OSVDC: Virtual Disk Management on oVirt 4 and CentOS 7

Scenario

A virtual machine from a template utilizes one virtual disk. The application administrator has requested an increased capacity from 20 GB to 50 GB. The Linux administrator has chosen to increase capacity of the existing virtual disk versus creating and growing or mounting a second virtual disk.

Current State

Use pvdisplay, vgdisplay, and lvdisplay to review current storage configuration.

[root@sw ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/vda2
  VG Name               centos
  PV Size               19.51 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               10
  Allocated PE          4984
  PV UUID               E34TI0-jnr3-8vIF-4rET-GILo-haID-VzmLkC

[root@sw ~]# vgdisplay
  --- Volume group ---
  VG Name               centos
  System ID
  Format                lvm2
  Metadata Areas        1
  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                1
  Act PV                1
  VG Size               19.51 GiB
  PE Size               4.00 MiB
  Total PE              4994
  Alloc PE / Size       4984 / 19.47 GiB
  Free  PE / Size       10 / 40.00 MiB
  VG UUID               AXJ9w1-jQXX-02Rk-SrFV-eqcD-oirw-xIfHhY

[root@sw ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                5pOoUm-LMP6-5xTo-tNEL-Eil5-QG1t-gq7u3S
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2016-11-10 20:44:13 -0800
  LV Status              available
  # open                 2
  LV Size                2.00 GiB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1

  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                pyHQFR-KUHQ-pC1R-JR06-yRpA-AzcJ-Yl9Tu5
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2016-11-10 20:44:13 -0800
  LV Status              available
  # open                 1
  LV Size                17.47 GiB
  Current LE             4472
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

Extend Disk

Using the oVirt administrator portal, extend the virtual disk.

Authenticate to oVirt (Open Virtualization Manager)
Shutdown VM (optional?)
Select "Virtual Machines" tab
Select the VM to edit in main pane
Select "Disks" tab in bottom pane
Select "Edit" menu
Enter "Extend size by(GB)" value
Select "OK"
Poweron VM

Repartition Disk

Using fdisk recreate and increase capacity of the desired primary partition.

Logon to VM
Execute "fdisk /dev/vda"
Enter "p" and note the "Linux LVM" device vda2
Enter "d" and delete vda2
Enter "n" and create 'primary' and accept the default sectors
Enter "t" and specify "8e" to set the new partition as 'Linux VM'
Enter "w" to save changes
"reboot"

Results

[root@sw ~]# fdisk /dev/vda
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): p

Disk /dev/vda: 53.7 GB, 53687091200 bytes, 104857600 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: 0x00088d6e

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     1026047      512000   83  Linux
/dev/vda2         1026048    41943039    20458496   8e  Linux LVM

Command (m for help): d
Partition number (1,2, default 2):
Partition 2 is deleted

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 (1026048-104857599, default 1026048):
Using default value 1026048
Last sector, +sectors or +size{K,M,G} (1026048-104857599, default 104857599):
Using default value 104857599
Partition 2 of type Linux and of size 49.5 GiB is set

Command (m for help): t
Partition number (1,2, default 2):
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p

Disk /dev/vda: 53.7 GB, 53687091200 bytes, 104857600 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: 0x00088d6e

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     1026047      512000   83  Linux
/dev/vda2         1026048   104857599    51915776   8e  Linux LVM

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[root@sw ~]# reboot

Resize Physical Volume

Use pvresize to utilize the additional storage.

Logon to the virtual machine
Execute "pvresize /dev/vda2"

Results

[root@sw ~]# pvresize /dev/vda2
  Physical volume "/dev/vda2" changed
  1 physical volume(s) resized / 0 physical volume(s) not resized
[root@sw ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/vda2
  VG Name               centos
  PV Size               49.51 GiB / not usable 2.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              12674
  Free PE               7690
  Allocated PE          4984
  PV UUID               E34TI0-jnr3-8vIF-4rET-GILo-haID-VzmLkC

[root@sw ~]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree
  centos   1   2   0 wz--n- 49.51g 30.04g

Resize Logical Volume

Use lvextend extend the logical volume extents and file system.

Execute "vgs" and note "VFree" or available space
Execute "lvextend --resizefs --extents +100%FREE /dev/centos/root"
Review the results using "vgs"
Execute "reboot"

Results

[root@sw ~]# lvextend --resizefs --extents +100%FREE /dev/centos/root
  Size of logical volume centos/root changed from 17.47 GiB (4472 extents) to 47.51 GiB (12162 extents).
  Logical volume centos/root successfully resized.
meta-data=/dev/mapper/centos-root isize=256    agcount=4, agsize=1144832 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=0        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=4579328, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=0
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 4579328 to 12453888
[root@sw ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                5pOoUm-LMP6-5xTo-tNEL-Eil5-QG1t-gq7u3S
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2016-11-10 20:44:13 -0800
  LV Status              available
  # open                 2
  LV Size                2.00 GiB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1

  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                pyHQFR-KUHQ-pC1R-JR06-yRpA-AzcJ-Yl9Tu5
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2016-11-10 20:44:13 -0800
  LV Status              available
  # open                 1
  LV Size                47.51 GiB
  Current LE             12162
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

Also,

[root@sw ~]# df -h /
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   48G  1.3G   47G   3% /

Shutdown and backup or snap the virtual host.

Common storage commands:

fdisk
lsblk
pvdisplay
vgdisplay
lvdisplay
vgs
df
du; du -x <dirname> | sort -nr |more

OSVDC Series: Virtual Disk Management on oVirt 4 and CentOS 7 - rharmonson/richtech GitHub Wiki

OSVDC: Virtual Disk Management on oVirt 4 and CentOS 7

Current State

Extend Disk

Repartition Disk

Resize Physical Volume

Resize Logical Volume

Common storage commands:

⚠️ GitHub.com Fallback ⚠️

OSVDC Series: Virtual Disk Management on oVirt 4 and CentOS 7 - rharmonson/richtech GitHub Wiki

OSVDC: Virtual Disk Management on oVirt 4 and CentOS 7

Current State

Extend Disk

Repartition Disk

Resize Physical Volume

Resize Logical Volume

Common storage commands:

⚠️ **GitHub.com Fallback** ⚠️

⚠️ GitHub.com Fallback ⚠️