[Linux]LVM扩展卷 | 易学教程

LVM

LVM是逻辑盘卷管理（Logical Volume Manager）的简称，它是Linux环境下对磁盘分区进行管理的一种机制，LVM是建立在硬盘和分区之上的一个逻辑层，来提高磁盘分区管理的灵活性。LVM是在磁盘分区和文件系统之间添加的一个逻辑层，来为文件系统屏蔽下层磁盘分区布局，提供一个抽象的盘卷，在盘卷上建立文件系统。物理卷（physical volume）物理卷就是指硬盘分区或从逻辑上与磁盘分区具有同样功能的设备（如RAID），是LVM的基本存储逻辑块，但和基本的物理存储介质（如分区、磁盘等）比较，却包含有与LVM相关的管理参数。

优势：能够在线扩容当前的分区容量。
结构：在整个LVM结构当中以此分为：“物理卷、物理卷分区、卷组、逻辑卷”，下面我详细解释一下这四种结构：

物理卷：Physical Volume，简称PV，一个物理卷只不过是一个有LVM管理数据添加在里面的物理存储介质。要使用LVM系统，首先对要用于LVM的磁盘进行初始化，初始化的目的就是将磁盘或分区标识为LVM 的物理卷。使用pvcreate 命令可以将一个磁盘标记为 LVM 物理卷。
物理分区：Physical Extents，简称PE，LVM将每个物理卷分别叫做物理分区的可寻址存储单元，存储单元的大小通常为几MB。磁盘的开头部分为LVM元数据，之后从索引为零开始，每个物理分区的索引依次递增一，按顺序进行分配。
卷组：Volume Group，简称VG，物理卷可以组织为卷组。卷组可以由一个或多个物理卷组成，同时系统中可以有多个卷组。创建了卷组之后，该卷组（而不是磁盘）便是表示数据存储的实体。因此，尽管以前是将磁盘从一个系统移动到另一个系统，使用了 LVM 之后，会将卷组从一个系统移动到另一个系统。出于这种原因，通常在一个系统上创建多个卷组会比较方便。
逻辑分区：Logical Extents，简称LE，逻辑卷的基本分配单元称为逻辑分区。逻辑分区映射到物理分区，因此，如果物理分区的尺寸小为4MB，那么逻辑分区的尺寸也将为4MB。逻辑卷的大小取决于所分配的逻辑分区数量。

生产环境

[root@Nexus3 ~]# cat /etc/redhat-release 
CentOS Linux release 7.7.1908 (Core)
[root@Nexus3 ~]# lvm version
  LVM version:     2.02.185(2)-RHEL7 (2019-05-13)
  Library version: 1.02.158-RHEL7 (2019-05-13)
  Driver version:  4.37.1

硬盘扩容20G->100G

[root@Nexus3 ~]# df -hT
Filesystem              Type      Size  Used Avail Use% Mounted on
devtmpfs                devtmpfs  3.9G     0  3.9G   0% /dev
tmpfs                   tmpfs     3.9G     0  3.9G   0% /dev/shm
tmpfs                   tmpfs     3.9G  8.8M  3.9G   1% /run
tmpfs                   tmpfs     3.9G     0  3.9G   0% /sys/fs/cgroup
-----/dev/mapper/centos-root是我们需要扩的卷-------------------------
/dev/mapper/centos-root xfs        17G  1.2G   16G   7% /
/dev/sda1               xfs      1014M  136M  879M  14% /boot
tmpfs                   tmpfs     799M     0  799M   0% /run/user/0

查看本地物理硬盘

[root@Nexus3 ~]# fdisk -l
-----磁盘容量100G-------------------------
Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000c35ff

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
-----正在使用18.2G，我们需要将此硬盘扩容-------------------------
Disk /dev/mapper/centos-root: 18.2 GB, 18249416704 bytes, 35643392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

硬盘分区

根据实际情况选择自己的硬盘

[root@Nexus3 ~]# 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.

-----列出当前分区-------------------------
Command (m for help): p

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000c35ff

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
-----注意后面Id System 后面用到-------------------------
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
-----创建分区n，一路回车就会创建sda3全部容量-------------------------
Command (m for help): n
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p): 
Using default response p
Partition number (3,4, default 3): 
First sector (41943040-209715199, default 41943040): 
Using default value 41943040
Last sector, +sectors or +size{K,M,G} (41943040-209715199, default 209715199): 
Using default value 209715199
Partition 3 of type Linux and of size 80 GiB is set
-----验证分区-------------------------
Command (m for help): p

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000c35ff

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
-----看看后面Id System需要修改-------------------------
/dev/sda3        41943040   209715199    83886080   83  Linux
-----修改Id-------------------------
Command (m for help): t
Partition number (1-3, default 3): 
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000c35ff

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
/dev/sda3        41943040   209715199    83886080   8e  Linux LVM
-----保存！！！！！-------------------------
Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
-----同步磁盘状态-------------------------
[root@Nexus3 ~]# partprobe

创建物理卷

pvcreate

-----查询当前PV-------------------------
[root@Nexus3 ~]# pvdisplay 
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               <19.00 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4863
  Free PE               0
  Allocated PE          4863
  PV UUID               2MrxDf-dTQK-I7iK-5VUs-bcrv-Af2t-fVaAiL
-----创建新的PV-------------------------
[root@Nexus3 ~]# pvcreate /dev/sda3 
  Physical volume "/dev/sda3" successfully created.
[root@Nexus3 ~]# pvdisplay 
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               <19.00 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4863
  Free PE               0
  Allocated PE          4863
  PV UUID               2MrxDf-dTQK-I7iK-5VUs-bcrv-Af2t-fVaAiL

-----这个是我们创建的-------------------------   
  "/dev/sda3" is a new physical volume of "80.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sda3
  VG Name               
  PV Size               80.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               kfO9Yc-ToQb-2vnf-8muc-MNsZ-oxJV-vi1vVe

扩展卷组

vgextend

-----查看当前VG-------------------------
[root@Nexus3 ~]# vgdisplay 
  --- Volume group ---
-----VG Name需要用到-------------------------
  VG Name               centos
  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               <19.00 GiB
  PE Size               4.00 MiB
  Total PE              4863
  Alloc PE / Size       4863 / <19.00 GiB
  Free  PE / Size       0 / 0   
  VG UUID               Wx79ds-a3LO-VhXo-HJdk-fr0X-C9UX-KOqfSK
-----扩展卷组-------------------------
[root@Nexus3 ~]# vgextend centos /dev/sda3 
  Volume group "centos" successfully extended

逻辑卷扩展

lvextend -l +100%free /mapper/centos-root> #前面df -hT看到的信息

-----查看逻辑卷-------------------------
[root@Nexus3 ~]# lvdisplay 
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                bgsynr-YUZE-LX2j-NIgG-sqqU-wVxb-GIZDg7
  LV Write Access        read/write
  LV Creation host, time localhost, 2019-11-22 14:16:37 +0800
  LV Status              available
  # open                 2
  LV Size                2.00 GiB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1
   
-----我们需要扩展该卷-------------------------
  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                lkRm4c-8g6X-ZWm2-Y86h-aKXs-i2lN-ZKdGaD
  LV Write Access        read/write
  LV Creation host, time localhost, 2019-11-22 14:16:37 +0800
  LV Status              available
  # open                 1
  LV Size                <17.00 GiB
  Current LE             4351
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
-----扩充-------------------------
[root@Nexus3 ~]# lvextend -l +100%free /dev/mapper/centos-root 
  Size of logical volume centos/root changed from <17.00 GiB (4351 extents) to 96.99 GiB (24830 extents).
  Logical volume centos/root successfully resized.

动态格式化扩容磁盘

[root@Nexus3 ~]# xfs_growfs /dev/mapper/centos-root 
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1113856 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=4455424, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 4455424 to 25425920

验证

[root@Nexus3 ~]# df -hT
Filesystem              Type      Size  Used Avail Use% Mounted on
devtmpfs                devtmpfs  3.9G     0  3.9G   0% /dev
tmpfs                   tmpfs     3.9G     0  3.9G   0% /dev/shm
tmpfs                   tmpfs     3.9G  8.9M  3.9G   1% /run
tmpfs                   tmpfs     3.9G     0  3.9G   0% /sys/fs/cgroup
-----100G-------------------------
/dev/mapper/centos-root xfs        97G  1.2G   96G   2% /
/dev/sda1               xfs      1014M  136M  879M  14% /boot
tmpfs                   tmpfs     799M     0  799M   0% /run/user/0

END

来源：https://www.cnblogs.com/leoshi/p/12355497.html

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