Linux系统（１＋Ｘ） - LVM逻辑卷管理 - 《Linux 基础知识》

规划节点
- 基础准备
- 案例实施

规划节点

Linux操作系统的单节点规划。
　节点规划

IP	主机名	节点
192.168.200.10	ｋｖｍ	Linux服务器节点

基础准备

　添加硬盘
　　在VMwareWorkstation中的虚拟机设置界面，单击下方“添加”按钮，选择“硬盘”，然后单击右下角“下一步”按钮。

　１，选择SCSI（S）磁盘，单击右下角“下一步”按钮。
　

　　　　　　　　　　　　　　（选择磁盘类型）
２，选择“创建新虚拟磁盘（V）”选项，然后单击右下角“下一步”按钮。

　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　　（选择磁盘）
３，指定磁盘大小为20 GB，选择“将虚拟磁盘存储为单个文件（O）

　　　　　　　　　　　　　　（指定磁盘容量）
４，文件名不做修改，使用默认名称，然后单击右下角“完成”按钮。

　　　　　　　　　　　　　　（指定磁盘文件）
５，添加完磁盘后，重启虚拟机。重启过后，使用命令查看磁盘，命令如下：
　

／／可以看到存在一块名叫sdb的块设备，大小为20 GB。
[root@kvm ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk 
├─sda1            8:1    0  500M  0 part /boot
└─sda2            8:2    0 19.5G  0 part 
  ├─centos-root 253:0    0 17.5G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   20G  0 disk 
sr0              11:0    1    4G  0 rom

案例实施

　（1）创建物理卷

　在创建物理卷之前，需要对磁盘进行分区。首先使用fdisk命令对sdb进行分区操作，分出两个大小为5 GB的分区，命令如下：

[root@kvm ~]# fdisk /dev/sdb
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.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x132a9cad.
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x132a9cad
   Device Boot      Start         End      Blocks   Id  System
Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 
First sector (2048-41943039, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +5G
Partition 1 of type Linux and of size 5 GiB is set
Command (m for help): n
Partition type:
   p   primary (1 primary, 0 extended, 3 free)
   e   extended
Select (default p): p
Partition number (2-4, default 2): 
First sector (10487808-41943039, default 10487808): 
Using default value 10487808
Last sector, +sectors or +size{K,M,G} (10487808-41943039, default 41943039): +5G
Partition 2 of type Linux and of size 5 GiB is set
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x132a9cad
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    10487807     5242880   83  Linux
/dev/sdb2        10487808    20973567     5242880   83  Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@kvm ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk 
├─sda1            8:1    0  500M  0 part /boot
└─sda2            8:2    0 19.5G  0 part 
  ├─centos-root 253:0    0 17.5G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   20G  0 disk 
├─sdb1            8:17   0    5G  0 part 
└─sdb2            8:18   0    5G  0 part 
sr0              11:0    1    4G  0 rom

分完分区后，对这两个分区进行创建物理卷操作，命令如下：

[root@kvm ~]# pvcreate /dev/sdb1 /dev/sdb2
  Physical volume "/dev/sdb1" successfully created
  Physical volume "/dev/sdb2" successfully created
[root@kvm ~]# pvs
  PV         VG     Fmt  Attr PSize  PFree 
  /dev/sda2  centos lvm2 a--  19.51g 40.00m
  /dev/sdb1         lvm2 ---   5.00g  5.00g
  /dev/sdb2         lvm2 ---   5.00g  5.00g
[root@kvm ~]# pvdisplay 
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               19.51 GiB / not usable 3.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               10
  Allocated PE          4984
  PV UUID               O2nGDe-7kek-T7r5-FKTG-4PUm-RlAf-Ffra6L
  "/dev/sdb1" is a new physical volume of "5.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name               
  PV Size               5.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               BT2e34-cepq-nak7-3nB0-geDF-Ktoe-dOO5J7
  "/dev/sdb2" is a new physical volume of "5.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb2
  VG Name               
  PV Size               5.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               2iURqp-gTxm-rTcT-UlrY-cBqY-NFKQ-LC0XRq

（2）创建卷组

使用刚才创建好的两个物理卷，创建名为myvg的卷组，命令如下：

[root@kvm ~]# vgcreate myvg /dev/sdb[1-2]
  Volume group "myvg" successfully created    
[root@kvm ~]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree 
  centos   1   2   0 wz--n- 19.51g 40.00m
  myvg     2   0   0 wz--n-  9.99g  9.99g
[root@kvm ~]# vgdisplay
  --- Volume group ---
  VG Name               myvg
  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               UKeX39-nfMB-dX2Q-axko-SJoY-9e2Q-h7C4nq
  --- Volume group ---
  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               19.51 GiB
  PE Size               4.00 MiB
  Total PE              4994
  Alloc PE / Size       4984 / 19.47 GiB
  Free  PE / Size       10 / 40.00 MiB
  VG UUID               pQeQ2t-Ad5k-Gq1b-w8Ps-7Xof-SHAs-rnthvR
／／当多个物理卷组合成一个卷组后时，LVM会在所有的物理卷上做类似格式化的工作，将每个物理卷切成
一块一块的空间，这一块一块的空间就称为PE（Physical Extent），它的默认大小是4 MB。
由于受内核限制的原因，一个逻辑卷（Logic Volume）最多只能包含65536个PE（Physical Extent），
所以一个PE的大小就决定了逻辑卷的最大容量，4 MB的PE决定了单个逻辑卷最大容量为256 GB，若希望使
用大于256 Gb的逻辑卷，则创建卷组时需要指定更大的PE。
删除卷组，重新创建卷组，并指定PE大小为16 MB，命令如下：
[root@kvm ~]# vgremove myvg
  Volume group "myvg" successfully removed
[root@kvm ~]# vgcreate -s 16m myvg /dev/sdb[1-2]
  Volume group "myvg" successfully created
[root@kvm ~]# vgdisplay
  --- Volume group ---
  VG Name               myvg
  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               9.97 GiB　／／可以查看到现在myvg卷组的PE大小为16 MB。
  PE Size               16.00 MiB
  Total PE              638
  Alloc PE / Size       0 / 0   
  Free  PE / Size       638 / 9.97 GiB
  VG UUID               iRozOD-XE6z-dDIR-O7G0-psnE-i6bn-Cq7azu
  --- Volume group ---
  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               19.51 GiB
  PE Size               4.00 MiB
  Total PE              4994
  Alloc PE / Size       4984 / 19.47 GiB
  Free  PE / Size       10 / 40.00 MiB
  VG UUID               pQeQ2t-Ad5k-Gq1b-w8Ps-7Xof-SHAs-rnthvR
／／向卷组myvg中添加一个物理卷，在/dev/sdb上再分一个/dev/sdb3分区，把该分区加到卷组myvg中。命令如下： 
[root@kvm ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk 
├─sda1            8:1    0  500M  0 part /boot
└─sda2            8:2    0 19.5G  0 part 
  ├─centos-root 253:0    0 17.5G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   20G  0 disk 
├─sdb1            8:17   0    5G  0 part 
└─sdb2            8:18   0    5G  0 part 
sr0              11:0    1    4G  0 rom  
[root@kvm ~]# vgextend myvg /dev/sdb3
  Device /dev/sdb3 not found (or ignored by filtering).
  Unable to add physical volume '/dev/sdb3' to volume group 'myvg'.
[root@kvm ~]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree 
  centos   1   2   0 wz--n- 19.51g 40.00m
  myvg     2   0   0 wz--n-  9.97g  9.97g
[root@kvm ~]# vgdisplay myvg
  --- Volume group ---
  VG Name               myvg
  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               9.97 GiB
  PE Size               16.00 MiB
  Total PE              638
  Alloc PE / Size       0 / 0   
  Free  PE / Size       638 / 9.97 GiB
  VG UUID               iRozOD-XE6z-dDIR-O7G0-psnE-i6bn-Cq7azu

创建逻辑卷

创建逻辑卷，名称为mylv，大小为5 GB。

[root@kvm ~]# lvcreate -L +5G -n mylv myvg
  Logical volume "mylv" created.
[root@kvm ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao---- 17.47g                                                    
  swap centos -wi-ao----  2.00g                                                    
  mylv myvg   -wi-a-----  5.00g                                                    
[root@kvm ~]# lvscan
  ACTIVE            '/dev/myvg/mylv' [5.00 GiB] inherit
  ACTIVE            '/dev/centos/root' [17.47 GiB] inherit
  ACTIVE            '/dev/centos/swap' [2.00 GiB] inherit
[root@kvm ~]#  mkfs.ext4 /dev/mapper/myvg-mylv
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1310720 blocks
65536 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1342177280
40 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
    32768, 98304, 163840, 229376, 294912, 819200, 884736
Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done 
[root@kvm ~]# mount /dev/mapper/myvg-mylv /mnt/
[root@kvm ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   18G  1.2G   17G   7% /
devtmpfs                 479M     0  479M   0% /dev
tmpfs                    489M     0  489M   0% /dev/shm
tmpfs                    489M  6.7M  483M   2% /run
tmpfs                    489M     0  489M   0% /sys/fs/cgroup
/dev/sda1                497M  125M  373M  25% /boot
tmpfs                     98M     0   98M   0% /run/user/0
/dev/mapper/myvg-mylv    4.8G   20M  4.6G   1% /mnt

创建的LVM卷扩容至1 GB

[root@kvm ~]# lvextend -L +1G /dev/mapper/myvg-mylv
  Size of logical volume myvg/mylv changed from 5.00 GiB (320 extents) to 6.00 GiB (384 extents).
  Logical volume mylv successfully resized.
[root@kvm ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao---- 17.47g                                                    
  swap centos -wi-ao----  2.00g                                                    
  mylv myvg   -wi-ao----  6.00g                                                    
[root@kvm ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   18G  1.2G   17G   7% /
devtmpfs                 479M     0  479M   0% /dev
tmpfs                    489M     0  489M   0% /dev/shm
tmpfs                    489M  6.7M  483M   2% /run
tmpfs                    489M     0  489M   0% /sys/fs/cgroup
/dev/sda1                497M  125M  373M  25% /boot
tmpfs                     98M     0   98M   0% /run/user/0
/dev/mapper/myvg-mylv    4.8G   20M  4.6G   1% /mnt
[root@kvm ~]#  resize2fs /dev/mapper/myvg-mylv
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mapper/myvg-mylv is mounted on /mnt; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/mapper/myvg-mylv is now 1572864 blocks long.
[root@kvm ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   18G  1.2G   17G   7% /
devtmpfs                 479M     0  479M   0% /dev
tmpfs                    489M     0  489M   0% /dev/shm
tmpfs                    489M  6.7M  483M   2% /run
tmpfs                    489M     0  489M   0% /sys/fs/cgroup
/dev/sda1                497M  125M  373M  25% /boot
tmpfs                     98M     0   98M   0% /run/user/0
/dev/mapper/myvg-mylv    5.8G   20M  5.5G   1% /mnt