1、逻辑卷简要说明
将设备指定为物理卷
用一个或者多个物理卷来创建一个卷组
物理卷是用固定大小的物理区域（Physical Extent，PE）来定义的
在物理卷上创建的逻辑卷是由物理区域（PE）组成
可以在逻辑卷上创建文件系统
Paste_Image.png
2、创建逻辑卷
[root@centos7 ~]#pvcreate /dev/sdb /dev/sdc1 ---创建物理卷
Physical volume "/dev/sdb" successfully created.
Physical volume "/dev/sdc1" successfully created.
[root@centos7 ~]#pvs ---查看
PV VG Fmt Attr PSize PFree
/dev/sdb lvm2 --- 20.00g 20.00g
/dev/sdc1 lvm2 --- 15.00g 15.00g
[root@centos7 ~]#pvdisplay ---详细查看
"/dev/sdb" is a new physical volume of "20.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb
VG Name
PV Size 20.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 72dJR7-GCfL-GOHH-Tg9a-IIbl-EgTD-YLrRGz
"/dev/sdc1" is a new physical volume of "15.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc1
VG Name
PV Size 15.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID j8i7QQ-sSR2-bsJn-UlJj-a1jY-Ubum-KRYgWx
[root@centos7 ~]#vgcreate vg0 /dev/sd{b,c1} ----创建卷组，可以用-s选项指定PE的大小
Volume group "vg0" successfully created
[root@centos7 ~]#pvdisplay ---创建完卷组后再来看物理卷
--- Physical volume ---
PV Name /dev/sdb
VG Name vg0 ---卷组名
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB ---PE大小
Total PE 5119 ---PE个数逻辑卷，分逻辑卷时是把PE分给
Free PE 5119
Allocated PE 0
PV UUID 72dJR7-GCfL-GOHH-Tg9a-IIbl-EgTD-YLrRGz
--- Physical volume ---
PV Name /dev/sdc1
VG Name vg0
PV Size 15.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 3839
Free PE 3839
Allocated PE 0
PV UUID j8i7QQ-sSR2-bsJn-UlJj-a1jY-Ubum-KRYgWx
[root@centos7 ~]#vgs ---查看卷组
VG #PV #LV #SN Attr VSize VFree
vg0 2 0 0 wz--n- 34.99g 34.99g
[root@centos7 ~]#vgdisplay ---详细查看
--- Volume group ---
VG Name vg0
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 34.99 GiB
PE Size 4.00 MiB
Total PE 8958
Alloc PE / Size 0 / 0
Free PE / Size 8958 / 34.99 GiB
VG UUID HMIGkc-kO3K-sd6j-YuPc-i6ez-IOqY-KIReKJ
[root@centos7 ~]#lvcreate -n lv0 -L 15G vg0 ---创建逻辑卷
Logical volume "lv0" created.
[root@centos7 ~]#lvs ---查看逻辑卷
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv0 vg0 -wi-a----- 15.00g
[root@centos7 ~]#lvdisplay ---详细查看
--- Logical volume ---
LV Path /dev/vg0/lv0
LV Name lv0
VG Name vg0
LV UUID HH3DXN-bMUd-ebeu-89Vs-ifnw-XYE5-aEBotX
LV Write Access read/write
LV Creation host, time centos7.magedu.com, 2017-08-12 11:49:32 +0800
LV Status available
# open 0
LV Size 15.00 GiB
Current LE 3840
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@centos7 ~]#ll /dev/vg0/lv0 ---可以看到逻辑卷的设备名为一个软连接
lrwxrwxrwx. 1 root root 7 Aug 12 11:49 /dev/vg0/lv0 -> ../dm-0
[root@centos7 ~]#lvcreate -n lv1 -L 10G vg0 ---再创建一个逻辑卷
Logical volume "lv1" created.
[root@centos7 ~]#lvdisplay ---此时有两个逻辑卷
--- Logical volume ---
LV Path /dev/vg0/lv0
LV Name lv0
VG Name vg0
LV UUID HH3DXN-bMUd-ebeu-89Vs-ifnw-XYE5-aEBotX
LV Write Access read/write
LV Creation host, time centos7.magedu.com, 2017-08-12 11:49:32 +0800
LV Status available
# open 0
LV Size 15.00 GiB
Current LE 3840
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/vg0/lv1
LV Name lv1
VG Name vg0
LV UUID RAIOfB-sJ1U-0wGj-FPjn-53SZ-rBeE-AvsvBp
LV Write Access read/write
LV Creation host, time centos7.magedu.com, 2017-08-12 12:00:14 +0800
LV Status available
# open 0
LV Size 10.00 GiB
Current LE 2560
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
[root@centos7 ~]#mkfs.ext4 /dev/vg0/lv0 ---创建文件系统
[root@centos7 ~]#mkdir /mnt/lv0
[root@centos7 ~]#mount /dev/vg0/lv0 /mnt/lv0/ ---挂载
[root@centos7 ~]#df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 52403200 15338660 37064540 30% /
devtmpfs 485268 0 485268 0% /dev
tmpfs 499980 88 499892 1% /dev/shm
tmpfs 499980 13544 486436 3% /run
tmpfs 499980 0 499980 0% /sys/fs/cgroup
/dev/sda3 52403200 540228 51862972 2% /app
/dev/sda1 1038336 172284 866052 17% /boot
tmpfs 100000 16 99984 1% /run/user/0
/dev/sr0 8086368 8086368 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0 15350728 40984 14506928 1% /mnt/lv0
总结：创建逻辑卷的过程是在磁盘或者分区上先创建物理卷，如果是分区，创建分区时要指定id号为LVM，之后再创建卷组，通过卷组再创建逻辑卷，因为逻辑卷是通过卷组创建的，所以卷组中创建了PE
，默认PE大小为4MiB，用它来指定逻辑卷的最小块的单位，在创建卷组时可以通过-s来指定PE的大小来指定逻辑卷中块的大小，在没有创建卷组时物理卷中的PE是没有的，创建之后物理卷中才能看到。
3、扩展逻辑卷
[root@centos7 app]#vgdisplay ---首先要看卷组里是否有剩余空间
--- Volume group ---
VG Name vg0
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 34.99 GiB
PE Size 4.00 MiB
Total PE 8958
Alloc PE / Size 6400 / 25.00 GiB
Free PE / Size 2558 / 9.99 GiB ----卷组剩下空间
VG UUID HMIGkc-kO3K-sd6j-YuPc-i6ez-IOqY-KIReKJ
①没有剩余空间
[root@centos7 app]#pvcreate /dev/sdc2
WARNING: dos signature detected on /dev/sdc2 at offset 510. Wipe it? [y/n]: y
Wiping dos signature on /dev/sdc2.
Physical volume "/dev/sdc2" successfully created. ---创建物理卷
[root@centos7 app]#vgextend vg0 /dev/sdc2 ---扩展卷组，将物理卷加到卷组里
Volume group "vg0" successfully extended
[root@centos7 app]#vgdisplay
--- Volume group ---
VG Name vg0
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 1
Max PV 0
Cur PV 3
Act PV 3
VG Size 54.99 GiB
PE Size 4.00 MiB
Total PE 14077
Alloc PE / Size 6400 / 25.00 GiB
Free PE / Size 7677 / 29.99 GiB ---卷组的空间扩大
VG UUID HMIGkc-kO3K-sd6j-YuPc-i6ez-IOqY-KIReKJ
[root@centos7 app]#lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv0 vg0 -wi-ao---- 15.00g
lv1 vg0 -wi-a----- 10.00g
[root@centos7 app]#lvextend -L 20g /dev/vg0/lv0 ---扩展逻辑卷到20G
Size of logical volume vg0/lv0 changed from 15.00 GiB (3840 extents) to 20.00 GiB (5120 extents).
Logical volume vg0/lv0 successfully resized.
[root@centos7 app]#lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv0 vg0 -wi-ao---- 20.00g
lv1 vg0 -wi-a----- 10.00g
[root@centos7 app]#df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 50G 15G 36G 30% /
devtmpfs 474M 0 474M 0% /dev
tmpfs 489M 88K 489M 1% /dev/shm
tmpfs 489M 14M 476M 3% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sda3 50G 1.1G 49G 3% /app
/dev/sda1 1014M 169M 846M 17% /boot
tmpfs 98M 16K 98M 1% /run/user/0
/dev/sr0 7.8G 7.8G 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0 15G 541M 14G 4% /mnt/lv0 ---此时文件系统显示的大小还是15G，说明文件系统没有同步
如果是xfs文件系统：xfs_growfs /mnt/lv0
[root@centos7 app]#resize2fs /dev/vg0/lv0 20G ---让文件系统同步
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/vg0/lv0 is mounted on /mnt/lv0; on-line resizing required
old_desc_blocks = 2, new_desc_blocks = 3
The filesystem on /dev/vg0/lv0 is now 5242880 blocks long.
[root@centos7 app]#df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda2 xfs 50G 15G 36G 30% /
devtmpfs devtmpfs 474M 0 474M 0% /dev
tmpfs tmpfs 489M 88K 489M 1% /dev/shm
tmpfs tmpfs 489M 14M 476M 3% /run
tmpfs tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sda3 xfs 50G 1.1G 49G 3% /app
/dev/sda1 xfs 1014M 169M 846M 17% /boot
tmpfs tmpfs 98M 16K 98M 1% /run/user/0
/dev/sr0 iso9660 7.8G 7.8G 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0 ext4 20G 544M 19G 3% /mnt/lv0 ---已经同步
②有剩余空间
[root@centos7 app]#mkfs.xfs /dev/vg0/lv1 ---对逻辑卷lv1创建文件系统
[root@centos7 app]#mount /dev/vg0/lv1 /mnt/lv1 ---挂载
[root@centos7 app]#df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 50G 15G 36G 30% /
devtmpfs 474M 0 474M 0% /dev
tmpfs 489M 88K 489M 1% /dev/shm
tmpfs 489M 14M 476M 3% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sda3 50G 1.1G 49G 3% /app
/dev/sda1 1014M 169M 846M 17% /boot
tmpfs 98M 16K 98M 1% /run/user/0
/dev/sr0 7.8G 7.8G 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0 20G 544M 19G 3% /mnt/lv0
/dev/mapper/vg0-lv1 10G 33M 10G 1% /mnt/lv1
[root@centos7 app]#lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv0 vg0 -wi-ao---- 20.00g
lv1 vg0 -wi-ao---- 10.00g
[root@centos7 app]#lvextend -r -L +5G /dev/vg0/lv1 ---将lv1逻辑卷增加5G，-r选项可以实现自动同步文件系统。
Size of logical volume vg0/lv1 changed from 10.00 GiB (2560 extents) to 15.00 GiB (3840 extents).
Logical volume vg0/lv1 successfully resized.
meta-data=/dev/mapper/vg0-lv1 isize=512 agcount=4, agsize=655360 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=2621440, 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 2621440 to 3932160
[root@centos7 app]#lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv0 vg0 -wi-ao---- 20.00g
lv1 vg0 -wi-ao---- 15.00g ---已增加
[root@centos7 app]#df -h ---我们看到已经自动同步文件系统
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 50G 15G 36G 30% /
devtmpfs 474M 0 474M 0% /dev
tmpfs 489M 88K 489M 1% /dev/shm
tmpfs 489M 14M 476M 3% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sda3 50G 1.1G 49G 3% /app
/dev/sda1 1014M 169M 846M 17% /boot
tmpfs 98M 16K 98M 1% /run/user/0
/dev/sr0 7.8G 7.8G 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0 20G 544M 19G 3% /mnt/lv0
/dev/mapper/vg0-lv1 15G 33M 15G 1% /mnt/lv1
4、缩减逻辑卷
只有逻辑卷是ext4文件系统的才能缩减逻辑卷,生产中一般不会缩减逻辑卷，有可能会破坏数据
[root@centos7 lv0]#df -T --这里我们缩减lv0逻辑卷
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/sda2 xfs 52403200 15338912 37064288 30% /
devtmpfs devtmpfs 485268 0 485268 0% /dev
tmpfs tmpfs 499980 88 499892 1% /dev/shm
tmpfs tmpfs 499980 13548 486432 3% /run
tmpfs tmpfs 499980 0 499980 0% /sys/fs/cgroup
/dev/sda3 xfs 52403200 1052228 51350972 3% /app
/dev/sda1 xfs 1038336 172284 866052 17% /boot
tmpfs tmpfs 100000 16 99984 1% /run/user/0
/dev/sr0 iso9660 8086368 8086368 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0 ext4 20511312 557040 18931260 3% /mnt/lv0
/dev/mapper/vg0-lv1 xfs 15718400 71272 15647128 1% /mnt/lv1
[root@centos7 lv0]#umount /mnt/lv0 ---第一步取消挂载
[root@centos7 ~]#fsck -f /dev/vg0/lv0 ---第二步检查文件系统
fsck from util-linux 2.23.2
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/mapper/vg0-lv0: 12/1310720 files (0.0% non-contiguous), 126323/5242880 blocks
[root@centos7 ~]#resize2fs /dev/vg0/lv0 18G ---第三步缩减文件系统到18G
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg0/lv0 to 4718592 (4k) blocks.
The filesystem on /dev/vg0/lv0 is now 4718592 blocks long.
[root@centos7 ~]#lvreduce -L 18G /dev/vg0/lv0 ---第四步缩减逻辑卷到18G
WARNING: Reducing active logical volume to 18.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce vg0/lv0? [y/n]: y
Size of logical volume vg0/lv0 changed from 20.00 GiB (5120 extents) to 18.00 GiB (4608 extents).
Logical volume vg0/lv0 successfully resized.
[root@centos7 ~]#lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv0 vg0 -wi-ao---- 18.00g ---已经缩减
lv1 vg0 -wi-ao---- 15.00g
[root@centos7 ~]#mount -a
[root@centos7 ~]#df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda2 xfs 50G 15G 36G 30% /
devtmpfs devtmpfs 474M 0 474M 0% /dev
tmpfs tmpfs 489M 88K 489M 1% /dev/shm
tmpfs tmpfs 489M 20M 469M 4% /run
tmpfs tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sda3 xfs 50G 1.1G 49G 3% /app
/dev/sda1 xfs 1014M 169M 846M 17% /boot
tmpfs tmpfs 98M 16K 98M 1% /run/user/0
/dev/sr0 iso9660 7.8G 7.8G 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv1 xfs 15G 70M 15G 1% /mnt/lv1
/dev/mapper/vg0-lv0 ext4 18G 45M 17G 1% /mnt/lv0
总结：缩减逻辑卷的过程中是先取消挂载，这一步很重要，不要忘记，然后检查文件系统，缩减文件系统，缩减逻辑卷，要按照这个过程一步步的来。
5、迁移卷组
[root@centos6 ~]#umount /mnt/lv0/ ---第一步取消挂载
[root@centos6 ~]#df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 50264772 4786024 42918748 11% /
tmpfs 502056 76 501980 1% /dev/shm
/dev/sda3 40185208 561020 37576188 2% /app
/dev/sda1 991512 34904 905408 4% /boot
/dev/sr0 6049912 6049912 0 100% /media/CDROM
[root@centos6 ~]#vgrename vg0 newvg0 ---第二步为了和其他卷组的名字冲突，重新定义卷组和逻辑卷的名字
Volume group "vg0" successfully renamed to "newvg0"
[root@centos6 ~]#lvrename /dev/newvg0/lv0 newlv0 ---逻辑卷的名字改不改都可以，卷组的名字变了，逻辑卷的名字也跟着变了
Renamed "lv0" to "newlv0" in volume group "newvg0"
[root@centos6 ~]#vgchange -an newvg0 ---第三步把卷组设为非活动状态
0 logical volume(s) in volume group "newvg0" now active
[root@centos6 ~]#lvdisplay
--- Logical volume ---
LV Path /dev/newvg0/newlv0
LV Name newlv0
VG Name newvg0
LV UUID ua7BV0-2Zem-qtzq-Zeiv-DaM4-hA4K-2UKux0
LV Write Access read/write
LV Creation host, time centos6.magedu.com, 2017-08-09 16:46:39 +0800
LV Status NOT available ---查看已经处于不活动状态
LV Size 8.00 GiB
Current LE 2048
Segments 2
Allocation inherit
Read ahead sectors auto
[root@centos6 ~]#vgexport newvg0
Volume group "newvg0" successfully exported ---第四步导出卷组
halt ---第五步关机，将硬盘装入centos7
[root@centos7 ~]#echo '- - -'> /sys/class/scsi_host/host0/scan ---激活一下硬盘
[root@centos7 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 50G 0 part /
├─sda3 8:3 0 50G 0 part /app
├─sda4 8:4 0 512B 0 part
└─sda5 8:5 0 2G 0 part [SWAP]
sdb 8:16 0 20G 0 disk
└─vg0-lv0 253:0 0 18G 0 lvm /mnt/lv0
sdc 8:32 0 150G 0 disk
├─sdc1 8:33 0 15G 0 part
│ └─vg0-lv1 253:1 0 15G 0 lvm /mnt/lv1
└─sdc2 8:34 0 20G 0 part
└─vg0-lv1 253:1 0 15G 0 lvm /mnt/lv1
sdd 8:48 0 120G 0 disk
sde 8:64 0 60G 0 disk ---可以看到这个磁盘了
├─sde1 8:65 0 5G 0 part
│ └─newvg0-newlv0 253:2 0 8G 0 lvm
└─sde2 8:66 0 5G 0 part
└─newvg0-newlv0 253:2 0 8G 0 lvm
sr0 11:0 1 7.7G 0 rom /run/media/root/CentOS 7 x86_64
[root@centos7 ~]#pvscan ---第六步可以看到新的卷组处于导出状态
PV /dev/sdb VG vg0 lvm2 [20.00 GiB / 2.00 GiB free]
PV /dev/sdc1 VG vg0 lvm2 [15.00 GiB / 4.00 MiB free]
PV /dev/sdc2 VG vg0 lvm2 [20.00 GiB / 19.99 GiB free]
PV /dev/sde1 is in exported VG newvg0 [5.01 GiB / 0 free]
PV /dev/sde2 is in exported VG newvg0 [5.01 GiB / 2.02 GiB free]
Total: 5 [65.00 GiB] / in use: 5 [65.00 GiB] / in no VG: 0 [0 ]
root@centos7 ~]#vgimport newvg0 ---第七步导入卷组
Volume group "newvg0" successfully imported
root@centos7 ~]#vgchange -ay newvg0 ---第八步激活卷组
1 logical volume(s) in volume group "newvg0" now active
[root@centos7 ~]#mkdir /mnt/newlv0
[root@centos7 ~]#mount /dev/newvg0/newlv0 /mnt/newlv0/
[root@centos7 ~]#df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 52403200 15341732 37061468 30% /
devtmpfs 485268 0 485268 0% /dev
tmpfs 499980 128 499852 1% /dev/shm
tmpfs 499980 19816 480164 4% /run
tmpfs 499980 0 499980 0% /sys/fs/cgroup
/dev/sda3 52403200 1052228 51350972 3% /app
/dev/sda1 1038336 172284 866052 17% /boot
tmpfs 100000 20 99980 1% /run/user/0
/dev/sr0 8086368 8086368 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv1 15718400 71272 15647128 1% /mnt/lv1
/dev/mapper/vg0-lv0 18447056 45084 17441872 1% /mnt/lv0
/dev/mapper/newvg0-newlv0 8125880 530424 7159644 7% /mnt/newlv0
[root@centos7 ~]#cd /mnt/newlv0/
[root@centos7 newlv0]#ls
f1 lost+found
可以看到文件没有丢失
6、从逻辑卷中删除正在使用的物理分区（硬盘）
[root@centos7 ~]#vgdisplay ---先看一下卷组
--- Volume group ---
VG Name vg0
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 10
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 1
Max PV 0
Cur PV 3
Act PV 3
VG Size 54.99 GiB
PE Size 4.00 MiB
Total PE 14077
Alloc PE / Size 8448 / 33.00 GiB
Free PE / Size 5629 / 21.99 GiB ---卷组的剩余空间是否满足将硬盘或分期的空间转移到其他物理卷
VG UUID HMIGkc-kO3K-sd6j-YuPc-i6ez-IOqY-KIReKJ
[root@centos7 ~]#pvdisplay ---这里我们可以把/dev/sdc2分区中已经分配出去的2个PE转移到其他物理卷
--- Physical volume ---
PV Name /dev/sdb
VG Name vg0
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5119
Free PE 511
Allocated PE 4608
PV UUID 72dJR7-GCfL-GOHH-Tg9a-IIbl-EgTD-YLrRGz
--- Physical volume ---
PV Name /dev/sdc1
VG Name vg0
PV Size 15.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 3839
Free PE 1
Allocated PE 3838
PV UUID j8i7QQ-sSR2-bsJn-UlJj-a1jY-Ubum-KRYgWx
--- Physical volume ---
PV Name /dev/sdc2
VG Name vg0
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5119
Free PE 5117
Allocated PE 2
PV UUID DTnJdv-pV0n-p8Dz-Ku8b-gtQv-hNDI-A56LPK
[root@centos7 ~]#pvmove /dev/sdc2 ---移动/dev/sdc2中已经分配的PE空间给其他物理卷
/dev/sdc2: Moved: 100.00%
[root@centos7 ~]#pvdisplay
--- Physical volume ---
PV Name /dev/sdb
VG Name vg0
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5119
Free PE 509
Allocated PE 4610
PV UUID 72dJR7-GCfL-GOHH-Tg9a-IIbl-EgTD-YLrRGz
--- Physical volume ---
PV Name /dev/sdc1
VG Name vg0
PV Size 15.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 3839
Free PE 1
Allocated PE 3838
PV UUID j8i7QQ-sSR2-bsJn-UlJj-a1jY-Ubum-KRYgWx
--- Physical volume ---
PV Name /dev/sdc2
VG Name vg0
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5119
Free PE 5119
Allocated PE 0 ---此时/dev/sdc2分区一个PE也没有分配给逻辑卷
PV UUID DTnJdv-pV0n-p8Dz-Ku8b-gtQv-hNDI-A56LPK
[root@centos7 ~]#vgreduce vg0 /dev/sdc2 ---缩减卷组
Removed "/dev/sdc2" from volume group "vg0"
[root@centos7 ~]#pvdisplay
--- Physical volume ---
PV Name /dev/sdb
VG Name vg0
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5119
Free PE 509
Allocated PE 4610
PV UUID 72dJR7-GCfL-GOHH-Tg9a-IIbl-EgTD-YLrRGz
--- Physical volume ---
PV Name /dev/sdc1
VG Name vg0
PV Size 15.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 3839
Free PE 1
Allocated PE 3838
PV UUID j8i7QQ-sSR2-bsJn-UlJj-a1jY-Ubum-KRYgWx
"/dev/sdc2" is a new physical volume of "20.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc2
VG Name ---可以看到已经移除，不属于任何卷组
PV Size 20.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID DTnJdv-pV0n-p8Dz-Ku8b-gtQv-hNDI-A56LPK
[root@centos7 ~]#pvremove /dev/sdc2 ---删除物理卷
Labels on physical volume "/dev/sdc2" successfully wiped.
[root@centos7 ~]#pvdisplay
--- Physical volume ---
PV Name /dev/sdb
VG Name vg0
PV Size 20.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5119
Free PE 509
Allocated PE 4610
PV UUID 72dJR7-GCfL-GOHH-Tg9a-IIbl-EgTD-YLrRGz
--- Physical volume ---
PV Name /dev/sdc1
VG Name vg0
PV Size 15.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 3839
Free PE 1
Allocated PE 3838
PV UUID j8i7QQ-sSR2-bsJn-UlJj-a1jY-Ubum-KRYgWx
之后就可以将这个分区删除
7、逻辑卷快照管理
逻辑卷的快照就相当于在同一个卷组中再创建一个逻辑卷快照的空间，这个空间的大小要保证修改的文件能够存入，刚开始时逻辑卷的快照里没有数据，只是一个空间，当在逻辑卷中修改一个文件时，会把一个文件的原始状态推送到这个快照空间中保存起来。
[root@centos7 lv0]#lvcreate -L 500M -s -n lv0-snapshot -p r /dev/vg0/lv0 ---对逻辑卷lv0创建一个500M的快照，-L指定大小，-s指定是快照，-n指定名字，-p指定是只读
Using default stripesize 64.00 KiB.
Logical volume "lv0-snapshot" created.
[root@centos7 lv0]#mkdir /mnt/lv0-snapshot
[root@centos7 lv0]#mount /dev/vg0/lv0-snapshot /mnt/lv0-snapshot/ ---挂载快照
mount: /dev/mapper/vg0-lv0--snapshot is write-protected, mounting read-only
[root@centos7 lv0]#df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 52403200 15341232 37061968 30% /
devtmpfs 918932 0 918932 0% /dev
tmpfs 933644 88 933556 1% /dev/shm
tmpfs 933644 9260 924384 1% /run
tmpfs 933644 0 933644 0% /sys/fs/cgroup
/dev/sda3 52403200 1052228 51350972 3% /app
/dev/mapper/vg0-lv0 18447056 45084 17441872 1% /mnt/lv0
/dev/sda1 1038336 172284 866052 17% /boot
tmpfs 186732 12 186720 1% /run/user/0
/dev/sr0 8086368 8086368 0 100% /run/media/root/CentOS 7 x86_64
/dev/mapper/vg0-lv0--snapshot 18447056 45084 17441872 1% /mnt/lv0-snapshot
[root@centos7 lv0-snapshot]#cd /mnt/lv0 ---进入原来的lv0逻辑卷目录
[root@centos7 lv0]#ls
fstab lost+found
[root@centos7 lv0]#vim fstab ---修改一下文件内容
1 UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults
0 0
2 UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults
0 0
3 UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults
0 0
4 UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults
0 0
"fstab" 4L, 376C written
[root@centos7 lv0]#
[root@centos7 lv0]#
[root@centos7 lv0]#
[root@centos7 lv0]#
[root@centos7 lv0]#cat fstab ---修改之后的内容
UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults 0 0
UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults 0 0
UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults 0 0
UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults 0 0
[root@centos7 lv0]#
0 0
[root@centos7 lv0]#cd /mnt/lv0-snapshot/ ---进入快照的目录
[root@centos7 lv0-snapshot]#ls
fstab lost+found
[root@centos7 lv0-snapshot]#cat fstab ---可以看到已经将原始的内容保存到其中
#
# /etc/fstab
# Created by anaconda on Fri Jul 14 11:16:04 2017
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults 0 0
UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults 0 0
UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults 0 0
UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults 0 0
[root@centos6 ~]#lvconvert --merge /dev/vg0/lv0-snapshot ---恢复快照
Merging of volume vg0/lv0-snapshot started.
lv1: Merged: 100.00%
[root@centos6 lv1]#cd /mnt/lv0
[root@centos6 lv1]#ls
etc fstab
[root@centos6 lv0]#cat fstab ---可以看到文件又恢复到原来的状态，没有丢失
总结：在恢复快照之前一定要先取消挂载，包括逻辑卷的挂载和快照的挂载都要取消，否则无法恢复快照。这个是在练习中经常出现的错误。
#
# /etc/fstab
# Created by anaconda on Fri Jul 14 11:16:04 2017
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults 0 0
UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults 0 0
UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults 0 0
UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults 0 0
UUID=fca04a06-6e33-41bb-8902-cc89b908ae22 /mnt/lv0 ext4 defaults 0 0
总结：在修改逻辑卷上的文件时会将原文件数据推送至快照中，在生产中一般不会使用快照。因为这样会影响服务器的性能。相当于在修改的时候会把原数据输出到快照。
8、删除逻辑卷的步骤
从上往下删除，跟创建的时候相反
[root@centos7 lv1]#lvdisplay
--- Logical volume ---
LV Path /dev/vg0/lv1
LV Name lv1
VG Name vg0
LV UUID RAIOfB-sJ1U-0wGj-FPjn-53SZ-rBeE-AvsvBp
LV Write Access read/write
LV Creation host, time centos7.magedu.com, 2017-08-12 12:00:14 +0800
LV Status available
# open 1
LV Size 15.00 GiB
Current LE 3840
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@centos7 ~]#umount /mnt/lv1 ---先取消挂载
[root@centos7 ~]#lvremove /dev/vg0/lv1 ---删除逻辑卷
Do you really want to remove active logical volume vg0/lv1? [y/n]: y
Logical volume "lv1" successfully removed
[root@centos7 ~]#vgremove vg0
Volume group "vg0" successfully removed
[root@centos7 ~]#pvs
PV VG Fmt Attr PSize PFree
/dev/sdb lvm2 --- 20.00g 20.00g
/dev/sdc1 lvm2 --- 15.00g 15.00g
[root@centos7 ~]#pvremove /dev/sd{b,c1} ---删除物理卷
Labels on physical volume "/dev/sdb" successfully wiped.
Labels on physical volume "/dev/sdc1" successfully wiped.
之后就可以删除分区或者拔除硬盘了。