For increasing (or reducing) the size of the file system, we can use its flexible advantage to mange disk resource if the system deploys LVM.
At first, we have to realize whether can use all available space on the Logical Volume.
If have, we can directly grow the file system from the free space of Volume Group.
If no, we have to expand the Volume Group by adding the additional disk.
In the following lab, it will show you how to grow file system after add new disk because its operation also includes directly expand the space on LV.
PrerequisiteTo check the size of the file system to realize whether the space then needs to be extend by using
df –h command
In the moment, the available space is 41MB and all space use 96% on the filesystem
/dev/mapper/drbdVG00-drbdLV0By using
lvdisplay /dev/mapper/drbdVG00-drbdLV0 command, we can find out which Volume Group Name
drbdVG00 contain this Logical Volume.
By using
vgdisplay drbdVG00 command, we can find out whether the volume group
drbdVG00 has available free space
to allocate to the logical volume.
In the moment, there is no free physical extents so that need to add new disk as adding physical volume to this volume group.
After add new disk online (# 1), we need to confirm whether the system can probe this new disk by using
ls /dev/sd* command
or realize what is the status of the partition of the disk by using
df –h command
Create Physical VolumeDue to the new disk never is partitioned, we will create the whole disk as a physical volume so that will convert this disk into a physical volume by using
pvcreate /dev/sdc command.
By using
pvscan or
pvscan –n command, we can know whether the physical volume is created successfully and are sure this new physical volume never belongs to any volume group now.
Add Physical Volume into the existing Volume GroupAfter the physical volume is created, we need to add it to the existing volume group by using
vgextend drbdVG00 /dev/sdc command.
In volume group, there is free physical content that is ready to be allocated to logical volume now by using
vgdisplay drbdVG00 command.
Extend Logical Volume SizeBy using
lvextend –L +1020M /dev/drbdVG00/drbdLV0 command, we will extend the size of Logical Volume about 1020 MB.
The “AS-IS” of using
lvextend command
The “TO-BE” of using
lvextend command
Resize FilesystemBy using
resize2fs /dev/drbdVG00/drbdLV0 command, we can resize filesystem so that logical volume will have additional space to be used now.
Until now, we can use the additional space that provided by the new disk if the above process completes successfully.
Reference :
(# 1) In Hyper-V 3.0 manager, we can add the SCSI virtual disk online
and choose a location value to avoid the conflict with the existing disk.
This is why I want to add a GUI to CentOS at the moment.
To start X Windows by typing startx command
The X Windows will show up
and we can initialize the Logical Volume Management now.
According to database path rule, by default all database files are located under the default location as /var/lib/mysql/"db_name", we can use find / –name “db_name” –print command to find out the special database path. 
Finally, if we want to know the default data directory on MySQL now,we can use sql command as SHOW VARIABLES LIKE ‘datadir’;
or mysqladmin command as mysqladmin –u root –p variables | grep datadir
If it non-exists we have to create network interface.
To create a file by using vi /etc/sysconfig/network-scripts/ifcfg-eth0 command and add some word as follows:
for getting dynamic IP
for setting static IP (# 1)
End if
In general, we just need to delete the first row and change NAME’s value from eth1 to eth0 at the second row
The final result is as follows:
After log on the system, the network function will be normal now.
To verify the status of the new physical volume by using pvdisplay /dev/sdd command
To realize which volume group the bad or old disk ( /dev/sdb1) belongs to by using pvdisplay /dev/sdb1 command
To add the new disk ( /dev/sdd) to the volume group drbdVG00 by using vgextend drbdVG00 /dev/sdd command
To realize which logical volume the volume group drbdVG00 belong to by using lvdisplay command
To move physical extents in active volume group drbdVG00 from /dev/sdb1 to /dev/sdd by using pvmove –n drbdVG00 /dev/sdb1 /dev/sdd command
To remove bad or old disk from the volume group by using vgreduce drbdVG00 /dev/sdb1 command
Finally, please shutdown the system next to remove the bad or old disk (# 1) and boot it. The data still exist in LVM disk as before.
all disk order will be changed but LVM function is normal.
the bad or old disk just is replaced with the new disk and LVM function is normal as well.
In the moment, the available space is 41MB and all space use 96% on the filesystem /dev/mapper/drbdVG00-drbdLV0
In the moment, there is no free physical extents so that need to add new disk as adding physical volume to this volume group.
or realize what is the status of the partition of the disk by using df –h command
By using pvscan or pvscan –n command, we can know whether the physical volume is created successfully and are sure this new physical volume never belongs to any volume group now.
In volume group, there is free physical content that is ready to be allocated to logical volume now by using vgdisplay drbdVG00 command.
Extend Logical Volume SizeBy using lvextend –L +1020M /dev/drbdVG00/drbdLV0 command, we will extend the size of Logical Volume about 1020 MB.
The “AS-IS” of using lvextend command
The “TO-BE” of using lvextend command
Until now, we can use the additional space that provided by the new disk if the above process completes successfully.
