lv related tasks:
$ lv lvchange lvdisplay lvmchange lvmdump lvmsar lvrename lvscan lvconvert lvextend lvmconf lvmetad lvreduce lvresize lvcreate lvm lvmdiskscan lvmsadc lvremove lvs
Let’s see what LVs currently exists using the lvs command:
$ lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root centos -wi-ao---- 17.51g swap centos -wi-ao---- 2.00g
These LVs are also represented in the form of files, under /dev/mapper:
$ ls -l /dev/mapper/ total 0 lrwxrwxrwx. 1 root root 7 May 22 18:39 centos-root -> ../dm-1 lrwxrwxrwx. 1 root root 7 May 22 18:39 centos-swap -> ../dm-0 crw-------. 1 root root 10, 236 May 22 18:39 control
As you can see the naming convention of these files are “vgname-lvname”
Now to create LVs, we need to use the lvcreate command:
$ lvcreate --help
lvcreate: Create a logical volume
lvcreate
[-A|--autobackup {y|n}]
[-a|--activate [a|e|l]{y|n}]
[--addtag Tag]
[--alloc AllocationPolicy]
[-H|--cache
[--cachemode {writeback|writethrough}]
[--cachepool CachePoolLogicalVolume{Name|Path}]
[-c|--chunksize ChunkSize]
[-C|--contiguous {y|n}]
[--commandprofile ProfileName]
[-d|--debug]
[-h|-?|--help]
[--errorwhenfull {y|n}]
[--ignoremonitoring]
[--monitor {y|n}]
[-i|--stripes Stripes [-I|--stripesize StripeSize]]
[-k|--setactivationskip {y|n}]
[-K|--ignoreactivationskip]
{-l|--extents LogicalExtentsNumber[%{VG|PVS|FREE}] |
-L|--size LogicalVolumeSize[bBsSkKmMgGtTpPeE]}
[-M|--persistent {y|n}] [-j|--major major] [--minor minor]
[--metadataprofile ProfileName]
[-m|--mirrors Mirrors [--nosync]
[{--mirrorlog {disk|core|mirrored}|--corelog}]]
[-n|--name LogicalVolumeName]
[--noudevsync]
[-p|--permission {r|rw}]
[--poolmetadatasize MetadataSize[bBsSkKmMgG]]
[--poolmetadataspare {y|n}]]
[--[raid]minrecoveryrate Rate]
[--[raid]maxrecoveryrate Rate]
[-r|--readahead {ReadAheadSectors|auto|none}]
[-R|--regionsize MirrorLogRegionSize]
[-T|--thin
[--discards {ignore|nopassdown|passdown}]
[--thinpool ThinPoolLogicalVolume{Name|Path}]
[-t|--test]
[--type VolumeType]
[-v|--verbose]
[-W|--wipesignatures {y|n}]
[-Z|--zero {y|n}]
[--version]
VolumeGroupName [PhysicalVolumePath...]
.
.
.
The important options are highlighted above. Based on the help info, let’s now create our new LVs:
$ lvcreate -n lvmyfirstlv -L 300M vgdata1vg Logical volume "lvmyfirstlv" created. $ lvcreate -n lvmysecondlv -L 400M vgdata1vg Logical volume "lvmysecondlv" created.
Let’s now confirm that this has worked:
$ lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root centos -wi-ao---- 17.51g swap centos -wi-ao---- 2.00g lvmyfirstlv vgdata1vg -wi-a----- 300.00m lvmysecondlv vgdata1vg -wi-a----- 400.00m
And also:
$ vgs VG #PV #LV #SN Attr VSize VFree centos 1 2 0 wz--n- 19.51g 0 vgdata1vg 2 2 0 wz--n- 996.00m 296.00m
Also the following files have been created:
$ ls -l /dev/mapper/ total 0 lrwxrwxrwx. 1 root root 7 May 22 18:39 centos-root -> ../dm-1 lrwxrwxrwx. 1 root root 7 May 22 18:39 centos-swap -> ../dm-0 crw-------. 1 root root 10, 236 May 22 18:39 control lrwxrwxrwx. 1 root root 7 May 22 22:30 vgdata1vg-lvmyfirstlv -> ../dm-2 lrwxrwxrwx. 1 root root 7 May 22 22:31 vgdata1vg-lvmysecondlv -> ../dm-3 $ ls -l /dev/ | egrep "dm-2|dm-3" brw-rw----. 1 root disk 253, 2 May 22 22:30 dm-2 brw-rw----. 1 root disk 253, 3 May 22 22:31 dm-3
We also have the following symbolic links that points to the same block devices as well:
$ ls -l /dev | grep vgdata1vg drwxr-xr-x. 2 root root 80 May 22 22:31 vgdata1vg $ ls -l /dev/vgdata1vg total 0 lrwxrwxrwx. 1 root root 7 May 22 22:30 lvmyfirstlv -> ../dm-2 lrwxrwxrwx. 1 root root 7 May 22 22:31 lvmysecondlv -> ../dm-3
As you can see we have 2 sets of symbolic links pointing to the same block files. The naming convention this time is:
/dev/{vg-name}/{lv-name}
These symbolic links are designed to make our lives easier when we want to refer to a particular LV. These symbolic links becomes useful when we come to installing filesystems and mounting our LVs.
It doesn’t matter which symbolic links you use, as long as you are comfortable with them.
Install file system onto logical volumes
Just before we start installing file system’s let’s take a look at the current status:
lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk ├─sdb1 8:17 0 1.1G 0 part ├─sdb2 8:18 0 500M 0 part │ └─vgdata1vg-lvmyfirstlv 253:2 0 300M 0 lvm └─sdb3 8:19 0 503.6M 0 part └─vgdata1vg-lvmysecondlv 253:3 0 400M 0 lvm sr0 11:0 1 55.4M 0 rom [root@localhost /]# blkid /dev/sr0: UUID="2015-03-02-14-24-20-00" LABEL="VBOXADDITIONS_4.3.24_98716" TYPE="iso9660" /dev/sda1: UUID="547c78ce-34b5-4e31-84d2-bf72b196fa57" TYPE="xfs" /dev/sda2: UUID="JnfbeO-XPAG-AS0O-Mrtw-hnwn-7hqf-Mhk46t" TYPE="LVM2_member" /dev/mapper/centos-swap: UUID="94263d84-5357-4566-9987-fc74ca946a96" TYPE="swap" /dev/mapper/centos-root: UUID="17f09dae-88d1-4813-9738-8996819cf6ba" TYPE="xfs" /dev/sdb2: UUID="rWS5kI-EvQy-C1yO-S1C2-QJeP-i52B-XhNRZ0" TYPE="LVM2_member" /dev/sdb3: UUID="iwFLr7-fDHl-wdnT-mwKU-FSKq-xdEH-GcrnGD" TYPE="LVM2_member"
Now let’s install the ext4 filesystem on the first LV:
$ mkfs.ext4 /dev/vgdata1vg/lvmyfirstlv
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
76912 inodes, 307200 blocks
15360 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=33947648
38 block groups
8192 blocks per group, 8192 fragments per group
2024 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729, 204801, 221185
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
Now lets install the xfs filesystem on the second LV:
$ mkfs.xfs /dev/mapper/vgdata1vg-lvmysecondlv
meta-data=/dev/mapper/vgdata1vg-lvmysecondlv isize=256 agcount=4, agsize=25600 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=102400, 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
Now let’s recheck the status:
$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk ├─sdb1 8:17 0 1.1G 0 part ├─sdb2 8:18 0 500M 0 part │ └─vgdata1vg-lvmyfirstlv 253:2 0 300M 0 lvm └─sdb3 8:19 0 503.6M 0 part └─vgdata1vg-lvmysecondlv 253:3 0 400M 0 lvm sr0 11:0 1 55.4M 0 rom $ blkid /dev/sr0: UUID="2015-03-02-14-24-20-00" LABEL="VBOXADDITIONS_4.3.24_98716" TYPE="iso9660" /dev/sda1: UUID="547c78ce-34b5-4e31-84d2-bf72b196fa57" TYPE="xfs" /dev/sda2: UUID="JnfbeO-XPAG-AS0O-Mrtw-hnwn-7hqf-Mhk46t" TYPE="LVM2_member" /dev/mapper/centos-swap: UUID="94263d84-5357-4566-9987-fc74ca946a96" TYPE="swap" /dev/mapper/centos-root: UUID="17f09dae-88d1-4813-9738-8996819cf6ba" TYPE="xfs" /dev/sdb2: UUID="rWS5kI-EvQy-C1yO-S1C2-QJeP-i52B-XhNRZ0" TYPE="LVM2_member" /dev/sdb3: UUID="iwFLr7-fDHl-wdnT-mwKU-FSKq-xdEH-GcrnGD" TYPE="LVM2_member" /dev/mapper/vgdata1vg-lvmyfirstlv: UUID="c35e024a-fd04-45de-afc8-566c634593cd" TYPE="ext4" /dev/mapper/vgdata1vg-lvmysecondlv: UUID="02e140d7-0323-40d2-b7ee-5728f06305e3" TYPE="xfs"
As you can see, our new block devices (which are the file representation of our logical volumes) are now listed because they have filesystems installed on them.
Mount logical volumes
Now that our logical volumes are ready to be mounted. First let’s create out mountpoints:
$ mkdir /tmp/lvdata1 /tmp/lvdata2
Now we can either mount them manually, or automount them by adding the necessary entry in the /etc/fstab file.
In this demo we’ll manually mount the first LV and automount the second LV.
Let’s first do the manual mount:
$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk ├─sdb1 8:17 0 1.1G 0 part ├─sdb2 8:18 0 500M 0 part │ └─vgdata1vg-lvmyfirstlv 253:2 0 300M 0 lvm └─sdb3 8:19 0 503.6M 0 part └─vgdata1vg-lvmysecondlv 253:3 0 400M 0 lvm sr0 11:0 1 55.4M 0 rom $ mount /dev/vgdata1vg/lvmyfirstlv /tmp/lvdata1 $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk ├─sdb1 8:17 0 1.1G 0 part ├─sdb2 8:18 0 500M 0 part │ └─vgdata1vg-lvmyfirstlv 253:2 0 300M 0 lvm /tmp/lvdata1 # success └─sdb3 8:19 0 503.6M 0 part └─vgdata1vg-lvmysecondlv 253:3 0 400M 0 lvm sr0 11:0 1 55.4M 0 rom
Another check we can do is:
df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 18G 4.3G 14G 25% / devtmpfs 488M 0 488M 0% /dev tmpfs 497M 80K 497M 1% /dev/shm tmpfs 497M 7.0M 490M 2% /run tmpfs 497M 0 497M 0% /sys/fs/cgroup /dev/sda1 497M 143M 354M 29% /boot /dev/mapper/vgdata1vg-lvmyfirstlv 283M 2.1M 262M 1% /tmp/lvdata1
Now lets automate the mounting of the second LV by adding the entry in the /etc/fstab file:
$ cat /etc/fstab # # /etc/fstab # Created by anaconda on Sat Mar 14 19:14:11 2015 # # 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/centos-root / xfs defaults 1 1 UUID=547c78ce-34b5-4e31-84d2-bf72b196fa57 /boot xfs defaults 1 2 /dev/mapper/centos-swap swap swap defaults 0 0 /dev/mapper/vgdata1vg-lvmysecondlv /tmp/lvdata2 xfs defaults 0 0
Now let’s test our new entry by trying the automount:
$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk ├─sdb1 8:17 0 1.1G 0 part ├─sdb2 8:18 0 500M 0 part │ └─vgdata1vg-lvmyfirstlv 253:2 0 300M 0 lvm /tmp/lvdata1 └─sdb3 8:19 0 503.6M 0 part └─vgdata1vg-lvmysecondlv 253:3 0 400M 0 lvm sr0 11:0 1 55.4M 0 rom $ mount -a $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 19.5G 0 part ├─centos-swap 253:0 0 2G 0 lvm [SWAP] └─centos-root 253:1 0 17.5G 0 lvm / sdb 8:16 0 2.1G 0 disk ├─sdb1 8:17 0 1.1G 0 part ├─sdb2 8:18 0 500M 0 part │ └─vgdata1vg-lvmyfirstlv 253:2 0 300M 0 lvm /tmp/lvdata1 └─sdb3 8:19 0 503.6M 0 part └─vgdata1vg-lvmysecondlv 253:3 0 400M 0 lvm /tmp/lvdata2 sr0 11:0 1 55.4M 0 rom
We can confirm that this has worked using the mount, df, and the blkid commands:
$ df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 18G 4.3G 14G 25% / devtmpfs 488M 0 488M 0% /dev tmpfs 497M 80K 497M 1% /dev/shm tmpfs 497M 7.0M 490M 2% /run tmpfs 497M 0 497M 0% /sys/fs/cgroup /dev/sda1 497M 143M 354M 29% /boot /dev/mapper/vgdata1vg-lvmyfirstlv 283M 2.1M 262M 1% /tmp/lvdata1 /dev/mapper/vgdata1vg-lvmysecondlv 397M 21M 377M 6% /tmp/lvdata2 $ blkid | grep "vgdata1vg" /dev/mapper/vgdata1vg-lvmyfirstlv: UUID="c35e024a-fd04-45de-afc8-566c634593cd" TYPE="ext4" /dev/mapper/vgdata1vg-lvmysecondlv: UUID="02e140d7-0323-40d2-b7ee-5728f06305e3" TYPE="xfs" $ mount | grep "^/dev" /dev/mapper/centos-root on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota) /dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota) /dev/mapper/vgdata1vg-lvmyfirstlv on /tmp/lvdata1 type ext4 (rw,relatime,seclabel,data=ordered) /dev/mapper/vgdata1vg-lvmysecondlv on /tmp/lvdata2 type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
Now if we did go ahead and rebooted our machine then only our 2nd LV would get automounted since there is an entry for it in the /etc/fstab file.