Extending XFS Partition Based LVM by Increasing the Disk Size

This is the original disk layout before the disk extension

We can see that the LVM is built on /dev/sda2, which is a partition, and not a disk. The disk, /dev/sda is now extended by 100G on the VM manager level. After a reboot, we can now see that the disk size is now 130G. 

 

To include this new space into existing LVM, create a new partition on the new disk space using a tool called cfdisk. Please refer to this post on how to use cfdisk to create a new partition.

The first step is to become root. If you prefer using sudo, please append sudo on each of these commands.

Once we can see that the partition is available, create a new physical volume (PV) using the new partition. 

# pvcreate /dev/sda3 

We should see the message as per below

Then, check what is the name of our volume group (VG)

# vgs 

Extend our VG by including the new PV

# vgextend centos /dev/sda3 

Check what is our logical volume (LV) path

# lvdisplay | grep Path 

Extend our LV to use the whole free space available on the VG

# lvextend -l +100%FREE /dev/centos/root

Check that our LV's size is now expanded 

# lvs 

Determine what is our filesystem type, at the same time we can see that our filesystem is not aware of the new size 

# df -Th / 

Grow xfs filesystem to suit the new partition size

# xfs_growfs /  

We can see that the filesystem is now grown to the full size as per our LV

# df -Th / 

 

Extending LVM By Adding New Disk To a Virtual Machine

In previous post, we have covered the way to make LVM and filesystem aware of the disk size increase that happen in the virtual machine layer. 

There is another way to increase LVM volume capacity, that is to add new disk into the system. 

1. First, shutdown the virtual machine

2. Add a new virtual disk size into the virtual machine manager

3. Start the virtual machine

4. Check the new disk availability for LVM

$ sudo lvmdiskscan

5. To be able to use the new disk, it needs to be converted into physical volume (PV)

$ sudo pvcreate <path to the new disk>

6. Check list of PVs. Memorize the PV name

$ sudo pvs

7. Extend the volume group using the new PV

$ sudo vgextend <VG name> <PV name>

We can get the name of the VG by using this command. This command also will show how much free space is now available in the VG.

$ sudo vgs

8. Increase the size of logical volume, to use 100% of the free space available inside VG, using this command

$ sudo lvextend -l +100%FREE <LV PATH>

We can get the full  path of LV using this command

$ sudo lvdisplay | grep Path

9. Now, make the filesystem aware that the partition size has been increased. The command to do this differ from filesystem to filesystem, but we include 2 of the most used (based on our experience) filesystem

For xfs:

$ sudo xfs_growfs <mountpoint>

For  ext4:

$ sudo resize2fs <mountpoint>

10. Verify that the mountpoint is now increase in size

$ df -Th

Extending Virtual Disk in a Linux Virtual Machine Using LVM

To increase a disk size in a virtual machine with Linux operating system configured with LVM, below are the steps (these steps were tested using virtualbox):

1. Power off the virtual machine

2. Increase the virtual disk size in the virtual machine using the virtual machine manager

3. Restart the virtual machine

4. Even though the virtual disk has been increased in size, but LVM is not aware of the change. To make LVM aware of the change, run pvresize command

$ sudo pvresize <pv name>

You can get the physical volume (PV) name by running "pvs" command

$ sudo pvs

5. Once the physical volume (PV) has been resized, run "vgs" to see the new volume group (VG) size

$ sudo vgs

6. Resize logical volume (LV) to make the new size available for us to use. Use below command to resize LV to use 100% of the free space available in VG

$ sudo lvextend -l +100%FREE <LV path>

You can get the LV path by running lvdisplay

$ sudo lvdisplay | grep Path

7. Now the partition is aware of the size change, but not the filesystem. Check the filesystem type and mountpoint using below command

$ df -Th

8. Depending on the filesystem type, extend your filesystem to suit the new partition size. 

For xfs:

$ sudo xfs_growfs <mountpoint>

and for ext4:

$ sudo resize2fs <mountpoint>

9. Verify that your filesystem is now using the new size

$ df -Th

Extending / in Default CentOS Partitioning Scheme

The default partitioning scheme for CentOS is not ideal, because the installer only give 50Gb to /. and the rest to /home. Luckily, the partitions are being setup in LVM, thus enable us to change it without reinstalling the operating system. 

In this example, I will show how to remove logical volume used by /home, and assign it to / instead.

First of all, you need to be root in order to do this.

This is the original partition layout:

# df -Th

Filesystem          Type      Size  Used Avail Use% Mounted on

...

/dev/mapper/cl-root xfs        50G  4.1G   46G   9% /

/dev/mapper/cl-home xfs       1.9T   14G  1.9T   1% /home

/dev/vda1           ext4      976M  194M  716M  22% /boot

...

As you can see, we are not going to use 1.9T in /home, so we are going to assign that to / instead.

Second step, make a backup of /home

# cp -apv /home /home2

Next, unmount /home

# umount -fl /home

Remove the logical volume

# lvremove /dev/cl/home

If you get an error saying that the logical volume is in used, you need to kill off the process first.

Get the major, minor number of the logical volume.

# dmsetup -c info cl-home

Name             Maj Min Stat Open Targ Event  UUID                                                                

cl-home          253   2 L--w    1    1      0 LVM-urbQSwHWhdpFDeVDQA3yFkOjVMkWFGloYGbgzAGW8YOuwacqVZLvVx23qNVJTFHc

Search for the process and process id using the major,minor number

# lsof | grep "253,2"

java       179094                           user  cwd       DIR              253,2        95 1073741952 /home

...

kill off the process

# kill 179094

Try to remove the logical volume again

# lvremove /dev/cl/home

Once deleted, extend the logical volume of /dev/cl/root, to use 100% of free space available in the volume group

# lvextend -l +100%FREE cl-root

Check the filesystem type

# df -Th /

Filesystem          Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root xfs        50G  4.6G   46G  10% /

Extend the filesystem, xfs_growfs is xfs filesystem grow tool. For ext4, you need to use resize2fs command

# xfs_growfs /

Check that your / partition is showing the new size

# df -Th /

Filesystem          Type  Size  Used Avail Use% Mounted on

/dev/mapper/cl-root xfs   2.0T   19G  2.0T   1% /

Copy back the content of /home2 to /home

# mv /home2/* /home

IMPORTANT: Remove the old /home mount entry in /etc/fstab

# sed -i.ori '/home/d' /etc/fstab

The last step is very important, it can cause your operating system to fail to boot if /etc/fstab is not configured properly.

Enjoy your newly gained disk space in / partition.

Rename and Remount LVM Logical Volume

A usual scenario where rename and remount of LVM logical volume are needed, is when you install a box with a CentOS, and use the default LVM based partitioning scheme. This scheme will take 50G for your / partition, and the rest will be allocated to your /home, which is not practical. In this example, we will be remounting logical volume originally mounted to /home, to /var/lib/elasticsearch, renaming it along the way.

The original partition scheme 

# df -Th

Filesystem                   Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root          xfs        50G  3.0G   48G   6% /

/dev/sda1                    xfs      1014M  179M  836M  18% /boot

/dev/mapper/cl-home xfs       965G   42G  924G   5% /home

Stop the service that might be using the partition that we are going to change

# systemctl stop elasticsearch

Rename the original directory to other name

# mv /var/lib/elasticsearch /var/lib/elasticsearch-old

Create a new directory to replace the one we already renamed above

# mkdir /var/lib/elasticsearch

Unmount /home

# umount /home

Check the name of volume group and logical volume

# lvs

Rename the logical volume to the one we desired. This is totally optional. You can use -t flag to test out the renaming process before proceeding

# lvrename -t cl home elasticsearch

# lvrename cl home elasticsearch

Change /etc/fstab to reflect on the new logical volume name and mount point. Test it out without the  -i option, before permanently make the change using the -i option

# sed 's/cl-home/cl-elasticsearch/g;s/\/home/\/var\/lib\/elasticsearch/g' /etc/fstab

# sed -i 's/cl-home/cl-elasticsearch/g;s/\/home/\/var\/lib\/elasticsearch/g' /etc/fstab

Mount it

# mount -a

Check to see if your new directory and logical volume mounted properly

# df -Th

Filesystem                   Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root          xfs        50G  3.0G   48G   6% /

/dev/sda1                    xfs      1014M  179M  836M  18% /boot

/dev/mapper/cl-elasticsearch xfs       965G   42G  924G   5% /var/lib/elasticsearch

Move the content of /var/lib/elasticsearch to /home

# mv /var/lib/elasticsearch/* /home

Move the content of /var/lib/elasticsearch-old to /var/lib/elasticsearch

# mv /var/lib/elasticsearch-old/* /var/lib/elasticsearch

Remove /var/lib/elasticsearch-old

# rmdir /var/lib/elasticsearch-old

Set proper permission for /var/lib/elasticsearch

# chmod 750 -R /var/lib/elasticsearch

# chown -R elasticsearch.elasticsearch /var/lib/elasticsearch

Start your service

# systemctl start elasticsearch

Done.

Resizing partition in centos after vmware hardisk extension

This is usually done, when the hardisk space for the CentOS VM is running low.

Check your current disk size

# fdisk -lu /dev/sda

To increase the size of the hardisk image, shutdown the centos VM

# poweroff

Increase the hardisk image in VMware

Power on the centos VM

Once logged in, check back whether you have increased your disk size

# fdisk -lu /dev/sda

Create new partition on the new disk space

# fdisk /dev/sda

Press:

n   {new partition}

p   {primary partition}

3   {partition number}

t    {change partition id}

8e {Linux LVM partition}

w  {write partition change to disk}

Reboot the vm

# reboot

Check the new partition

# fdisk -lu /dev/sda

Create physical volume (PV) on the new partition

# pvcreate /dev/sda3

Check list of PV

# pvs

Extend the current Volume Group (VG) to include the new PV, and check the new VG size

# vgextend centos /dev/sda3

# vgs

Extend the current Logical Volume (LV), and check the new size of logical volume 

# lvextend /dev/mapper/centos-root /dev/sda3

# lvs

Resize / partition

# resize2fs /dev/mapper/centos-root

Check the new size

# df -h /

before resize:

after resize:

Extending LVM logical volume

To extend the lv (logical volume), the command is lvextend. Please check beforehand that you have free disk space to be extended to.

Check which volume group the partition belongs to:

# df -lh
Filesystem            Size  Used Avail Use% Mounted on
...
/dev/mapper/vg01-db   6.0T  6.0T   20K 100% /var/lib/hwbackup/db
...

# lvdisplay vg01
--- Logical volume ---
  LV Name                /dev/vg01/db
  VG Name                vg01
  LV UUID                2LvWW6-5TIG-ovrl-GUJt-1y3N-M6ME-3LgtUY
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                5.99 TB
  Current LE             1569792
  Segments               5
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     4096
  Block device           253:2

So, our lv belongs to vg01

Now let's check how much space we have for vg01:

# vgdisplay vg01
...
  Alloc PE / Size       4059648 / 15.49 TB
  Free  PE / Size       232788 / 909.33 GB
  VG UUID               iaFnIb-hKjs-q3fQ-yuTy-tKKl-uqSp-EXGyHF
...

So we know that it got 909.33 GB unused space.

Lets do the extension, let's say we want to extend by 300GB. Run a test run first:

# lvextend -t -v -L +300G /dev/mapper/vg01-db
Test mode: Metadata will NOT be updated.
    Finding volume group vg01
  Using stripesize of last segment 512.00 KB
    Test mode: Skipping archiving of volume group.
  Extending logical volume db to 6.28 TB
    Found volume group "vg01"
    Found volume group "vg01"
    Found volume group "vg01"
    Test mode: Skipping volume group backup.
  Logical volume db successfully resized
    Test mode: Wiping internal cache
    Wiping internal VG cache
[root@hitw-gc-backup-1 ~]# lvextend -v -L +300G /dev/mapper/vg01-db
    Finding volume group vg01
  Using stripesize of last segment 512.00 KB
    Archiving volume group "vg01" metadata (seqno 19).
  Extending logical volume db to 6.28 TB
    Found volume group "vg01"
    Found volume group "vg01"
    Loading vg01-db table (253:2)
    Suspending vg01-db (253:2) with device flush
    Found volume group "vg01"
    Resuming vg01-db (253:2)
    Creating volume group backup "/etc/lvm/backup/vg01" (seqno 20).
  Logical volume db successfully resized

where -t is for test mode, -v for verbose and -L is for the size that you want to extend

If we are OK with the test, proceed to the real extension by removing -t:

# lvextend -v -L +300G /dev/mapper/vg01-db
    Finding volume group vg01
  Using stripesize of last segment 512.00 KB
    Archiving volume group "vg01" metadata (seqno 19).
  Extending logical volume db to 6.28 TB
    Found volume group "vg01"
    Found volume group "vg01"
    Loading vg01-db table (253:2)
    Suspending vg01-db (253:2) with device flush
    Found volume group "vg01"
    Resuming vg01-db (253:2)
    Creating volume group backup "/etc/lvm/backup/vg01" (seqno 20).
  Logical volume db successfully resized

Check your new lv size, it is now being extended by 300GB:

# lvdisplay /dev/mapper/vg01-db
...
 LV Size                6.28 TB
...

To make your filesystem aware of the extension, run resize2fs (for ext3 filesystem). Please unmount the partition beofre you run resize2fs

# umount /dev/mapper/vg01-db

# resize2fs /dev/mapper/vg01-db

# mount /dev/mapper/vg01-db /var/lib/hwbackup/db

For xfs, you can resize it on the fly without unmounting it:

# xfs_growfs /var/lib/hwbackup/db

Now you can enjoy your newly extended lv:

# df -lh
Filesystem            Size  Used Avail Use% Mounted on
...
/dev/mapper/vg01-db   6.3T  5.7T  608G  91% /var/lib/hwbackup/db
...

Accessing data on xen lvm guest image

Accessing xen guest image is very easy if the image is not lvm partitioned. But the main problem arise when the image is of lvm format and normal mount command cannot be used. Here I will show both the way. The first is when ext filesystem is used, and the second is when lvm is used.

To mount xen guest image (without lvm)

1. check the partition on the image
# fdisk -lu
The result will be something like this:



2. Mount using offset option
# mount -o loop,offset=106929152 /path/to/image /mnt
where 106929152=208846*512, 208846 is the start of the partition. Using this way, you only mount the second partition and not the whole image

3. You can now access your image at /mnt

To mount xen guest image (with lvm)

1. Check the partition on the image
# fdisk -lu /path/to/image

2. You have to install kpartx to handle lvm partiton
# yum install kpartx

3. Run kpartx on the image
# kpartx -av /path/to/image

4. Run vgscan to scan volume group available
# vgscan

5. Run vgchange to activate the volume group in the image
# vgchange -ay VolGroup00

6. Use lvs to see what is the name of your low volume group
# lvs

7. Mount the low volume group
# mount /dev/VolGroup00/LogVol01 /mnt

8. You can access your lvm image at the mounted directory which is /mnt

9. To unmount it, a few commands have to be executed (umount for unmounting, vgchange -an to deactivate volume group, kpartx -d to delete device map and losetup -d to delete loop device used)
# umount /mnt/
# vgchange -an VolGroup00
# kpartx -d /path/to/image
# losetup -d /dev/loop0

Hope this will be useful

Mounting LVM Disk using Ubuntu livecd

Mounting is an easy process to do, provided the filesystem type you are using is supported. What happen when you have an LVM formatted disk, and you need to mount it because the disk cannot be booted and a hell lot of valuable data kept inside?? Do not worry, because the solution is here.......

1. Get a live cd, for example, Ubuntu. For this article, I use Ubuntu 6.06 (I cannot find any latest version of ubuntu at my place)

2. Boot using the live cd. Search for these tools: lvm2. If the cd do not have it, install it.
# apt-get install lvm2

3. To make sure the harddisk is recognised, you can use fdisk
# fdisk -lu

4. Once installed, run pvscan to scan all disks for physical volume. this to make sure your LVM harddisk is detected by Ubuntu
# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [74.41 GB / 32.00 MB free]
Total: 1 [74.41 GB] / in use: 1 [74.41 GB] / in no VG: 0 [0 ]


5. After that run vgscan to scan disks for volume groups.
# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VolGroup00" using metadata type lvm2


6. Activate all volume groups available.
# vgchange -a y
2 logical volume(s) in volume group "VolGroup00" now active

7. Run lvscan to scan all disks for logical volume. You can see partitions inside the hard disk now active.
# lvscan
ACTIVE '/dev/VolGroup00/LogVol00' [72.44 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol01' [1.94 GB] inherit

8. Mount the partition to any directory you want, usually to /mnt
# mount /dev/VolGroup00/LogVol00 /mnt

9. You can access the partition in the /mnt directory and can backup your data