Introduction : LVM is a mechanism for managing disk partitions in the Linux environment. It is a logical layer built on top of hard disks and partitions and under the file system, which can improve the flexibility of disk partition management.

introduce

Many Linux users will encounter such a dilemma when installing the operating system: how to accurately evaluate and allocate the capacity of each hard disk partition. If the initial evaluation is not accurate, once the system partition is not enough, it may have to back up, delete related data, or even be forced to renew Plan partitions and reinstall the operating system to meet the needs of the application system.

LVM is a mechanism for managing disk partitions in the Linux environment. It is a logical layer built on top of hard disks and partitions and under the file system, which can improve the flexibility of disk partition management. The default partition format of KYLIN V3 is the LVM logical volume format. It should be noted that the /boot partition cannot be created based on LVM and must be independent.

The following figure parses the entire process of LVM creation.

Detailed configuration

lab environment

First create two partitions sdb1 1G, sdb2 2G from the empty hard disk sdb. Prepare for the next LVM.

In order to facilitate maintenance and management later, remember to add a mark to the partition, so that even if you are not there, others will not easily move this area when they see the mark. The logo of LVM is 8e, remember to press w after setting to save.

Create logical volumes

Convert the two newly created partitions /dev/sdb1 /dev/sdb2 into physical volumes, mainly adding LVM attribute information and dividing PE storage units.

Create a volume group vgdata and add the two physical volumes just created to the volume group. It can be seen that the default PE size is 4MB, and PE is the smallest storage unit of the volume group. The size can be modified by the –s parameter.

Split 500M from the physical volume vgdata to the new logical volume lvdata1.

Create an ext4 file system on the logical volume lvdata1 using the mkfs.ext4 command.

Mount the created file system /data1 to /data1. (After creation, a soft connection named "Volume Group-Logical Volume" will be generated in /dev/mapper/)

To facilitate automatic mounting after server restart, you need to add the created file system mount information to /etc/fstab. UUID can be queried through the blkid command.

为了查看/etc/fstab是否设置正确,可以先卸载逻辑卷data1,然后使用mount –a 使内核重新读取/etc/fstab,看是否能够自动挂载.

逻辑卷lvdata1不够用了，如何扩展

给逻辑卷增加空间并不会影响以前空间的使用，所以无需卸载文件系统，直接通过命令lvextend –L +500M /dev/vgdata/lvdata1或者lvextend –l 2.5G /dev/vgdata/lvdata1 给lvdata1增加500M空间（lvdata1目前是2G空间）设置完成之后，记得使用resize2fs命令来同步文件系统。