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How to configure LVM in Linux server.
LVM or Logical Volume Management is a tool used by Unix/Linux administrators to manage disk resources. LVM provides a layer of abstraction between the underlying physical disk/volume and the host operating system. LVM partitions can span across physical hard drives and can be re-sized.
We can use the following steps to create LVM.
Partitioning
Physical volume(s) creation
Volume group(s) creation
Logical volume(s) creation
Formatting of the file system
Mounting of file system
Updating fstab for automatic volume mounting
Create Partition
Use this LVM configuration in Linux cpanel server, LVM partitions must be of type 8e (Linux LVM.) Create new partition and make sure with ID 8e.
[root@localhost ~]# fdisk -l
Disk /dev/sda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000d5460
Device Boot Start End Blocks Id System
/dev/sda1 1 1306 10484736 8e Linux LVM
if not then you can create partition with the type of the file system to 8e using t option.
[root@localhost ~]# fdisk /dev/sda
Physical Volume (PV)
physical storage unit of an LVM logical volume is a block device such as a partition or whole disk. To use the device for an LVM logical volume the device must be initialized as a physical volume (PV).
Check whether any physical volumes (PV’s) already exist on the system.
[root@localhost ~]# pvdisplay
Use the following command to create Physical Volume
[root@localhost ~]#pvcreate /dev/sda1
Physical volume “/dev/sda1” successfully created
[root@localhost ~]#
Volume Group (VG)
Physical volumes are combined into volume groups (VGs). This creates a pool of disk space out of which logical volumes can be allocated. Within a volume group, the disk space available for allocation is divided into units of a fixed-size called extents.
Check Volume Groups the are already present on the system
[root@localhost ~]# vgdisplay
Create Volume Group
[root@localhost ~]# vgcreate VolGroup /dev/sda1
Volume group “VolGroup” successfully created
[root@localhost ~]# vgdisplay
— Volume group —
VG Name VolGroup
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
VG Size 10.70 GiB
PE Size 4.00 MiB
Total PE 4481
Alloc PE / Size 4481 / 10.70 GiB
Free PE / Size 0 / 0
VG UUID TGFbtz-ysqf-XE8e-fDb0-dRzh-hfzE-Jx484g
Logical Volume
we have a Volume Group created that has free physical extents, we are now ready to create our new Logical Volume (LV). LV’s can be created using a number of extents (with the -l command line switch) or by total size (with the -L command line switch followed by KB, MB, GB or TB.)
just use this command to create LV with all the space from that VG.
lvcreate
[root@localhost ~]#lvcreate lv_home VolGroup
Logical volume “lv_home” created
[root@localhost ~]# lvdisplay
— Logical volume —
LV Name /dev/VolGroup/lv_home
VG Name VolGroup
LV UUID trHeKm-Cxbu-cApC-IaHd-gxRW-RMdC-dw4msV
LV Write Access read/write
LV Status available
# open 1
LV Size 10.54 GiB
Current LE 4233
Segments 2
Allocation inherit
Read ahead sectors auto
– currently set to 256
Block device 253:0
If you need 4G of LV then define a new LV that is 4GB in size
[root@localhost ~]#lvcreate -L 4GB -n lv_home VolGroup
Logical volume “lv_home” created
To create LV with full disk space
[root@localhost ~]# lvcreate -n lv_home -l 100%FREE VolGroup
Logical volume “lv-home” created
Formatting a File System
Linux offers many different file systems, some distributions of Linux/Unix will tend to recommend EXT3 while others might recommend XFS or ReiserFS.
[root@localhost ~]#mke2fs -j /dev/VolGroup/lv_home
Mounting a File System
create and mount that drive for your directory.
[root@localhost ~]#mkdir /home
[root@localhost ~]#mount /dev/VolGroup/lv_home /home
Once completed view your mounted device.
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_home
10G 789M 8G 7% /home
Thats all!!!
To remove LV, you can use this command.
[root@gopal ~]# lvremove /dev/VolGroup/lv_home
Do you really want to remove active logical volume lv_home? [y/n]: y
Logical volume “lv_home” successfully removed
Using LVextend Command
Change the size of the logical volumes Using lvextend Command
We can extend the size of the logical volumes after creating it by using lvextend utility.
For example logical volume extend size of 100M
[root@gopal ~]# umount /dev/VolGroup/lv_home
Volume group free space will add to LV.
[root@gopal ~]#lvextend -L+100 /dev/VolGroup/lv_home
Extending logical volume lv_home to 100.00 MB
Logical volume lv_home successfully resized
[root@gopal ~]# e2fsck -f /dev/VolGroup/lv_home
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/VolGroup/lv_home: 12/131072 files (0.0% non-contiguous), 25388/524288 blocks
[root@gopal ~]# resize2fs /dev/VolGroup/lv_home
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/home2lvm-lv_home2 to 786432 (4k) blocks.
The filesystem on /dev/mapper/home2lvm-lv_home2 is now 786432 blocks long.
Mount that partition now.
[root@gopal ~]# mount /dev/VolGroup/lv_home /home2
/dev/mapper/home2lvm-lv_home2
3.0G 67M 2.8G 3% /home2
That’s All….
How to increase mounted partition size in LVM
Its is possible to grow a partition safely without unmounting and remounting your volume. These steps presume you have extra disk available on your volume which is currently unallocated.
Run pvscan to verify you have allocatable space in your target Logical Volume:
pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [19.88 GB / 1020.00 MB free]
PV /dev/sdb VG VolGroup01 lvm2 [100.00 GB / 20.00 GB free]
From the output, you can see VolGroup01, which contains the partition want to grow, had some free space.
Run lvresize to add free space to your partition:
VG name : home2lvm
LVname : lv_home2
[root@gopal ~]# lvresize -L+1.9G -n /dev/mapper/home2lvm-lv_home2
Rounding size to boundary between physical extents: 1.90 GiB
Extending logical volume lv_home2 to 4.90 GiB
Logical volume lv_home2 successfully resized
[root@gopal ~]# resize2fs /dev/home2lvm/lv_home2
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/home2lvm/lv_home2 is mounted on /home2; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/home2lvm/lv_home2 to 1285120 (4k) blocks.
The filesystem on /dev/home2lvm/lv_home2 is now 1285120 blocks long.
Verify the disk space added in your current volume.
df -h
How to use VGExtend ?
When you add new drive, you can extend Volume Group and resize LV with out unmount.
After new drive attached, create partition with LVM code 8e.
Create PV
[root@gopal ~]# pvcreate /dev/xvdc1
Physical volume “/dev/xvdc1” successfully created
[root@gopal ~]# vgextend home2lvm /dev/xvdc1
Volume group “home2lvm” successfully extended
VGExtend
[root@gopal ~]# vgextend home2lvm /dev/xvdc1
Volume group “home2lvm” successfully extended
LVresize
[root@gopal ~]# lvresize -L+2.05G -n /dev/mapper/home2lvm-lv_home2
Rounding size to boundary between physical extents: 2.05 GiB
Extending logical volume lv_home2 to 6.95 GiB
Logical volume lv_home2 successfully resized
[root@gopal ~]# resize2fs /dev/mapper/home2lvm-lv_home2
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/home2lvm-lv_home2 is mounted on /home2; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mapper/home2lvm-lv_home2 to 1822720 (4k) blocks.
The filesystem on /dev/mapper/home2lvm-lv_home2 is now 1822720 blocks long.
You are Done!!! Check with drive size
df -h
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