lvm逻辑卷的操作--学习笔记

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风山渐1 2020-02-25 17:40:44 博主文章分类：《linux就该这么学》笔记 ©著作权

文章标签 linux lvm 文章分类 运维

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本次实验环境是redhat7.0系统

逻辑卷管理器是linux系统用于对硬盘分区进行管理的一种机制，初衷是为了解决硬盘设备在创建分区后不易修改分区大小的缺陷。它提供了一个抽象的卷组，可以把多块硬盘进行卷组合并，用户不必关系物理硬盘设备的底层架构和布局，就可以实现对硬盘分区的动态调整。

常用的命令

作用	物理卷管理	卷组管理	逻辑卷管理
扫描	pvscan	vgscan	lvscan
建立	pvcreate	vgcreate	lvcreate
显示	pvdisplay	vgdisplay	lvdisplay
删除	pvremove	vgremove	lvremove
扩展		vgextend	lvextend
缩小		vgreduce	lvreduce

创建pv

将/dev/sdb /dev/sdc创建成pv

[root@localhost mnt]# pvcreate /dev/sdb /dev/sdc
  Physical volume "/dev/sdb" successfully created
  Physical volume "/dev/sdc" successfully created

查看pv

[root@localhost mnt]# pvdisplay 
  --- Physical volume ---
  PV Name               /dev/sdb
  VG Name               vg1
  PV Size               5.00 GiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              1279
  Free PE               1279
  Allocated PE          0
  PV UUID               7HM45W-ceIl-sEFh-9uj3-cz4W-jZ5Z-cWavvd
   
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               vg1
  PV Size               5.00 GiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              1279
  Free PE               1279
  Allocated PE          0
  PV UUID               B1oEjB-UJcE-l1Lk-9DTI-BWy3-2FdC-dmdgbI

创建vg

创建一个vg，命名为vg1

[root@localhost mnt]# vgcreate vg1 /dev/sdb /dev/sdc
  Volume group "vg1" successfully created

查看vg

[root@localhost mnt]# vgdisplay 
  --- Volume group ---
  VG Name               vg1
  System ID             
  Format                lvm2
  Metadata Areas        2
  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                2
  Act PV                2
  VG Size               9.99 GiB
  PE Size               4.00 MiB
  Total PE              2558
  Alloc PE / Size       0 / 0   
  Free  PE / Size       2558 / 9.99 GiB
  VG UUID               m3pfeB-v3os-itGn-RYKz-gYLi-dHqY-fRAQ2L

创建一个lv

创建一个大小为150M的逻辑卷对逻辑卷进行切割时有两种计量单位：

以容量为单位，所使用的参数为-L。例如：-L 150M
以基本单元的个数为单位，使用的参数为-l，默认基本单元是4MB。例如 -l 10 为4MB x 10 =40MB

[root@localhost mnt]# lvcreate -n lv1 -L 150M vg1
 Logical volume "lv1" created

查看lv

[root@localhost mnt]# lvdisplay 
  --- Logical volume ---
  LV Path                /dev/vg1/lv1
  LV Name                lv1
  VG Name                vg1
  LV UUID                EuYC0s-eXZo-3Vlq-xOQF-Suej-AkLY-vkQbv2
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2020-02-25 17:06:06 +0800
  LV Status              available
  # open                 0
  LV Size                152.00 MiB
  Current LE             38
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2

对lv进行格式化，挂载使用

[root@localhost mnt]# mkfs.ext4  /dev/vg1/lv1 
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
38912 inodes, 155648 blocks
7782 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=33816576
19 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks: 
	8193, 24577, 40961, 57345, 73729

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done 


[root@localhost mnt]# mkdir lv1
[root@localhost mnt]# mount /dev/vg1/lv1 /mnt/lv1/
[root@localhost mnt]# df -Th
Filesystem            Type      Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root xfs        18G  3.0G   15G  17% /
devtmpfs              devtmpfs  1.5G     0  1.5G   0% /dev
tmpfs                 tmpfs     1.5G  140K  1.5G   1% /dev/shm
tmpfs                 tmpfs     1.5G  8.9M  1.5G   1% /run
tmpfs                 tmpfs     1.5G     0  1.5G   0% /sys/fs/cgroup
/dev/sr0              iso9660   3.5G  3.5G     0 100% /media/cdrom
/dev/sda1             xfs       497M  119M  379M  24% /boot
/dev/mapper/vg1-lv1   ext4      144M  1.6M  132M   2% /mnt/lv1

将挂载目录写入到/etc/fstab,永久生效

[root@localhost mnt]# vim /etc/fstab 
/dev/vg1/lv1 /mnt/lv1 ext4 defaults 0 0

对lv扩容

扩容之前，先卸载lv

[root@localhost mnt]# umount /dev/vg1/lv1

扩容到200M

[root@localhost mnt]# lvextend -L 200M /dev/vg1/lv1 
  Extending logical volume lv1 to 200.00 MiB
  Logical volume lv1 successfully resized

检查硬盘完整性

[root@localhost mnt]# e2fsck -f /dev/vg1/lv1
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/vg1/lv1: 11/38912 files (0.0% non-contiguous), 10567/155648 blocks

重置硬盘容量

[root@localhost mnt]# resize2fs /dev/vg1/lv1
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg1/lv1 to 204800 (1k) blocks.
The filesystem on /dev/vg1/lv1 is now 204800 blocks long.

重新挂载，查看状态

[root@localhost mnt]# mount -a
[root@localhost mnt]# df -Th
Filesystem            Type      Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root xfs        18G  3.0G   15G  17% /
devtmpfs              devtmpfs  1.5G     0  1.5G   0% /dev
tmpfs                 tmpfs     1.5G  140K  1.5G   1% /dev/shm
tmpfs                 tmpfs     1.5G  8.9M  1.5G   1% /run
tmpfs                 tmpfs     1.5G     0  1.5G   0% /sys/fs/cgroup
/dev/sr0              iso9660   3.5G  3.5G     0 100% /media/cdrom
/dev/sda1             xfs       497M  119M  379M  24% /boot
/dev/mapper/vg1-lv1   ext4      190M  1.6M  175M   1% /mnt/lv1

对lv缩容

缩容之前，做好数据备份，先卸载lv

[root@localhost mnt]# umount /dev/vg1/lv1

检查硬盘完整性

[root@localhost mnt]# e2fsck -f /dev/vg1/lv1
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/vg1/lv1: 11/51200 files (0.0% non-contiguous), 12115/204800 blocks

容量减小到100M

[root@localhost mnt]# resize2fs /dev/vg1/lv1 100M
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg1/lv1 to 102400 (1k) blocks.
The filesystem on /dev/vg1/lv1 is now 102400 blocks long.

[root@localhost mnt]# lvreduce -L 100M /dev/vg1/lv1 
  WARNING: Reducing active logical volume to 100.00 MiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv1? [y/n]: y
  Reducing logical volume lv1 to 100.00 MiB
  Logical volume lv1 successfully resized

重新挂载，查看状态

[root@localhost mnt]# mount -a
[root@localhost mnt]# df -Th
Filesystem            Type      Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root xfs        18G  3.0G   15G  17% /
devtmpfs              devtmpfs  1.5G     0  1.5G   0% /dev
tmpfs                 tmpfs     1.5G  140K  1.5G   1% /dev/shm
tmpfs                 tmpfs     1.5G  8.9M  1.5G   1% /run
tmpfs                 tmpfs     1.5G     0  1.5G   0% /sys/fs/cgroup
/dev/sr0              iso9660   3.5G  3.5G     0 100% /media/cdrom
/dev/sda1             xfs       497M  119M  379M  24% /boot
/dev/mapper/vg1-lv1   ext4       93M  1.6M   85M   2% /mnt/lv1

创建逻辑卷快照

快照特点：

快照卷的容量必须等同于逻辑卷的容量
快照卷仅一次有效，一旦执行还原操作后会被删除

查看vg状态，确保有足够的容量创建快照

[root@localhost mnt]# vgdisplay 
  --- Volume group ---
  VG Name               vg1
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               9.99 GiB
  PE Size               4.00 MiB
  Total PE              2558
  Alloc PE / Size       25 / 100.00 MiB
  Free  PE / Size       2533 / 9.89 GiB
  VG UUID               m3pfeB-v3os-itGn-RYKz-gYLi-dHqY-fRAQ2L

对lv1创建快照, -s 创建快照；-n 快照名称；-L 快照的容量创建快照时，不用卸载lv

[root@localhost mnt]# lvcreate -s -n snap-lv1 -L 100M /dev/vg1/lv1
  Logical volume "snap-lv1" created

恢复快照，恢复之前先卸载lv

[root@localhost mnt]# umount /dev/vg1/lv1 
[root@localhost mnt]# lvconvert --merge /dev/vg1/snap-lv1 
  Merging of volume snap-lv1 started.
  lv1: Merged: 100.0%
  Merge of snapshot into logical volume lv1 has finished.
  Logical volume "snap-lv1" successfully removed

重新挂载lv，查看数据

删除lv、vg、pv

如果不再使用lvm，执行删除操作，删除的顺序是：lv-vg-pv，顺序不能错，不然删除不了,删除之间先卸载lv

[root@localhost mnt]# lvremove /dev/vg1/lv1 
Do you really want to remove active logical volume lv1? [y/n]: y
  Logical volume "lv1" successfully removed

[root@localhost mnt]# vgremove vg1
  Volume group "vg1" successfully removed

[root@localhost mnt]# pvremove /dev/sdb /dev/sdc
  Labels on physical volume "/dev/sdb" successfully wiped
  Labels on physical volume "/dev/sdc" successfully wiped