七、逻辑卷管理器
一、 lvm
一、LVM（logical volume manager 逻辑卷管理器）：内核支持的功能 以分区为单位
1.）企业生产当中遇到的问题：
1.分好区之后，某个业务不断扩张，某个分区磁盘空间不够啦。但是 其他分区还有剩余空间，如何做内部调整
2.整个磁盘空间都不够用了，难道我要买一块新的硬盘，重新安装操作系统，然后把数据 COPY 到新的硬盘上边吗？
3.多个磁盘上边有剩余空间，如何整合剩余空间成为一块新的磁盘？
4.能不能在磁盘管理上扩展性更加灵活？
IBM，Linux kernel 2.4 版本的时候引入到 Linux 当中。目前使用的是 LVM V2 版本
2.）举例说明什么是 LVM：
逻辑卷管理器的优点：
1.分区动态扩充，业务不中断
2.可以给分区拍快照
3.存储的基础
4.不需要安装额外的软件包 是内核所支持的功能！！！！
3.）创建逻辑卷管理器的概念
pv：物理卷，物理的分区，逻辑卷管理器物理存储设备。
vg：卷组，虚拟磁盘。一个或若干物理卷的集合
lv：逻辑卷，一个模拟出来的分区 在使用的时候 和正常的分区无差别--------创建文件系统挂载、使用
可以动态调整分区创建快照
4.）使用逻辑卷的过程：
1.创建物理卷-->2.创建卷组-->3.创建逻辑卷-->4.创建文件系统-->5.挂载使用
5.）LVM 中的基本命令
二、 实验
[root@localhost ~]# fdisk /dev/sdc
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 0xfb374980.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-10485759, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-10485759, default 10485759): +512M
Partition 1 of type Linux and of size 512 MiB is set
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p):
Using default response p
Partition number (2-4, default 2):
First sector (1050624-10485759, default 1050624):
Using default value 1050624
Last sector, +sectors or +size{K,M,G} (1050624-10485759, default 10485759): +512M
Partition 2 of type Linux and of size 512 MiB is set
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 (2099200-10485759, default 2099200):
Using default value 2099200
Last sector, +sectors or +size{K,M,G} (2099200-10485759, default 10485759): +512M
Partition 3 of type Linux and of size 512 MiB is set
Command (m for help): p
Disk /dev/sdc: 5368 MB, 5368709120 bytes, 10485760 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: 0xfb374980
Device Boot Start End Blocks Id System
/dev/sdc1 2048 1050623 524288 83 Linux
/dev/sdc2 1050624 2099199 524288 83 Linux
/dev/sdc3 2099200 3147775 524288 83 Linux
Command (m for help): t
Partition number (1-3, default 3):
Hex code (type L to list all codes): l
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sdc: 5368 MB, 5368709120 bytes, 10485760 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: 0xfb374980
Device Boot Start End Blocks Id System
/dev/sdc1 2048 1050623 524288 83 Linux
/dev/sdc2 1050624 2099199 524288 83 Linux
/dev/sdc3 2099200 3147775 524288 8e Linux LVM
Command (m for help): t
Partition number (1-3, default 3): 2
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): t
Partition number (1-3, default 3): 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sdc: 5368 MB, 5368709120 bytes, 10485760 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: 0xfb374980
Device Boot Start End Blocks Id System
/dev/sdc1 2048 1050623 524288 8e Linux LVM
/dev/sdc2 1050624 2099199 524288 8e Linux LVM
/dev/sdc3 2099200 3147775 524288 8e Linux LVM
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# partprobe /dev/sdc
[root@localhost ~]# pvcreate /dev/sdc[1-3] //连续创建物理卷
Physical volume "/dev/sdc1" successfully created.
Physical volume "/dev/sdc2" successfully created.
Physical volume "/dev/sdc3" successfully created.
[root@localhost ~]# vgcreate mainvg /dev/sdc[1-3] //创建卷组名称为 mainvg
Volume group "mainvg" successfully created
[root@localhost ~]# pvs //扫描系统中的物理卷
PV VG Fmt Attr PSize PFree
/dev/sdc1 mainvg lvm2 a-- 508.00m 508.00m
/dev/sdc2 mainvg lvm2 a-- 508.00m 508.00m
/dev/sdc3 mainvg lvm2 a-- 508.00m 508.00m
[root@localhost ~]# vgs //检测系统中的卷组
VG #PV #LV #SN Attr VSize VFree
mainvg 3 0 0 wz--n- 1.49g 1.49g
[root@localhost ~]# lvcreate -n 1stlv -L 400M mainvg //-n 指定名字 -L 指定大小 卷组名称 分配逻辑卷
Logical volume "1stlv" created.
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdc1 mainvg lvm2 a-- 508.00m 108.00m
/dev/sdc2 mainvg lvm2 a-- 508.00m 508.00m
/dev/sdc3 mainvg lvm2 a-- 508.00m 508.00m
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
mainvg 3 1 0 wz--n- 1.49g 1.10g
逻辑卷的设备标识符
[root@localhost ~]# ll /dev/mainvg/1stlv
lrwxrwxrwx. 1 root root 7 Jan 8 02:52 /dev/mainvg/1stlv -> ../dm-0
[root@localhost ~]# ll /dev/mapper/mainvg-1stlv
lrwxrwxrwx. 1 root root 7 Jan 8 02:52 /dev/mapper/mainvg-1stlv -> ../dm-0
[root@localhost ~]# mkfs.ext4 /dev/mainvg/1stlv
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
102400 inodes, 409600 blocks
20480 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=34078720
50 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
[root@localhost ~]# cd /tmp/
[root@localhost tmp]# mkdir wu
[root@localhost tmp]# echo "/dev/mainvg/1stlv /tmp/wu ext4 defaults 0 0" >>/etc/fstab
[root@localhost tmp]# mount -a
[root@localhost tmp]# mount |grep /tmp/wu
/dev/mapper/mainvg-1stlv on /tmp/wu type ext4 (rw,relatime,seclabel,data=ordered)
[root@localhost tmp]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/sda6 18G 4.5G 14G 25% /
devtmpfs 474M 0 474M 0% /dev
tmpfs 489M 144K 489M 1% /dev/shm
tmpfs 489M 7.2M 482M 2% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sda2 509M 26M 483M 6% /home
/dev/sda1 509M 162M 347M 32% /boot
tmpfs 98M 12K 98M 1% /run/user/0
/dev/mapper/mainvg-1stlv 380M 2.3M 354M 1% /tmp/wu
逻辑卷的设备标识符
1、/dev/卷组名/逻辑卷名
2、/dev/mapper/卷组名-逻辑卷名
[root@localhost tmp]# lvcreate -L 500M -n 2edlv mainvg //创建逻辑卷
Logical volume "2edlv" created.
[root@localhost tmp]# mkfs.xfs /dev/mainvg/2edlv //为逻辑卷创建一个 xfs 系统
[root@localhost tmp]# mkdir /tmp/2edlv
[root@localhost tmp]# echo "/dev/mapper/mainvg-2edlv /tmp/2edlv xfs defaults 0 0" >> /etc/fstab
[root@localhost tmp]# mount -a
[root@localhost tmp]# vgs
VG #PV #LV #SN Attr VSize VFree
mainvg 3 2 0 wz--n- 1.49g 624.00m
[root@localhost tmp]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdc1 mainvg lvm2 a-- 508.00m 108.00m
/dev/sdc2 mainvg lvm2 a-- 508.00m 8.00m
/dev/sdc3 mainvg lvm2 a-- 508.00m 508.00m
调整 lvm 及包含文件系统
1.ext4 文件系统 lvm 的扩大
（1）扩大 LV（2）扩大文件系统
[root@localhost tmp]# lvresize -L 520M /dev/mainvg/1stlv // 扩大 LV
Size of logical volume mainvg/1stlv changed from 400.00 MiB (100 extents) to 520.00 MiB (130 extents).
Logical volume mainvg/1stlv successfully resized.
[root@localhost tmp]# lvresize -L +140M /dev/mainvg/1stlv // 扩大 LV
Size of logical volume mainvg/1stlv changed from 400.00 MiB (100 extents) to 520.00 MiB (130 extents).
Logical volume mainvg/1stlv successfully resized.
以上两种方式相同
[root@localhost tmp]# resize2fs /dev/mainvg/1stlv //扩大文件系统
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mainvg/1stlv is mounted on /tmp/wu; on-line resizing required
old_desc_blocks = 4, new_desc_blocks = 5
The filesystem on /dev/mainvg/1stlv is now 532480 blocks long.
[root@localhost tmp]# df -lh | grep 1st
/dev/mapper/mainvg-1stlv 496M 2.3M 465M 1% /tmp/wu
2.包含 ext 文件系统的 lv 缩小
（1）卸载文件系统（2）缩小文件系统（e2fsck）（3）缩小逻辑卷
[root@localhost tmp]# umount /tmp/wu/ //卸载文件系统
[root@localhost tmp]# e2fsck -f /dev/mainvg/1stlv // 检查分区
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/mainvg/1stlv: 11/133120 files (0.0% non-contiguous), 27326/532480 blocks
[root@localhost tmp]# resize2fs /dev/mainvg/1stlv 100M //缩小文件系统
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/mainvg/1stlv to 102400 (1k) blocks.
The filesystem on /dev/mainvg/1stlv is now 102400 blocks long.
[root@localhost tmp]# lvresize /dev/mainvg/1stlv -L 120M //缩小逻辑卷
WARNING: Reducing active logical volume to 120.00 MiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce mainvg/1stlv? [y/n]: y
Size of logical volume mainvg/1stlv changed from 400.00 MiB (100 extents) to 120.00 MiB (30 extents).
Logical volume mainvg/1stlv successfully resized.
[root@localhost tmp]# mount -a
包含 ext 文件系统的调整：在线放大、离线缩小、缩小的时候一旦顺序颠倒，文件系统将会损坏，文件将会丢失，
不可恢复！在实际生产当中，几乎不缩小 LV
调整包含 xfs 文件系统的 lv
（1）扩大 LV（2）扩大文件系统
[root@localhost tmp]# lvresize /dev/mainvg/2edlv -L 800M //扩大 lv
Size of logical volume mainvg/2edlv changed from 500.00 MiB (125 extents) to 800.00 MiB (200 extents).
Logical volume mainvg/2edlv successfully resized.
[root@localhost tmp]# xfs_growfs /dev/mainvg/2edlv //扩大 xfs 的文件系统
[root@localhost tmp]# df -lh | grep 2ed
/dev/mapper/mainvg-2edlv 797M 26M 772M 4% /tmp/2edlv
xfs 系统无法缩小
卷组 vg 的调整
VG 的扩充：通过 pv 的方式扩充物理卷
[root@localhost tmp]# pvcreate /dev/sdb1
WARNING: xfs signature detected on /dev/sdb1 at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/sdb1.
Physical volume "/dev/sdb1" successfully created.
[root@localhost tmp]# vgextend mainvg /dev/sdb1
Volume group "mainvg" successfully extended
[root@localhost tmp]# vgreduce mainvg /dev/sdb1 //删除没被使用的物理卷
Removed "/dev/sdb1" from volume group "mainvg"
通过向卷组添加物理卷 vgextend 的方式扩大卷组也可以吧没有使用的物理卷通过 vgreduce 命令剔除出去
三、 pv 的迁移
[root@localhost tmp]# vgextend mainvg /dev/sdb1 //把需要替换的其他物理设备添加到物理卷中
Volume group "mainvg" successfully extended
[root@localhost tmp]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 mainvg lvm2 a-- 2.00g 2.00g
/dev/sdc1 mainvg lvm2 a-- 508.00m 8.00m
/dev/sdc2 mainvg lvm2 a-- 508.00m 0
/dev/sdc3 mainvg lvm2 a-- 508.00m 216.00m
[root@localhost tmp]# pvmove /dev/sdc2 /dev/sdb1 //把 sdc2 数据迁移到 sdb1 上
/dev/sdc2: Moved: 2.36%
/dev/sdc2: Moved: 100.00%
[root@localhost tmp]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 mainvg lvm2 a-- 2.00g 1.50g
/dev/sdc1 mainvg lvm2 a-- 508.00m 8.00m
/dev/sdc2 mainvg lvm2 a-- 508.00m 508.00m
/dev/sdc3 mainvg lvm2 a-- 508.00m 216.00m
[root@localhost tmp]# vgreduce mainvg /dev/sdc2 //把 sdc2 移除卷组中
Removed "/dev/sdc2" from volume group "mainvg"
[root@localhost tmp]# pvremove /dev/sdc2 //把删除物理卷
Labels on physical volume "/dev/sdc2" successfully wiped.
[root@localhost tmp]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 mainvg lvm2 a-- 2.00g 1.50g
/dev/sdc1 mainvg lvm2 a-- 508.00m 8.00m
/dev/sdc3 mainvg lvm2 a-- 508.00m 216.00m
四、 卷组的迁移
单位：卷组
1.业务离线
[root@localhost tmp]# umount /dev/mainvg/1stlv
[root@localhost tmp]# umount /dev/mainvg/2edlv
2.去激活业务（卷组）
[root@localhost tmp]# vgchange -a n mainvg
0 logical volume(s) in volume group "mainvg" now active
3.导出设备（卷组）
[root@localhost tmp]# vgexport mainvg
Volume group "mainvg" successfully exported
4.把硬盘物理卸载掉 在另外一台电脑上关机插入这些硬盘 开机
在另一台机器上
1.做磁盘检索
[root@localhost tmp]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 mainvg lvm2 ax- 2.00g 1.50g
/dev/sdc1 mainvg lvm2 ax- 508.00m 8.00m
/dev/sdc3 mainvg lvm2 ax- 508.00m 216.00m
2.导入卷组
[root@localhost tmp]# vgimport mainvg
Volume group "mainvg" successfully imported
3.激活卷组
[root@localhost tmp]# vgchange -a y mainvg
2 logical volume(s) in volume group "mainvg" now active
4.挂载正常使用
作业：以上练习外删除 pv/vg/lv 各种 display【查看设备详细信息】
[root@localhost tmp]# umount /dev/mainvg/a
[root@localhost tmp]# umount /dev/mainvg/b
umount: /dev/mainvg/b: not mounted
[root@localhost tmp]# lvremove /dev/mainvg/a
Do you really want to remove active logical volume mainvg/a? [y/n]: y
Logical volume "a" successfully removed
[root@localhost tmp]# vgremove mainvg
Volume group "mainvg" successfully removed
[root@localhost tmp]# pvremove /dev/sdc1
Labels on physical volume "/dev/sdc1" successfully wiped.
[root@localhost tmp]# pvremove /dev/sdc2
Labels on physical volume "/dev/sdc2" successfully wiped.
[root@localhost tmp]# pvremove /dev/sdc3
Labels on physical volume "/dev/sdc3" successfully wiped.
