Linux: Extend vg (Virtual Group) with new harddisk

January 15, 2014

Linux: Extend vg (Virtual Group) with new harddisk

Task: One of my volume /u01 is full. I need to expand the underlying volume /dev/mapper/vg_Sem01-lv_oracle. I want to add 50G. A new harddisk /dev/sdb is added and is ready for use.

Check if the new harddisk /dev/sdb is detected by the Linux

[root@SEM01 ~]# fdisk -l

Disk /dev/sda: 80.5 GB, 80530636800 bytes
255 heads, 63 sectors/track, 9790 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytesa
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0001e9c8

Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 9791 78130176 8e Linux LVM

Disk /dev/mapper/vg_Sem01-lv_root: 17.9 GB, 17909678080 bytes
255 heads, 63 sectors/track, 2177 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: 0x00000000

Disk /dev/mapper/vg_Sem01-lv_swap: 8405 MB, 8405385216 bytes
255 heads, 63 sectors/track, 1021 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: 0x00000000

Disk /dev/mapper/vg_Sem01-lv_oracle: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 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: 0x00000000

Disk /dev/sdb: 53.7 GB, 53687091200 bytes
64 heads, 32 sectors/track, 51200 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

List all the available physical volume

[root@SEM01 ~]# pvscan
PV /dev/sda2 VG vg_Sem01 lvm2 [74.51 GiB / 0 free]
Total: 1 [74.51 GiB] / in use: 1 [74.51 GiB] / in no VG: 0 [0 ]

only /dev/sda is available. It is because the new harddisk is not formatted.

Add /dev/sdb to the pv list

[root@SEM01 ~]# pvcreate /dev/sdb
Physical volume "/dev/sdb" successfully created

double check available pv again - pvscan

[root@SEM01 ~]# pvscan
PV /dev/sda2 VG vg_Sem01 lvm2 [74.51 GiB / 0 free]
PV /dev/sdb lvm2 [50.00 GiB]
Total: 2 [124.51 GiB] / in use: 1 [74.51 GiB] / in no VG: 1 [50.00 GiB]

We can see that now /dev/sdb is on the list.

Add /dev/sdb into the volume group: /dev/mapper/vg_Sem01-lv_oracle

Before start of the job, display the details of all physical volume first.
[root@SEM01 ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name vg_Sem01
PV Size 74.51 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 19074
Free PE 0
Allocated PE 19074
PV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX

"/dev/sdb" is a new physical volume of "50.00 GiB"

--- NEW Physical volume ---
PV Name /dev/sdb
VG Name
PV Size 50.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX

Find out how many vg is in the system

[root@SEM01 ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "vg_Sem01" using metadata type lvm2

[root@SEM01 ~]# vgdisplay
--- Volume group ---
VG Name vg_Sem01
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size 74.51 GiB
PE Size 4.00 MiB
Total PE 19074
Alloc PE / Size 19074 / 74.51 GiB
Free PE / Size 0 / 0
VG UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX

Add /dev/sdb into vg_Ssem01

[root@SEM01 ~]# vgextend vg_Sem01 /dev/sdb
Volume group "vg_Sem01" successfully extended

Use vgdisplay to check again. There are new Free PE.

[root@SEM01 ~]# vgdisplay
--- Volume group ---
VG Name vg_Sem01
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 5
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 2
Act PV 2
VG Size 124.50 GiB
PE Size 4.00 MiB
Total PE 31873
Alloc PE / Size 19074 / 74.51 GiB
Free PE / Size 12799 / 50.00 GiB
VG UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX

Use lvdisplay to display the current state of the logical volume

[root@SEM01 ~]# lvdisplay /dev/vg_Sem01/lv_oracle
--- Logical volume ---
LV Path /dev/vg_Sem01/lv_oracle
LV Name lv_oracle
VG Name vg_Sem01
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time SEM01.euicc.hksarg, 2013-09-06 10:31:09 +0800
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:2

Add 12799 new free PE to lv_oracle

[root@SEM01 ~]# lvextend -l +12799 /dev/vg_Sem01/lv_oracle
Extending logical volume lv_oracle to 100.00 GiB
Logical volume lv_oracle successfully resized
[root@SEM01 ~]#

The logical volume became 100GB now

[root@SEM01 ~]# lvdisplay /dev/vg_Sem01/lv_oracle
--- Logical volume ---
LV Path /dev/vg_Sem01/lv_oracle
LV Name lv_oracle
VG Name vg_Sem01
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time SEM01.euicc.hksarg, 2013-09-06 10:31:09 +0800
LV Status available
# open 1
LV Size 100.00 GiB
Current LE 25599
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:2

The file system will not resize automatically with the lv (Logical Volume). The new space is not usable at this moment.

Online resize the file system

[root@SEM01 ~]# resize2fs /dev/vg_Sem01/lv_oracle
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_Sem01/lv_oracle is mounted on /u01; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 7
Performing an on-line resize of /dev/vg_Sem01/lv_oracle to 26213376 (4k) blocks.
The filesystem on /dev/vg_Sem01/lv_oracle is now 26213376 blocks long.

check disk free now

[root@SEM01 ~]# df /u01
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_Sem01-lv_oracle
103208224 40331152 57635036 42% /u01

Now /u01 can use the new free space and the space utilization is dropped to a reasonable level.

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