Linux LVM逻辑卷管理

使用Linux好久了,一定会意识到一个问题,某个分区容量不够用了,想要扩容怎么办?这里就涉及到LVM逻辑卷的管理了,可以动态调整Linux分区容量。


LVM 概述#

全称Logical Volume Manager,可以动态调整磁盘容量,提高磁盘管理灵活性。

在安装CentOS 7的过程中选择自动分区时,默认就是以LVM的方案安装的系统。

但是/boot分区必须独立出来,不能基于LVM创建。

PV 物理卷#

物理卷,Physical Volume,是LVM机制的基本存储设备,通常对应一个普通分区或是整个硬盘。

创建物理卷时,会在分区或磁盘头部创建一个用于记录LVM属性的保留区块,并把存储空间分割成默认大小为4MB的基本单元(Physical Extend,PE),从而构成物理卷。

普通分区先转换分区类型为8e;整块硬盘,可以将所有的空间划分为一个主分区再做调整。

VG 卷组#

卷组,Volume Group,是由一个或多个物理卷组成的一个整体。可以动态添加、移除物理卷,创建时可以指定PE大小。

LV 逻辑卷#

逻辑卷,Logical Volume,建立在卷组之上,与物理卷没有直接关系。格式化后,即可挂载使用。

三者关系#

Linux LVM逻辑卷管理

通过以上对三者的解释可以看出,建立LVM的过程。首先,将普通分区或整个硬盘创建为物理卷;然后,将一个或多个物理卷创建为卷组;最后,在卷组上分割不同的数据存储空间形成逻辑卷。有了逻辑卷,就可以格式化、挂载使用了。


LVM 管理#

LVM 常用命令#

功能 PV 管理命令 VG 管理命令 LV 管理命令
Scan(扫描) pvscan vgscan lvscan
Create(建立) pvcreate vgcreate lvcreate
Display(显示) pvdisplay vgdisplay lvdisplay
Remove(移除) pvremove vgremove lvremove
Extend(扩展) / vgextend lvextend
Reduce(减少) / vgreduce lvreduce

PV 管理#

pvsacn#

  • 扫描列出系统中所有的物理卷

-e:仅显示属于输出卷组的物理卷
-n:仅显示不属于任何卷组的物理卷

[root@localhost ~]# pvscan    PV /dev/sda2   VG centos          lvm2 [<19.00 GiB / 0    free]    PV /dev/sdb1                      lvm2 [<20.00 GiB]    PV /dev/sdc1                      lvm2 [<20.00 GiB]    Total: 3 [58.99 GiB] / in use: 1 [<19.00 GiB] / in no VG: 2 [<40.00 GiB]

pvcreate#

  • 将分区或整个硬盘转换成物理卷
[root@localhost ~]# pvcreate /dev/sd{b,c}1    Physical volume "/dev/sdb1" successfully created.    Physical volume "/dev/sdc1" successfully created.

pvdisplay#

  • 显示物理卷的详细信息
[root@localhost ~]# 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               E4eovQ-CgPo-OSDK-75MO-BfD8-pGsP-BUlqip      "/dev/sdb1" is a new physical volume of "<20.00 GiB"    --- NEW Physical volume ---    PV Name               /dev/sdb1    VG Name    PV Size               <20.00 GiB    Allocatable           NO    PE Size               0    Total PE              0    Free PE               0    Allocated PE          0    PV UUID               gR5mm3-f50o-XLTq-34GY-n6Iz-WXkQ-uMZAkJ      "/dev/sdc1" is a new physical volume of "<20.00 GiB"    --- NEW Physical volume ---    PV Name               /dev/sdc1    VG Name    PV Size               <20.00 GiB    Allocatable           NO    PE Size               0    Total PE              0    Free PE               0    Allocated PE          0    PV UUID               O2gKxa-ONts-kyXK-zZrO-3dDg-FhtI-V6GPy9

pvremove#

  • 删除指定的物理卷,还原成普通分区或磁盘

TIPS:只有不属于卷组的物理卷才可以删除还原。

[root@localhost ~]# pvremove /dev/sdd1    Labels on physical volume "/dev/sdd1" successfully wiped.

VG 管理#

vgscan#

  • 扫描系统中已建立的LVM卷组
[root@localhost ~]# vgscan    Reading volume groups from cache.    Found volume group "class" using metadata type lvm2    Found volume group "centos" using metadata type lvm2

vgcreate#

  • 将一个或多个物理卷创建为一个卷组

-l:卷组上允许创建的最大逻辑卷数
-p:卷组中允许添加的最大物理卷数
-s:卷组上的物理卷的PE大小

[root@localhost ~]# vgcreate class /dev/sd{b,c}1    Volume group "class" successfully created

vgdisplay#

  • 显示系统中各卷组的详细信息
[root@localhost ~]# vgdisplay    --- Volume group ---    VG Name               class    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               39.99 GiB    PE Size               4.00 MiB    Total PE              10238    Alloc PE / Size       0 / 0    Free  PE / Size       10238 / 39.99 GiB    VG UUID               ZtQvGX-YOdy-U8wj-mGQs-TT1e-1PBR-dBNKAG      --- 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               <19.00 GiB    PE Size               4.00 MiB    Total PE              4863    Alloc PE / Size       4863 / <19.00 GiB    Free  PE / Size       0 / 0    VG UUID               bLPJGb-SQQ3-KcUb-OSdo-qaMR-9hJE-MTkc7a

vgremove#

  • 删除指定的卷组

TIPS:卷组下面的逻辑卷没有被挂载使用,卷组删除时会一并删除下面的逻辑卷。

[root@localhost ~]# vgremove class    Volume group "class" successfully removed

vgextend#

  • 添加新的物理卷,动态扩展卷组的磁盘空间
[root@localhost ~]# vgextend class /dev/sdd1    Volume group "class" successfully extended

vgreduce#

  • 删除卷组中的物理卷,减少卷组容量,

-a:如果命令行中没有指定要删除的物理卷,则删除所有的空物理卷。(all)

TIPS:删除啊前确保对应的物理卷没有在使用,就是下面没有逻辑卷,否则删除不了。

[root@localhost ~]# vgreduce class /dev/sdd1    Removed "/dev/sdd1" from volume group "class"
[root@localhost ~]# vgreduce -a class    Physical volume "/dev/sdb1" still in use    Physical volume "/dev/sdc1" still in use    Removed "/dev/sdd1" from volume group "class"

LV 管理#

lvscan#

  • 扫描系统中已建立的LVM逻辑卷
[root@localhost ~]# lvscan    ACTIVE            '/dev/class/stu01' [25.00 GiB] inherit    ACTIVE            '/dev/class/stu02' [14.99 GiB] inherit    ACTIVE            '/dev/centos/swap' [2.00 GiB] inherit    ACTIVE            '/dev/centos/root' [<17.00 GiB] inherit

lvcreate#

  • 从指定的卷组中分割空间,创建新的逻辑卷

-L:指定逻辑卷的大小,单位为KMGT
-l:指定百分比创建,如50%vg卷组的一半空间、100%free所有剩下的。
-n:指定逻辑卷的名称

[root@localhost ~]# lvcreate -L 15G -n stu01 class    Logical volume "stu01" created.
[root@localhost ~]# lvcreate -l 100%free -n stu02 class    Logical volume "stu02" created.

lvdisplay#

  • 显示逻辑卷的详细信息
[root@localhost ~]# lvdisplay    --- Logical volume ---    LV Path                /dev/class/stu01    LV Name                stu01    VG Name                class    LV UUID                XUP7dq-IM9f-PdKk-XpDH-J1hx-kkuB-cOu3Qx    LV Write Access        read/write    LV Creation host, time localhost.localdomain, 2019-08-24 09:42:35 +0800    LV Status              available    # open                 0    LV Size                25.00 GiB    Current LE             6400    Segments               2    Allocation             inherit    Read ahead sectors     auto    - currently set to     8192    Block device           253:2      --- Logical volume ---    LV Path                /dev/class/stu02    LV Name                stu02    VG Name                class    LV UUID                P7iMC1-X0oT-6TCH-vLYj-HW2j-6QMu-rS7Jyp    LV Write Access        read/write    LV Creation host, time localhost.localdomain, 2019-08-24 09:59:30 +0800    LV Status              available    # open                 0    LV Size                14.99 GiB    Current LE             3838    Segments               1    Allocation             inherit    Read ahead sectors     auto    - currently set to     8192    Block device           253:3      --- Logical volume ---    LV Path                /dev/centos/swap    LV Name                swap    VG Name                centos    LV UUID                NXiaXT-T6yv-ktM2-plyS-j6Hg-hkvu-1JQ2eL    LV Write Access        read/write    LV Creation host, time localhost, 2019-08-16 17:12:19 +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      --- Logical volume ---    LV Path                /dev/centos/root    LV Name                root    VG Name                centos    LV UUID                7FnsfT-B8xi-3vgu-8N0k-nzNn-8Rra-eoE4iC    LV Write Access        read/write    LV Creation host, time localhost, 2019-08-16 17:12:19 +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

lvremove#

  • 删除指定的逻辑卷

TIPS:备份数据,解挂载,删除。

[root@localhost ~]# umount /mnt/stu02/  [root@localhost ~]# lvremove /dev/class/stu02

lvextend#

  • 动态扩展LVM逻辑卷的空间大小

-L:指定扩展逻辑卷的大小,单位为KMGT
-l:指定百分比扩建,如100%free所有剩下的。

[root@localhost ~]# lvextend -L +8G /dev/class/stu01  [root@localhost ~]# lvextend -L +8G /dev/class/stu02

TIPS:已挂载,使用在线调整大小,xfs使用xfs_growfsext4使用resize2fs

[root@localhost ~]# xfs_growfs /dev/class/stu01  [root@localhost ~]# resize2fs /dev/class/stu02

lvreduce#

  • 减少LVM逻辑卷的空间大小,

-L:指定逻辑卷的大小,单位为KMGT

TIPS:对于xfs文件系统,备份数据,解挂载,减少空间,强制格式化,重新挂载。需要注意xfs文件系统只能扩大,不能缩小,非要缩小的话,只有缩小后并强制格式化,但这么做数据就丢失了。

[root@localhost ~]# umount /mnt/stu01/  [root@localhost ~]# lvreduce -L -10G /dev/class/stu01  [root@localhost ~]# mkfs.xfs -f /dev/class/stu01  [root@localhost ~]# mount -a  [root@localhost ~]# df -hT

TIPS:对于ext4这类文件系统,备份数据,解挂载,e2fsck -f检查文件系统完整性,resize2fs设置文件系统大小,lvreduce设置逻辑卷大小,重新挂载。

[root@localhost ~]# umount /mnt/stu02/  [root@localhost ~]# e2fsck -f /dev/class/stu02  [root@localhost ~]# resize2fs /dev/class/stu02 10G  [root@localhost ~]# lvreduce -L 10G /dev/class/stu02  [root@localhost ~]# mount -a  [root@localhost ~]# df -hT

LVM 实验#

创建 LVM 逻辑卷#

1.添加两块20G的磁盘,重启机器,并对其进行分区,全部空间分为一个主分区,类型改为Linux LVM,ID为8e。分区过程省略,不清楚可参考上一篇博客。

[root@localhost ~]# fdisk -l /dev/sd{b,c} | grep -i "linux lvm"  /dev/sdb1            2048    41943039    20970496   8e  Linux LVM  /dev/sdc1            2048    41943039    20970496   8e  Linux LVM

2.将/dev/sdb1/dev/sdc1转换为物理卷。

[root@localhost ~]# pvcreate /dev/sd{b,c}1    Physical volume "/dev/sdb1" successfully created.    Physical volume "/dev/sdc1" successfully created.

3.创建名称为class的卷组,并将sdb1sdc1添加进卷组。

[root@localhost ~]# vgcreate class /dev/sd{b,c}1    Volume group "class" successfully created

4.划分大小为15G,名称为stu01的逻辑卷,然后再扩容10G;剩下的空间创建名称为stu02的逻辑卷。

[root@localhost ~]# lvcreate -L 15G -n stu01 class    Logical volume "stu01" created.  [root@localhost ~]# lvextend -L +10G /dev/class/stu01    Size of logical volume class/stu01 changed from 15.00 GiB (3840 extents) to 25.00 GiB (6400 extents).    Logical volume class/stu01 successfully resized.
[root@localhost ~]# lvcreate -l 100%free -n stu02 class    Logical volume "stu02" created.

5.格式化逻辑卷,stu01xfsstu02ext4,设置自动挂载,挂载后就可以使用了。

[root@localhost ~]# mkfs.xfs /dev/class/stu01  meta-data=/dev/class/stu01       isize=512    agcount=4, agsize=1638400 blks           =                       sectsz=512   attr=2, projid32bit=1           =                       crc=1        finobt=0, sparse=0  data     =                       bsize=4096   blocks=6553600, imaxpct=25           =                       sunit=0      swidth=0 blks  naming   =version 2              bsize=4096   ascii-ci=0 ftype=1  log      =internal log           bsize=4096   blocks=3200, version=2           =                       sectsz=512   sunit=0 blks, lazy-count=1  realtime =none                   extsz=4096   blocks=0, rtextents=0
[root@localhost ~]# mkfs.ext4 /dev/class/stu02  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  983040 inodes, 3930112 blocks  196505 blocks (5.00%) reserved for the super user  First data block=0  Maximum filesystem blocks=2151677952  120 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, 1605632, 2654208    Allocating group tables: done  Writing inode tables: done  Creating journal (32768 blocks): done  Writing superblocks and filesystem accounting information: done
[root@localhost ~]# mkdir /mnt/stu0{1,2}  [root@localhost ~]# vim /etc/fstab  //最后面添加下面两行内容  /dev/class/stu01        /mnt/stu01      xfs     defaults        0 0  /dev/class/stu02        /mnt/stu02      ext4    defaults        0 0
[root@localhost ~]# mount -a  [root@localhost ~]# df -hT  Filesystem              Type      Size  Used Avail Use% Mounted on  /dev/mapper/centos-root xfs        17G  927M   17G   6% /  devtmpfs                devtmpfs  901M     0  901M   0% /dev  tmpfs                   tmpfs     912M     0  912M   0% /dev/shm  tmpfs                   tmpfs     912M  8.7M  904M   1% /run  tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup  /dev/sda1               xfs      1014M  143M  872M  15% /boot  tmpfs                   tmpfs     183M     0  183M   0% /run/user/0  /dev/mapper/class-stu01 xfs        25G   33M   25G   1% /mnt/stu01  /dev/mapper/class-stu02 ext4       15G   41M   14G   1% /mnt/stu02

扩容 LVM 逻辑卷#

1.再添加一块20G的磁盘,重启机器,并对其进行分区,全部空间分为一个主分区,类型改为Linux LVM,ID为8e

[root@localhost ~]# fdisk -l /dev/sd{b..d} | grep -i "linux lvm"  /dev/sdb1            2048    41943039    20970496   8e  Linux LVM  /dev/sdc1            2048    41943039    20970496   8e  Linux LVM  /dev/sdd1            2048    41943039    20970496   8e  Linux LVM

2.将/dev/sdd1转换为物理卷。

[root@localhost ~]# pvcreate /dev/sdd1    Physical volume "/dev/sdd1" successfully created.

3.若是卷组剩余空间不够,就要先对class卷组进行扩容。

[root@localhost ~]# vgdisplay class    --- Volume group ---    VG Name               class    System ID    Format                lvm2    Metadata Areas        2    Metadata Sequence No  6    VG Access             read/write    VG Status             resizable    MAX LV                0    Cur LV                2    Open LV               2    Max PV                0    Cur PV                2    Act PV                2    VG Size               39.99 GiB    PE Size               4.00 MiB    Total PE              10238    Alloc PE / Size       10238 / 39.99 GiB    Free  PE / Size       0 / 0    VG UUID               iB1h9h-2uQa-rD7o-GBVK-pOCA-ek2c-TXieLr
[root@localhost ~]# vgextend class /dev/sdd1    Volume group "class" successfully extended
[root@localhost ~]# vgdisplay class    --- Volume group ---    VG Name               class    System ID    Format                lvm2    Metadata Areas        3    Metadata Sequence No  7    VG Access             read/write    VG Status             resizable    MAX LV                0    Cur LV                2    Open LV               2    Max PV                0    Cur PV                3    Act PV                3    VG Size               <59.99 GiB    PE Size               4.00 MiB    Total PE              15357    Alloc PE / Size       10238 / 39.99 GiB    Free  PE / Size       5119 / <20.00 GiB    VG UUID               iB1h9h-2uQa-rD7o-GBVK-pOCA-ek2c-TXieLr

4.对stu01stu02都扩容8G,分别使用xfs_growfsresize2fs在线调整大小。

[root@localhost ~]# lvextend -L +8G /dev/class/stu01    Size of logical volume class/stu01 changed from 25.00 GiB (6400 extents) to 33.00 GiB (8448 extents).    Logical volume class/stu01 successfully resized.
[root@localhost ~]# lvextend -L +8G /dev/class/stu02    Size of logical volume class/stu02 changed from 14.99 GiB (3838 extents) to 22.99 GiB (5886 extents).    Logical volume class/stu02 successfully resized.
[root@localhost ~]# xfs_growfs /dev/class/stu01  meta-data=/dev/mapper/class-stu01 isize=512    agcount=4, agsize=1638400 blks           =                       sectsz=512   attr=2, projid32bit=1           =                       crc=1        finobt=0 spinodes=0  data     =                       bsize=4096   blocks=6553600, imaxpct=25           =                       sunit=0      swidth=0 blks  naming   =version 2              bsize=4096   ascii-ci=0 ftype=1  log      =internal               bsize=4096   blocks=3200, version=2           =                       sectsz=512   sunit=0 blks, lazy-count=1  realtime =none                   extsz=4096   blocks=0, rtextents=0  data blocks changed from 6553600 to 8650752
[root@localhost ~]# resize2fs /dev/class/stu02  resize2fs 1.42.9 (28-Dec-2013)  Filesystem at /dev/class/stu02 is mounted on /mnt/stu02; on-line resizing required  old_desc_blocks = 2, new_desc_blocks = 3  The filesystem on /dev/class/stu02 is now 6027264 blocks long.
[root@localhost ~]# df -hT  Filesystem              Type      Size  Used Avail Use% Mounted on  /dev/mapper/centos-root xfs        17G  927M   17G   6% /  devtmpfs                devtmpfs  901M     0  901M   0% /dev  tmpfs                   tmpfs     912M     0  912M   0% /dev/shm  tmpfs                   tmpfs     912M  8.7M  903M   1% /run  tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup  /dev/sda1               xfs      1014M  143M  872M  15% /boot  /dev/mapper/class-stu01 xfs        33G   33M   33G   1% /mnt/stu01  /dev/mapper/class-stu02 ext4       23G   44M   22G   1% /mnt/stu02  tmpfs                   tmpfs     183M     0  183M   0% /run/user/0

收缩 LVM 逻辑卷#

关于收缩 LVM 逻辑卷,可以参考上面的命令lvreduce。这会涉及到数据安全性问题,谨慎使用。


总结#

内容不多,但是还要实际操作才能了解。就是三步走,创建物理卷,创建卷组,创建逻辑卷,然后格式化并挂载使用。扩容的话,没有挂载使用,就正常扩,然后格式化挂载,已经挂载使用了,扩容后在线调整生效。还有下一篇关于磁盘配额。

Linux LVM逻辑卷管理

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