The management of Linux LVM

The management of LVM

Let's first introduce the DM, and the rationale of the logical Volume:

Dm:device Mapper Device Mapping, a mechanism for providing logical devices

1, the combination of multiple physical devices into a logical device

2, the implementation of RAID,LVM2 (logical Volume 2) function

3, the core of LVM2 function realization

4, to achieve dynamic expansion and reduce the file system space

5, supporting the function of mirroring

DM How to organize multiple physical devices into logical devices:

Linear (linear devices), mirror (similar to mirrors), snapshot (snapshots), multipath (multipath)

Snapshot: Access another path to the same data. Implementing Data Backup

Multiple physical disks in a DM are organized into a logical device that requires the creation of similar logical partitions to be used on logical devices.

Physical volume pv:physical Volume (that is, multiple physical devices)

Volume Group Vg:volume Group (logical device, PV combination)

Logical volumes: Logical Volume (dynamically extended partitions)

Each logical volume is a separate file system that has two boundaries: physical boundaries, logical boundaries

Snapshots can be created on logical volumes, and logical volumes and snapshots are stored in VG.

The volume group is composed of a PE, and PE transition to logical volume, is called VE

Pe:physial Extend, Physical disk area. Physical volumes can only become PE when they are joined to a volume group

Le:logical Extend, Logical Disk area

Next, let's talk about the management of logical volumes:

It is recommended that you create logical volumes on RAID. (Hardware RAID)

Pv

Pvcreate: Create PV.

-F: Force create

Example: # pvcreate/dev/sda{10,11}

Pvscan | PVS: Scans the current system a total number of PV

Pvdisplay: View PV Details, you can specify a PV

Example: # PVDISPLAY/DEV/SDA10

Pvmove: Move data from the disk in which the data is stored to another disk area

Example: # PVMOVE/DEV/SDA10

Pvremove: Erase the source data from a panel

Example: # pvremove/dev/sda10 (delete/dev/sda10 panel)

Preparing to create PV requires a few disks and a disk type of 8e, which is the LVM type.

Vg:

Vgcreate: Creating VG

-S #: Specify PE size, default to 4M

Example: # Vgcreate myvg/dev/sda{10,11}

Vgremove: Remove VG

Example: # Vgremove MYVG

Vgextend: Extend the size of the VG, that is, add a PE

Example: # Vgextend Myvg/dev/sda12

Vgreduce: Reduce the size of the VG, that is, the process of removing a PE

Example: # Vgreduce MYVG/DEV/SDA10

VGS: See how many volume groups are on the current system

Vgdisplay: View the details of the VG to specify a VG

Lv:

Lvcreate: Creating LV

-N: Specify name

-L: Specify size

Lvcreate-n lv_name-l #G Vg_name

Example: # lvcreat-l 50m-n TESTLV MYVG

Lvremove: Remove LV

Example: # LVREMOVE/DEV/MYVG/TESTLV