Detailed explanation of examples of logical volume management lvm-Linux Operation and Maintenance-php.cn

Logical Volume Management LVM

Create a logical volume

##1 Prepare partitions or hard disks

Here we use two hard disks of /dev/sdb and /dev/sdc and two partitions of /dev/sda9 and /dev/sda10, both in size. It's 1G and the disk is limited, so I don't want to be so picky.

Add partitions /dev/sda9, /dev/sda10

[root@centos7 ~]# fdisk /dev/sda Welcome to fdisk (util-linux 2.23.2). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): n All primary partitions are in use Adding logical partition 9 First sector (31885312-41943039, default 31885312): Using default value 31885312 Last sector, +sectors or +size{K,M,G} (31885312-41943039, default 41943039): +1G Partition 9 of type Linux and of size 1 GiB is set

Copy after login

Note that you need to change the partition type to Linux LVM

Command (m for help): t Partition number (1-9, default 9): 8e Partition number (1-9, default 9): 9 Hex code (type L to list all codes): 8e Changed type of partition 'Linux' to 'Linux LVM' Command (m for help):

Copy after login

Create /dev/sda10 in the same way.

[root@centos7 ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda9 8:9 0 1G 0 part └─sda10 8:10 0 1G 0 part sdb 8:16 0 1G 0 disk sdc 8:32 0 1G 0 disk

Copy after login

2 Create PV (physical volume)

The command format is: pvcreate DEVICE, you can create one device at a time , you can also create multiple devices at once.

View physical volume commands: pvdisplay (view detailed information), pvs (view simple information)

[root@centos7 ~]# pvcreate /dev/sda9 Physical volume "/dev/sda9" successfully created. [root@centos7 ~]# pvcreate /dev/sda10 /dev/sdb /dev/sdc Physical volume "/dev/sda10" successfully created. Physical volume "/dev/sdb" successfully created. Physical volume "/dev/sdc" successfully created.

Copy after login

View the physical volume and see that it has been successfully created.

[root@centos7 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda10 lvm2 --- 1.00g 1.00g /dev/sda9 lvm2 --- 1.00g 1.00g /dev/sdb lvm2 --- 1.00g 1.00g /dev/sdc lvm2 --- 1.00g 1.00g

Copy after login

3 Create a volume group (VG)

The command format is: vgcreate -s PE VGNAME (vg name ) DEVICE (device name)

-s: Specify the physical extension block size, which is the size of the PE

View commands: vgs, vgdisplay

[root@centos7 ~]# vgcreate -s 16M vg0 /dev/sda9 /dev/sda10 /dev/sdb /dev/sdc Volume group "vg0" successfully created

Copy after login

Check it out

[root@centos7 ~]# vgs VG #PV #LV #SN Attr VSize VFree vg0 4 0 0 wz--n- 3.94g 3.94g

Copy after login

and then look at the details

[root@centos7 ~]# vgdisplay --- Volume group --- VG Name vg0 System ID Format lvm2 Metadata Areas 4 Metadata Sequence No 1 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 4 Act PV 4 VG Size 3.94 GiB PE Size 16.00 MiB Total PE 252 Alloc PE / Size 0 / 0 Free PE / Size 252 / 3.94 GiB VG UUID qmoIMg-5wQR-GKCS-dpq9-HLrt-zVIi-JBC9ZX

Copy after login

Everything is as expected, the size is about 4G, which is exactly two partitions and two The sum of hard drives.

4 Create a logical volume (LV)

The command format is: lvcreate -n LVNAME (specify LV name) -L SIZE (specify LV size) vg0 (VG to be used)

-l Specify PE size

View command (similar to PV, VG): lvs, lvdisplay

[root@centos7 ~]# lvcreate -n lv0 -L 3G vg0 Logical volume "lv0" created.

Copy after login

Created successfully, check

[root@centos7 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv0 vg0 -wi-a----- 3.00g

Copy after login

and then check the details

[root@centos7 ~]# lvdisplay --- Logical volume --- LV Path /dev/vg0/lv0 LV Name lv0 VG Name vg0 LV UUID 622i7m-uy6s-3nZI-8xSb-sxrR-cZzz-C9pwkd LV Write Access read/write LV Creation host, time centos7.3.loacl, 2017-04-25 16:25:13 +0800 LV Status available # open 0 LV Size 3.00 GiB Current LE 192 Segments 4 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:0

Copy after login

You can confirm that it has been successfully created.

Now you can use /dev/vg0/lv0 as a hard disk.

Now look at the disk information, it has changed.

[root@centos7 ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT fd0 2:0 1 4K 0 disk sda 8:0 0 20G 0 disk ├─sda9 8:9 0 1G 0 part │ └─vg0-lv0 253:0 0 3G 0 lvm └─sda10 8:10 0 1G 0 part └─vg0-lv0 253:0 0 3G 0 lvm sdb 8:16 0 1G 0 disk └─vg0-lv0 253:0 0 3G 0 lvm sdc 8:32 0 1G 0 disk └─vg0-lv0 253:0 0 3G 0 lvm

Copy after login

You can see that the added partition and hard disk already belong to vg0-lv0.

5 Create the file system and format it

mkfs.ext4 /dev/vg0/lv0 [root@centos7 ~]# mkfs.ext4 /dev/vg0/lv0

Copy after login

6 Mount using

[root@centos7 ~]# mkdir /mnt/lv0 [root@centos7 ~]# mount /dev/vg0/lv0 /mnt/lv0

Copy after login

Second expansion LV

Extension command format:

lvextend -L 100G /dev/vg0/lv0 lvextend -l +100G /dev/vg0/lv0 lvextend -l +100%FREE /dev/vg0/lv0

Copy after login

Note –L is how much to extend, -l is how much to extend (increase), +100%FREE is to extend 100% of the remaining vg, which can be adjusted according to personal circumstances Make your selection.

Since vg0 still reserves nearly 1G space, now expand lv0

1 Let’s check the original LV first

[root@centos7 ~]# vgs VG #PV #LV #SN Attr VSize VFree vg0 4 1 0 wz--n- 3.94g 960.00m

Copy after login

2 Extend LV

[root@centos7 ~]# lvextend -r -l +100%FREE /dev/vg0/lv0

Copy after login

-r is resizefs. It’s so convenient to do it in one step

Or It's a little troublesome, step by step

[root@centos7 ~]# lvextend -l +100%FREE /dev/vg0/lv0 Size of logical volume vg0/lv0 changed from 3.00 GiB (192 extents) to 3.94 GiB (252 extents). Logical volume vg0/lv0 successfully resized.

Copy after login

3 Come down and redefine the file system size

ext series file system redefinition : resize2fs /dev/vg0/lv0

xfs series file system redefinition: xfs_growfs /dev/vg0/lv0

[root@centos7 ~]# resize2fs /dev/vg0/lv0 resize2fs 1.42.9 (28-Dec-2013) Filesystem at /dev/vg0/lv0 is mounted on /mnt/lv0; on-line resizing required old_desc_blocks = 1, new_desc_blocks = 1 The filesystem on /dev/vg0/lv0 is now 1032192 blocks long.

Copy after login

4 Check the file System completion (optional)

[root@centos7 ~]# fsck.ext4 /dev/vg0/lv0 e2fsck 1.42.9 (28-Dec-2013) /dev/vg0/lv0: clean, 20/262144 files, 35918/1032192 blocks

Copy after login

5 Confirm the logical volume size

[root@centos7 ~]# df -h /dev/vg0/lv0 Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg0-lv0 3.9G 12M 3.6G 1% /mnt/lv0

Copy after login

It is obvious that the expansion has been successful.

6 Mount using

[root@centos7 ~]# mount -o remount /dev/vg0/lv0

Copy after login

Three reduced LV

1 Backup data

Although there is generally no loss of data, for the sake of safety . It's better to back up first.

Look at the existing data in the /mnt/lv0 directory

[root@centos7 ~]# ls /mnt/lv0/ lost+found myfile2 myfile4 myfile6 myfile8 myfile1 myfile3 myfile5 myfile7 myfile9 [root@centos7 ~]# mkdir /backup [root@centos7 ~]# cp -a /mnt/lv0/* /backup/

Copy after login

##2 Uninstall /dev/vg0/lv0

[root@centos7 ~]# umount /mnt/lv0/

Copy after login

3 Check the file systeme2fsck -f /dev/vg0/lv0 Redefining the file system Disk completion must be checked before size

[root@centos7 ~]# e2fsck -f /dev/vg0/lv0 e2fsck 1.42.9 (28-Dec-2013) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/vg0/lv0: 20/262144 files (0.0% non-contiguous), 35918/1032192 blocks

Copy after login

4下来重定义文件系统大小

resize2fs /dev/vg0/lv0 2G #2G位缩减后的LV 大小。

[root@centos7 ~]# resize2fs /dev/vg0/lv0 2G resize2fs 1.42.9 (28-Dec-2013) Resizing the filesystem on /dev/vg0/lv0 to 524288 (4k) blocks. The filesystem on /dev/vg0/lv0 is now 524288 blocks long.

Copy after login

5 缩减LV

lvreduce -L 2G /dev/vg0/lv0 #缩减到2G

[root@centos7 ~]# lvreduce -L 2G /dev/vg0/lv0 WARNING: Reducing active logical volume to 2.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce vg0/lv0? [y/n]: y Size of logical volume vg0/lv0 changed from 3.94 GiB (252 extents) to 2.00 GiB (128 extents). Logical volume vg0/lv0 successfully resized.

Copy after login

6 挂载使用

mount /dev/vg0/lv0 /mnt/lv0 [root@centos7 ~]# mount /dev/vg0/lv0 /mnt/lv0/

Copy after login

查看磁盘挂载情况

[root@centos7 ~]# df -h /dev/vg0/lv0 Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg0-lv0 2.0G 9.0M 1.8G 1% /mnt/lv0

Copy after login

7 确认数据是否丢失

现在再来开心目录/mnt/lv0 的内容

[root@centos7 ~]# ls /mnt/lv0/ lost+found myfile2 myfile4 myfile6 myfile8 myfile1 myfile3 myfile5 myfile7 myfile9

Copy after login

很完美，数据并没有丢失！

The above is the detailed content of Detailed explanation of examples of logical volume management lvm. For more information, please follow other related articles on the PHP Chinese website!