LVM实例及快照相关

LVM创建 pv--->vg---->lv---->快照
创建前准备了四块1g硬盘分别为：sdb sdc sdd sde，并分别给四块盘划分了将近1G的空间，并指定了分区系统类型为8e（即Linux LVM）

[root@localhost ~]# fdisk /dev/sdb
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-130, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-130, default 130): +999M

Command (m for help): t 指定类型
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): w 保存退出
The partition table has been altered!

然后依次对sdc sdd sde做一样的操作

[root@localhost ~]# fdisk -l|grep "^/dev/sd"
/dev/sda1 * 1 39 307200 83 Linux
/dev/sda2 39 2358 18631680 83 Linux
/dev/sda3 2358 2611 2031616 82 Linux swap / Solaris
/dev/sdb1 1 128 1028128+ 8e Linux LVM
/dev/sdc1 1 128 1028128+ 8e Linux LVM
/dev/sdd1 1 128 1028128+ 8e Linux LVM
/dev/sde1 1 128 1028128+ 8e Linux LVM
以上红色显示的是即将用于创建lvm的分区

First 创建pv

[root@localhost ~]# pvcreate /dev/sd{b,c,d,e}1 #创建 PV
Physical volume "/dev/sdb1" successfully created
Physical volume "/dev/sdc1" successfully created
Physical volume "/dev/sdd1" successfully created
Physical volume "/dev/sde1" successfully created

[root@localhost ~]# pvs 查看pv
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 a-- 1004.03m 1004.03m
/dev/sdc1 lvm2 a-- 1004.03m 1004.03m
/dev/sdd1 lvm2 a-- 1004.03m 1004.03m
/dev/sde1 lvm2 a-- 1004.03m 1004.03m

[root@localhost ~]# pvdisplay 相对pvs来说显示的更详细，

以下是/dev/sdb1的显示内容
"/dev/sdb1" is a new physical volume of "1004.03 MiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 1004.03 MiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 8etjmo-mVi0-ncst-Em9d-pMW0-z0Ol-q4fX8v

pvremove /dev/sdb1 即可删除
pvcreate /dev/sdb1 则可再加进来

Second 创建pv后创建vg

[root@localhost ~]# vgcreate myvg /dev/sd{b,c,d}1 这里我们先加进来3块盘，另一块用于演示其他操作
Volume group "myvg" successfully created
如果要修改PE大小：可以使用-s参数 默认是4m
查看
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
myvg 3 0 0 wz--n- 2.93g 2.93g
[root@localhost ~]# vgdisplay 同样也比vgs显示的详细
--- Volume group ---
VG Name myvg
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 2.93 GiB
PE Size 4.00 MiB
Total PE 750
Alloc PE / Size 0 / 0
Free PE / Size 750 / 2.93 GiB
VG UUID hbiddu-b9z4-WTxe-CwYK-WrNu-J0Af-tgLWZR
[root@localhost ~]# vgextend myvg /dev/sde1 添加硬盘到vg 增加磁盘没什么风险
Volume group "myvg" successfully extended
[root@localhost ~]# vgs 刚才是3个pv 现在4个且容量也增加了
VG #PV #LV #SN Attr VSize VFree
myvg 4 0 0 wz--n- 3.91g 3.91g
下面是移除磁盘，这是我没要考虑是否磁盘上有数据，如果有移到其他pv，然后移除
[root@localhost ~]# pvmove /dev/sdb1 ##移走数据
No data to move for myvg
[root@localhost ~]# vgreduce myvg /dev/sdb1 ##mypv移除/dev/sdb1
Removed "/dev/sdb1" from volume group "myvg"
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
myvg 3 0 0 wz--n- 2.93g 2.93g
Third 创建逻辑卷lv，及扩展大小
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
myvg 4 0 0 wz--n- 3.91g 3.91g
我们查看一共有不到4G的空间，创建的lv大小不能超过上面vg的大小
[root@localhost ~]# lvcreate -L 2G -n mylv myvg ##在myvg上创建一个mylv的逻辑卷大小2G
Logical volume "mylv" created[root@localhost ~]# lvs #查看
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
mylv myvg -wi-a----- 2.00g
[root@localhost ~]# lvdisplay 查看
--- Logical volume ---
LV Path /dev/myvg/mylv
LV Name mylv
VG Name myvg
LV UUID PPPW3e-xAiz-CMNM-RV2o-i8H1-yfIB-9g4KG2
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2015-06-06 21:24:36 -0700
LV Status available
# open 0
LV Size 2.00 GiB
Current LE 512
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
lv的访问路径：(此两者均为符号链接，指向的文件为/dev/dm-#)
1./dev/VG_name/LV_name
/dev/myvg/mylv
2./dev/mapper/VG_name-LV_name
/dev/mapper/myvg-mylv
[root@localhost ~]# ll /dev/dm-*
brw-rw---- 1 root disk 253, 0 Jun 6 21:24 /dev/dm-0
[root@localhost ~]# ll /dev/myvg/
lrwxrwxrwx 1 root root 7 Jun 6 21:24 mylv -> ../dm-0
[root@localhost ~]# ll /dev/mapper
lrwxrwxrwx 1 root root 7 Jun 6 21:24 myvg-mylv -> ../dm-0

lv创建好就是一个文件系统，我们就可以使用它了
[root@localhost ~]# mke2fs -t ext4 /dev/myvg/mylv
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
131072 inodes, 524288 blocks
26214 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=536870912
16 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
格式化后创建目录挂载吧：
[root@localhost ~]# mkdir /mnt/mylv
[root@localhost ~]# mount /dev/myvg/mylv /mnt/mylv
[root@localhost ~]# mount
/dev/sda2 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/sda1 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
vmware-vmblock on /var/run/vmblock-fuse type fuse.vmware-vmblock (rw,nosuid,nodev,default_permissions,allow_other)
/dev/mapper/myvg-mylv on /mnt/mylv type ext4 (rw)
如果想要长期使用，命令挂载只是暂时的，还要添加到/etc/fstab文件中最后一行增加：
/dev/myvg/mylv /mnt/mylv ext4 defaults 0 0
pv总空间为3.91G，现在只划给mylv 2G空间，如果不够用可以扩展mylv
1. lvextend 扩展物理边界 [root@localhost ~]# lvextend -L 3G /dev/myvg/mylv ###这里表示扩展到3G Extending logical volume mylv to 3.00 GiB Logical volume mylv successfully resized
[root@localhost ~]# df -hFilesystem Size Used Avail Use% Mounted on/dev/sda2 18G 2.9G 14G 18% /tmpfs 495M 0 495M 0% /dev/shm/dev/sda1 291M 34M 242M 13% /boot/dev/mapper/myvg-mylv 2.0G 67M 1.9G 4% /mnt/mylv 2.resizefs 扩展逻辑边界 [root@localhost ~]# resize2fs /dev/myvg/mylv ###这里表示扩展至物理边界大小
resize2fs 1.41.12 (17-May-2010)Filesystem at /dev/myvg/mylv is mounted on /mnt/mylv; on-line resizing requiredold desc_blocks = 1, new_desc_blocks = 1Performing an on-line resize of /dev/myvg/mylv to 786432 (4k) blocks.The filesystem on /dev/myvg/mylv is now 786432 blocks long.
[root@localhost ~]# df -hFilesystem Size Used Avail Use% Mounted on/dev/sda2 18G 2.9G 14G 18% /tmpfs 495M 0 495M 0% /dev/shm/dev/sda1 291M 34M 242M 13% /boot/dev/mapper/myvg-mylv 3.0G 67M 2.8G 3% /mnt/mylv 缩减很危险！！！！！
缩减要离线，首先卸载 umount /mnt/mylv

1.先确定缩减的目录数据有多少，并确定对应的目标逻辑卷大小中有足够的空间可容纳原来的所有数据

[root@localhost ~]# du -sh /mnt/mylv

20K/mnt/mylv
2.先减少文件系统，并要执行强制检测

e2fsck -f
[root@localhost ~]# e2fsck -f /dev/myvg/mylve2fsck 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/myvg/mylv: 11/196608 files (0.0% non-contiguous), 29500/786432 blocks 3.缩减边界

resize2fs device

[root@localhost ~]# resize2fs /dev/myvg/mylv 1Gresize2fs 1.41.12 (17-May-2010)Resizing the filesystem on /dev/myvg/mylv to 262144 (4k) blocks.The filesystem on /dev/myvg/mylv is now 262144 blocks long. 4.缩减物理边界

lvreduce -L 1G /dev/myvg/mylv

[root@localhost ~]# lvreduce -L 1G /dev/myvg/mylv WARNING: Reducing active logical volume to 1.00 GiB THIS MAY DESTROY YOUR DATA (filesystem etc.)Do you really want to reduce mylv? [y/n]: y Reducing logical volume mylv to 1.00 GiB Logical volume mylv successfully resized
[root@localhost ~]# mount /dev/myvg/mylv /mnt/mylv
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 18G 2.9G 14G 18% /
tmpfs 495M 0 495M 0% /dev/shm
/dev/sda1 291M 34M 242M 13% /boot
/dev/mapper/myvg-mylv 1008M 67M 891M 7% /mnt/mylv
快照卷：只能读，不能写

注意：快照卷是对某逻辑卷
[root@localhost ~]# mount -o remount,ro /dev/myvg/mylv /mnt/mylv ##先改成只读
[root@localhost ~]# lvcreate -L 1G -n mylv-snap -p r -s /dev/myvg/mylv ##对mylv做快照为mylv-snap 大小为1G
[root@localhost ~]# mount -o remount,rw /dev/myvg/mylv /mnt/mylv #快照完，立刻改为读写或者一个命令行直接执行者三个命令，或者写脚本
Logical volume "mylv-snap" created

[root@localhost ~]# mount /dev/myvg/mylv-snap /mnt/snap/ 挂载快照
mount: block device /dev/mapper/myvg-mylv--snap is write-protected, mounting read-only

如果不想用了，要删除怎么办？？
umount /mnt/snap
lvremove /dev/myvg/mylv-snap

另外还有：pvremove vgremove等删除命令，可以用man 查看