| |
First, the traditional disk management problems
When the partition size is not enough when you can not expand its size by adding only disk, create a new partition to expand space, but add in the new hard disk as a separate file system exists, the original file system has not been expanded, the upper application Very often only have access to a file system. Only make existing disk offline, then replaced with a new disk, and then import the raw data.
Second, the basic concepts of LVM logical volumes
LVM (Logical volume Manager) Logical Volume Manager by abstraction of the underlying physical hard disk encapsulated in the form of logical expression to the upper system, the logical volume size can be dynamically adjusted, and will not lose any existing data. Newly added hard disk does not change the existing upper logical volume.
As a dynamic disk management mechanism, technology has greatly enhanced the flexibility of logical disk management.
PE (physical extend) defaults to 4MB of basic blocks
PV (physical volume) hard disk or partition
Overall VG (volume group) consisting of one or more of PV
LV (logical volume) cut out from VG in space to create a file system
Three, LVM creation process
1. The physical disk is formatted as a PV, a space is divided into a PE
2. nowhere PV join the same VG, different PV of all entered the VG PE PE tanks
3.LV created based on PE, PE is an integer multiple of the size, the LV PE composition may come from different physical disks
After 4.LV format can now directly use the mount
5.LV expansion reduction is actually to increase or decrease the number of PE in the composition of the LV. The process without losing the original data
Fourth, create LVM
The physical disk device is initialized as a physical volume
pvcreate / dev / sdb / dev / sdc
Create a volume group and the volume group PV added
vgcreate vg0 / dev / sdb / dev / sdc
Create a logical volume-based group
lvcreate -n lv0 -L 5G vg0
Create a logical file system to create good
mkfs.ext4 / dev / vg0 / lv0
The formatted logical volumes mount use
mount / dev / vg0 / lv0 / mnt /
The mount information write / etc / fstab the restart still take effect
echo "/ dev / vg0 / lv0 / mnt ext4 defaults 0 0" >> / etc / fstab
V. View LVM
Check the physical volume information: pvs, pvdisplay (Details)
Check volume group information: vgs, vgdisplay (Details)
See logical volume information: lvs, lvdisplay (Details)
Sixth, delete LVM
Remove LV: lvremove / dev / vg0 / lv0
Remove VG: vgremove vg0
Delete PV: pvremove / dev / sdb
Seven, drawing a logical volume
Logical stretching operation can be performed online, without uninstalling the logical volume
VG ensure that there is enough free space
vgs, vgdisplay
Logical extension
lvextend -L + 5G / dev / vg0 / lv0
Check the size of the expanded LV
lvs, lvdisplay
Update the file system
resize2fs / dev / vg0 / lv0
See the updated file system
df -h
Eight, drawing a volume group
VG will be added to the hard disk is formatted as PV
pvcreate / dev / sdd
Add a new PV to the specified volume group
vgextend vg0 / dev / sdd
Check the size of the expanded VG
vgs, vgdisplay
Nine, shrink a logical volume
Logical volume shrink operation must be performed offline, to uninstall the logical volume
Uninstall the logical volume has been mounted
umount / dev / vg0 / lv0
Shrink the file system (formerly lv0 to 10G)
e2fsck -f / dev / vg0 / lv0
resize2fs / dev / vg0 / lv0 3G
Reduced LV
lvreduce -L -7G / dev / vg0 / lv0
LV view after reduction
lvs, lvdisplay
Mounting
mount / dev / vg0 / lv0 / mnt
Ten, shrinking the volume group
PV will be removed from a specified group
vgreduce vg0 / dev / sdd
Check the size of the volume group after reduction
vgs, vgdisplay
Remove PV
pvremove / dev / sdd |
|
|
|