2018-10-29 Redhat7 lv逻辑卷管理

LVM是在硬盘分区和文件系统之间添加了一个逻辑层，用户不必关心物理硬盘设备的底层架构和布局，可以实现对硬盘分区的动态调整。

为了验证逻辑卷与物理硬盘无关的特性，在虚拟机增加两块硬盘，然后重启虚拟机。这时还看不到这两块硬盘。

[root@localhost ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   18G  3.2G   15G  18% /
devtmpfs               905M     0  905M   0% /dev
tmpfs                  914M  140K  914M   1% /dev/shm
tmpfs                  914M  9.0M  905M   1% /run
tmpfs                  914M     0  914M   0% /sys/fs/cgroup
/dev/sda1              497M  119M  379M  24% /boot
/dev/sr0               3.5G  3.5G     0 100% /mnt/cdrom

这里sdb和sdc就是新加的硬盘

[root@localhost Desktop]# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sda2  /dev/sdb  /dev/sdc

现在在sdb和sdc启用lvm

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

把sdb和sdc加入storage卷组，sdb是10G，sdc是2G，可以看到下面显示storage是12G

[root@localhost Desktop]# vgcreate storage /dev/sdb /dev/sdc
  Volume group "storage" successfully created
[root@localhost Desktop]# vgdisplay
  --- Volume group ---
  VG Name               rhel
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               19.51 GiB
  PE Size               4.00 MiB
  Total PE              4994
  Alloc PE / Size       4994 / 19.51 GiB
  Free  PE / Size       0 / 0   
  VG UUID               Hgh6Rz-Jw3s-89rg-rlTb-ydtT-o0jD-CzRJfx

  --- Volume group ---
  VG Name               storage
  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               11.99 GiB
  PE Size               4.00 MiB
  Total PE              3070
  Alloc PE / Size       0 / 0   
  Free  PE / Size       3070 / 11.99 GiB
  VG UUID               GG1aS3-kXkF-YeGn-31rE-BFEY-Y9sT-8dpd5l

在storage里切割出150M的一个逻辑卷vo，这里-l 表示使用PE，37个PE = 4M*37=148M，或者使用-L 150M直接指定大小，因为PE大小默认为4M，结果会变成152M。

[root@localhost Desktop]# lvcreate -n vo -l 37 storage
  Logical volume "vo" created
[root@localhost Desktop]# lvdisplay
....

  --- Logical volume ---
  LV Path                /dev/storage/vo
  LV Name                vo
  VG Name                storage
  LV UUID                VIUdJC-hziC-14da-76Y1-E1UO-gxTa-UYmMsf
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2018-10-29     17:28:21 +0000
  LV Status              available
  # open                 0
  LV Size                148.00 MiB
  Current LE             37
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2

[root@localhost Desktop]#

格式化为ext4，并挂载到/linuxlv目录下

[root@localhost Desktop]# mkfs.ext4 /dev/storage/vo
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
38000 inodes, 151552 blocks
7577 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
2000 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 Desktop]# mkdir /linuxlv
[root@localhost Desktop]# mount /dev/storage/vo /linuxlv

可以看到已经生效了

[root@localhost Desktop]# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root    18G  3.1G   15G  18% /
devtmpfs                905M     0  905M   0% /dev
tmpfs                   914M  140K  914M   1% /dev/shm
tmpfs                   914M  8.9M  905M   1% /run
tmpfs                   914M     0  914M   0% /sys/fs/cgroup
/dev/sda1               497M  119M  379M  24% /boot
/dev/sr0                3.5G  3.5G     0 100% /run/media    /root/RHEL-7.0 Server.x86_64
/dev/mapper/storage-vo  140M  1.6M  128M   2% /linuxlv

写入配置文件，使其启动生效，也可vim /etc/fstab文件直接增加一行：

[root@localhost Desktop]# echo "/dev/storage/vo /linuxlv ext4 defaults 0 0" >> /etc/fstab

现在尝试扩展vo到300M
首先卸载设备

[root@localhost Desktop]# umount /linuxlv

然后扩展到300M

[root@localhost Desktop]# lvextend -L 300M /dev/storage/vo
  Extending logical volume vo to 300.00 MiB
  Logical volume vo successfully resized

检查硬盘完整性，重置容量

[root@localhost Desktop]# e2fsck -f /dev/storage/vo
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/storage/vo: 11/38000 files (0.0% non-contiguous),     10453/151552 blocks
[root@localhost Desktop]# resize2fs /dev/storage/vo
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/storage/vo to 307200 (1k) blocks.
The filesystem on /dev/storage/vo is now 307200 blocks long.

重新挂载，再看下vo卷大小已经更改了。

[root@localhost Desktop]# mount -a
[root@localhost Desktop]# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root    18G  3.1G   15G  18% /
devtmpfs                905M     0  905M   0% /dev
tmpfs                   914M  140K  914M   1% /dev/shm
tmpfs                   914M  8.9M  905M   1% /run
tmpfs                   914M     0  914M   0% /sys/fs/cgroup
/dev/sda1               497M  119M  379M  24% /boot
/dev/sr0                3.5G  3.5G     0 100% /run/media    /root/RHEL-7.0 Server.x86_64
/dev/mapper/storage-vo  287M  2.1M  266M   1% /linuxlv
[root@localhost Desktop]#

缩小逻辑卷vo到120M。由于缩小硬盘容量有丢失数据的风险，所以在生产环境中要先备份数据，检查硬盘完整性，再进行缩小容量的操作。记得先卸载设备。

[root@localhost Desktop]# umount /linuxlv
[root@localhost Desktop]# e2fsck -f /dev/storage/vo
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/storage/vo: 11/76000 files (0.0% non-contiguous), 15759/307200 blocks
[root@localhost Desktop]# resize2fs /dev/storage/vo 120M
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/storage/vo to 122880 (1k) blocks.
  The filesystem on /dev/storage/vo is now 122880 blocks long.

重新挂载看下，vo卷已经减少到120M了。

[root@localhost Desktop]# mount -a
[root@localhost Desktop]# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root    18G  3.1G   15G  18% /
devtmpfs                905M     0  905M   0% /dev
tmpfs                   914M  140K  914M   1% /dev/shm
tmpfs                   914M  8.9M  905M   1% /run
tmpfs                   914M     0  914M   0% /sys/fs/cgroup
/dev/sda1               497M  119M  379M  24% /boot
/dev/sr0                3.5G  3.5G     0 100% /run/media    /root/RHEL-7.0 Server.x86_64
/dev/mapper/storage-vo  113M  1.6M  103M   2% /linuxlv

一路删除逻辑卷-VG-PV：

[root@localhost ~]# umount /mnt/vo
[root@localhost ~]# lvremove /dev/storage/vo
Do you really want to remove active logical volume vo? [y/n]: y
Logical volume "vo" successfully removed
[root@localhost ~]# vgremove storage
  Volume group "storage" successfully removed
[root@localhost ~]# pvremove /dev/sdc
  Labels on physical volume "/dev/sdc" successfully wiped
[root@localhost ~]# pvscan
  PV /dev/sda2   VG rhel            lvm2 [19.51 GiB / 0    free]
  PV /dev/sdb                       lvm2 [4.00 GiB]
  Total: 2 [23.51 GiB] / in use: 1 [19.51 GiB] / in no VG: 1 [4.00 GiB]

2018-10-29 Redhat7 lv逻辑卷管理

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