LVM

LVM一：建立PV
# pvcreate /dev/sdb{6,7,8,9}
# pvscan 查看建立的PV
# pvdisplay 查看详细信息

二：在pv基础上建立VG
（1） 把/dev/sdb{6,7,8}建立一个VG，名为testvg
# vgcreate -s 16M testvg /dev/sdb{6,7,8}
# vgscan

（2） 查看建立的vg卷
[root@centos ~]# vgdisplay
--- Volume group ---
VG Name testvg
System ID
Format lvm2
Metadata Areas 3
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 3
Act PV 3
VG Size 3.00 GiB
PE Size 16.00 MiB
Total PE 192
Alloc PE / Size 0 / 0
Free PE / Size 192 / 3.00 GiB
VG UUID 9KKogl-sH9a-SV64-RALb-LVx5-n9FO-VtFA1D

(3)把一个/sdb9增加到testvg卷
# vgextend testvg /dev/sdb9

（4）再次查看vg卷,PE为256个
[root@centos ~]# vgdisplay
--- Volume group ---
VG Name testvg
System ID
Format lvm2
Metadata Areas 4
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 4
Act PV 4
VG Size 4.00 GiB
PE Size 16.00 MiB
Total PE 256
Alloc PE / Size 0 / 0
Free PE / Size 256 / 4.00 GiB PE块和容量都增加了
VG UUID 9KKogl-sH9a-SV64-RALb-LVx5-n9FO-VtFA1D

三：在VG的基础上建立LV
（1）建立testlv，PE为256个。
# lvcreate -l 256 -n testlv testvg
（2）格式化和挂载
# mke2fs -t ext4 /dev/testvg/testlv
（3）建立挂载点，并挂载
# mkdir /mnt/lvm
# mount /dev/testvg/testlv /mnt/lvm

（4）查看挂在后的lv
[root@centos ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/testvg-testlv
3.9G 8.0M 3.7G 1% /mnt/lvm

四：LV 扩容
（1）以sdb10 作为扩容盘，新建立一个PV。
# pvcreate /dev/sdb10

（2）查看建立的pv
[root@centos ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 vg_centos lvm2 a-- 19.51g 0
/dev/sdb10 lvm2 --- 3.93g 3.93g
/dev/sdb6 testvg lvm2 a-- 1.00g 0
/dev/sdb7 testvg lvm2 a-- 1.00g 0
/dev/sdb8 testvg lvm2 a-- 1.00g 0
/dev/sdb9 testvg lvm2 a-- 1.00g 0

(2) 利用vgextend 把/sdb10 增加到testvg里
# vgextend testvg /dev/sdb10

（3）再次查看
[root@centos ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 vg_centos lvm2 a-- 19.51g 0
/dev/sdb10 testvg lvm2 a-- 3.92g 3.92g 已经添加到卷组testvg了
/dev/sdb6 testvg lvm2 a-- 1.00g 0
/dev/sdb7 testvg lvm2 a-- 1.00g 0
/dev/sdb8 testvg lvm2 a-- 1.00g 0
/dev/sdb9 testvg lvm2 a-- 1.00g 0

(4) 利用vgdisplay查看增加的块
# vgdisplay
--- Volume group ---
VG Name testvg
System ID
Format lvm2
Metadata Areas 5
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 5
Act PV 5
VG Size 7.92 GiB
PE Size 16.00 MiB
Total PE 507
Alloc PE / Size 256 / 4.41 GiB
Free PE / Size 251 / 3.92 GiB 增加的251个PE 块
VG UUID d6YPIx-vfID-TL5H-Fmcy-nZVi-G7uq-LTVgQ0

（5）利用lvresize来增加PE块到LV
# lvresize -l +251 /dev/testvg/testlv
Size of logical volume testvg/testlv changed from 4.00 GiB (256 extents) to 7.92 GiB (507 extents).

（6）利用 lvdisplay 查看增加后的容量。

（7）用resize2fs 讲文件系统里容量确实增加
# resize2fs /dev/testvg/testlv
（8）# df -h /mnt/lvm/ 增量成功。
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/testvg-testlv
7.7G 9.0M 7.3G 1% /mnt/lvm

五：缩小LV（1）假如我们要把/dev/sdb6 抽离出来，先找出容量和PE块数[root@centos ~]# pvdisplay --- Physical volume --- PV Name /dev/sdb6 VG Name testvg PV Size 1.01 GiB / not usable 11.41 MiB Allocatable yes (but full) PE Size 16.00 MiB Total PE 64 Free PE 0 Allocated PE 64 PV UUID B3LTgT-zLCO-hseh-EdlT-jm3T-Z57d-WqesPv (2）卸载lvm[root@centos ~]# umount /mnt/lvm/ (3)强制检查LV[root@centos ~]# e2fsck -f /dev/testvg/testlv e2fsck 1.41.12 (17-May-2010)Pass 1: Checking inodes, blocks, and sizesPass 2: Checking directory structurePass 3: Checking directory connectivityPass 4: Checking reference countsPass 5: Checking group summary information/dev/testvg/testlv: 11/524288 files (0.0% non-contiguous), 67983/2076672 blocks[root@centos ~]# resize2fs /dev/testvg/testlv 6Gresize2fs 1.41.12 (17-May-2010)Resizing the filesystem on /dev/testvg/testlv to 1572864 (4k) blocks.The filesystem on /dev/testvg/testlv is now 1572864 blocks long. (4)缩小分区到6G[root@centos ~]# resize2fs /dev/testvg/testlv 6G 缩小到6G 这个最好总的PV减去/dev/sdb6后的大小，缩减太多容易浪费。比哪缩减到6900M，我这时缩减多了 （5）缩小LV逻辑边界到6G[root@centos ~]# lvreduce -L 6G /dev/testvg/testlv LV缩小到6G WARNING: Reducing active logical volume to 6.00 GiB THIS MAY DESTROY YOUR DATA (filesystem etc.)Do you really want to reduce testlv? [y/n]: y Size of logical volume testvg/testlv changed from 7.92 GiB (507 extents) to 6.00 GiB (384 extents). Logical volume testlv successfully resized （6）再次挂载LV[root@centos ~]# mount /dev/testvg/testlv /mnt/lvm[root@centos ~]# df -h /mnt/lvmFilesystem Size Used Avail Use% Mounted on/dev/mapper/testvg-testlv 5.8G 8.0M 5.5G 1% /mnt/lvm （7）查看PV上的空闲块[root@centos lvm]# pvdisplay--- Physical volume --- PV Name /dev/sdb10 VG Name testvg PV Size 3.93 GiB / not usable 8.06 MiB Allocatable yes PE Size 16.00 MiB Total PE 251 Free PE 123 移除的空闲块在/dev/sdb10上，这个自己注意观察 Allocated PE 128 PV UUID GXWe7H-uNPt-mERp-gKk6-kz70-yUtj-XLXp0y
(7)把sdb6上占用块移动到空闲块/sdb10上[root@centos lvm]# pvmove /dev/sdb6 /dev/sdb10 /dev/sdb6: Moved: 0.0% /dev/sdb6: Moved: 73.4% /dev/sdb6: Moved: 100.0% （8）把/dev/sdb6从vg中移出去[root@centos lvm]# vgreduce testvg /dev/sdb6 从testvg中移出去 Removed "/dev/sdb6" from volume group "testvg" [root@centos lvm]# pvscan PV /dev/sdb7 VG testvg lvm2 [1.00 GiB / 0 free] PV /dev/sdb8 VG testvg lvm2 [1.00 GiB / 0 free] PV /dev/sdb9 VG testvg lvm2 [1.00 GiB / 0 free] PV /dev/sdb10 VG testvg lvm2 [3.92 GiB / 944.00 MiB free] PV /dev/sda2 VG vg_centos lvm2 [19.51 GiB / 0 free] PV /dev/sdb6 lvm2 [1.01 GiB] （9）把/sdb6/从PV中移出[root@centos lvm]# pvremove /dev/sdb6 从PV中移除去 Labels on physical volume "/dev/sdb6" successfully wiped （10）在pv中已经没有sdb6了[root@centos lvm]# pvscan PV /dev/sdb7 VG testvg lvm2 [1.00 GiB / 0 free] PV /dev/sdb8 VG testvg lvm2 [1.00 GiB / 0 free] PV /dev/sdb9 VG testvg lvm2 [1.00 GiB / 0 free] PV /dev/sdb10 VG testvg lvm2 [3.92 GiB / 944.00 MiB free] PV /dev/sda2 VG vg_centos lvm2 [19.51 GiB / 0 free] Total: 5 [26.43 GiB] / in use: 5 [26.43 GiB] / in no VG: 0 [0 已经没有/dev/sdb6了(11)pv里剩下的块在加回到LV里。避免浪费。[root@centos ~]# lvresize -l +59 /dev/testvg/testlv Size of logical volume testvg/testlv changed from 6.00 GiB (384 extents) to 6.92 GiB (443 extents). Logical volume testlv successfully resized 快照的建立：1：查看VG上已经没有空闲PE块了2：把 /dev/sdb6添加到VG中[root@centos ~]# pvcreate /dev/sdb6[root@centos ~]# vgextend testvg /dev/sdb6 Volume group "testvg" successfully extended 3：查看VG中空闲PE[root@centos ~]# vgdisplay --- Volume group --- VG Name testvg System ID Format lvm2 Metadata Areas 5 Metadata Sequence No 20 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 1 Max PV 0 Cur PV 5 Act PV 5 VG Size 7.92 GiB PE Size 16.00 MiB Total PE 507 Alloc PE / Size 443 / 6.92 GiB Free PE / Size 64 / 1.00 GiB VG UUID 9KKogl-sH9a-SV64-RALb-LVx5-n9FO-VtFA1D 3：建立快照区：[root@centos ~]# lvcreate -l 64 -s -n testss /dev/testvg/testlv Logical volume "testss" created 注解：-l :用来指定用多少PE块 -s :用来说明使用快照功能 -n :用来指定快照区的名称，名称后接的LV完整路径 4：查看建立的快照区[root@centos ~]# lvdisplay /dev/testvg/testss --- Logical volume --- LV Path /dev/testvg/testss LV Name testss VG Name testvg LV UUID UI89Oh-fqtD-vNtD-LQ6v-ikGH-Vt6x-0BJK5g LV Write Access read/write LV Creation host, time centos, 2016-03-24 16:46:16 +0800 LV snapshot status active destination for testlv LV Status available # open 0 LV Size 6.92 GiB 被快照的LV磁盘容量 Current LE 443 COW-table size 1.00 GiB 快照区的大小 COW-table LE 64 快照区的PE数量 Allocated to snapshot 0.00% Snapshot chunk size 4.00 KiB Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2 5：建立挂载快照挂载点，并挂载[root@centos lvm]# mkdir /mnt/snapshot[root@centos lvm]# mount /dev/testvg/testss /mnt/snapshot/ 6：查看挂载同步[root@centos lvm]# df -hFilesystem Size Used Avail Use% Mounted on/dev/mapper/testvg-testlv 6.7G 45M 6.3G 1% /mnt/lvm/dev/mapper/testvg-testss 6.7G 45M 6.3G 1% /mnt/snapshot7：卸载挂载的快照[root@centos lvm]# umount /mnt/snapshot/ 8：测试,我添加和删除一些LVM中的文件，再次挂载上快照，会发现不一样了 [root@centos lvm]# mount /dev/testvg/testss /mnt/snapshot/[root@centos lvm]# df -hFilesystem Size Used Avail Use% Mounted on/dev/mapper/testvg-testlv 6.7G 628M 5.8G 10% /mnt/lvm/dev/mapper/testvg-testss 6.7G 45M 6.3G 1% /mnt/snapshot 9：我们把快照里的文件备份打包到/backups。[root@centos ]# mkdir -p /backups/[root@centos ]# cd /mnt/snapshot/[root@centos snapshot]# tar -jcv -f /backups/lvm.tar.bz2 * 10：还原时卸载掉快照，并删除快照[root@centos ~]# umount /mnt/snapshot/[root@centos ~]# lvremove /dev/testvg/testss Do you really want to remove active logical volume testss? [y/n]: y Logical volume "testss" successfully removed 11：卸载LVM，并格式化挂载LVM。最后解压数据[root@centos ~]# umount /mnt/lvm/[root@centos ~]# mke2fs -t ext4 /dev/testvg/testlv [root@centos backups]# cd /backups/[root@centos backups]# tar -jxf lvm.tar.bz2 -C /mnt/lvm/ 12：最后重新挂载LVM和快照，数据就会同步了。


快照损坏的再次同步LVM就行了# umount /mnt/snapshot# lvremove /dev/testvg/testss/查看VG中的空闲PE# vgdisplay # lvcreate -s -l 64 -n testss /dev/testvg/testlv # mount /dev/testvg/testss /mnt/snapshot/# ll /mnt/snapshot/