一、逻辑卷扩展
[root@lxjtest /]# umount /testLVM/
[root@lxjtest /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 3.7G 896M 2.9G 24% /
devtmpfs 910M 0 910M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.4M 912M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/sda1 297M 114M 184M 39% /boot
tmpfs 184M 0 184M 0% /run/user/0
[root@lxjtest /]#
第1步：把上个试验中的逻辑卷fuck_lv1扩展至300MB
[root@lxjtest /]# lvdisplay testVG
--- Logical volume ---
LV Path /dev/testVG/fuck_lv1
LV Name fuck_lv1
VG Name testVG
LV UUID RKzHdO-NX2i-Za40-kWNg-RIox-yi9j-z9251R
LV Write Access read/write
LV Creation host, time lxjtest.rusky.com, 2017-08-07 23:35:10 -0400
LV Status available
# open 0
LV Size 200.00 MiB
Current LE 50
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
[root@lxjtest /]# lvs testVG
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
fuck_lv1 testVG -wi-a----- 200.00m
[root@lxjtest /]# lvextend -L 300M /dev/testVG/fuck_lv1
Size of logical volume testVG/fuck_lv1 changed from 200.00 MiB (50 extents) to 300.00 MiB (75 extents).
Logical volume fuck_lv1 successfully resized.
[root@lxjtest /]# lvs testVG
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
fuck_lv1 testVG -wi-a----- 300.00m
[root@lxjtest /]#
第2步：检查磁盘容量，重置磁盘容量
[root@lxjtest /]# e2fsck -f /dev/testVG/fuck_lv1
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/testVG/fuck_lv1: 12/51200 files (0.0% non-contiguous), 12116/204800 blocks
[root@lxjtest /]# resize2fs /dev/testVG/fuck_lv1
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/testVG/fuck_lv1 to 307200 (1k) blocks.
The filesystem on /dev/testVG/fuck_lv1 is now 307200 blocks long.
第3步：重新挂载硬盘设备并查看挂载状态
[root@lxjtest /]# mount -a
[root@lxjtest /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 3.7G 897M 2.9G 24% /
devtmpfs 910M 0 910M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.4M 912M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/sda1 297M 114M 184M 39% /boot
tmpfs 184M 0 184M 0% /run/user/0
/dev/mapper/testVG-fuck_lv1 287M 2.1M 266M 1% /testLVM
二、逻辑卷收缩
缩小逻辑卷之前，先备份数据，然后检查文件系统完整性，再卸载文件系统，之后再来压缩。
[root@lxjtest /]# umount /testLVM/
[root@lxjtest /]# e2fsck -f /dev/testVG/fuck_lv1
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/testVG/fuck_lv1: 12/77824 files (0.0% non-contiguous), 15988/307200 blocks
[root@lxjtest /]# resize2fs /dev/testVG/fuck_lv1 100M
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/testVG/fuck_lv1 to 102400 (1k) blocks.
The filesystem on /dev/testVG/fuck_lv1 is now 102400 blocks long.
[root@lxjtest /]# lvreduce -L 100M /dev/testVG/fuck_lv1
WARNING: Reducing active logical volume to 100.00 MiB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce fuck_lv1? [y/n]: y
Size of logical volume testVG/fuck_lv1 changed from 300.00 MiB (75 extents) to 100.00 MiB (25 extents).
Logical volume fuck_lv1 successfully resized.
[root@lxjtest /]# lvs testVG
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
fuck_lv1 testVG -wi-a----- 100.00m
[root@lxjtest /]#
最后，重新挂载并查看文件系统：
[root@lxjtest /]# mount -a
[root@lxjtest /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 3.7G 896M 2.9G 24% /
devtmpfs 910M 0 910M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.4M 912M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/sda1 297M 114M 184M 39% /boot
tmpfs 184M 0 184M 0% /run/user/0
/dev/mapper/testVG-fuck_lv1 93M 1.6M 85M 2% /testLVM
三、逻辑卷快照
LVM逻辑卷管理器还具备有“快照卷”的功能，这项功能很类似于虚拟机软件的还原时间点功能。例如可以对某一个LV逻辑卷设备做一次快照，如果今后发现数据被改错了，咱们可以把之前做好的快照卷进行覆盖还原，LVM逻辑卷管理器的快照功能有两项特点，第一是快照卷的大小应该尽量等同于LV逻辑卷的容量，第二是快照功能仅一次有效，一旦被还原后则会被自动立即删除，首先应当查看下卷组的信息：
[root@lxjtest testLVM]# ls -lht
total 46M
drwx------. 2 root root 12K Aug 7 23:51 lost+found
-rw-r--r--. 1 root root 46M Apr 5 2015 firefox-37.0.1.tar.bz2
[root@lxjtest testLVM]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 3.7G 898M 2.9G 24% /
devtmpfs 910M 0 910M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.4M 912M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/sda1 297M 114M 184M 39% /boot
tmpfs 184M 0 184M 0% /run/user/0
/dev/mapper/testVG-fuck_lv1 93M 48M 39M 55% /testLVM
/dev/sr0 3.8G 3.8G 0 100% /mnt
在创建快照前，先在/testLVM中放入一些文件，以对比快照还原结果
[root@lxjtest testLVM]# pwd
/testLVM
[root@lxjtest testLVM]# ls -lht
total 46M
drwx------. 2 root root 12K Aug 7 23:51 lost+found
-rw-r--r--. 1 root root 46M Apr 5 2015 firefox-37.0.1.tar.bz2
第1步：使用-s参数来生成一个快照卷，使用-L参数来指定切割的大小，另外要记得在后面写上这个快照是针对那个LV逻辑卷设备做的。
[root@lxjtest testLVM]# lvcreate -L 100M -s -n SNAP /dev/testVG/fuck_lv1
Logical volume "SNAP" created.
--- Logical volume ---
LV Path /dev/testVG/fuck_lv1
LV Name fuck_lv1
VG Name testVG
LV UUID RKzHdO-NX2i-Za40-kWNg-RIox-yi9j-z9251R
LV Write Access read/write
LV Creation host, time lxjtest.rusky.com, 2017-08-07 23:35:10 -0400
LV snapshot status source of
SNAP [active]
LV Status available
# open 0
LV Size 100.00 MiB
Current LE 25
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/testVG/SNAP
LV Name SNAP
VG Name testVG
LV UUID 7eeuaw-FMmH-KA1o-45CG-0x4J-B3tK-AOJqFv
LV Write Access read/write
LV Creation host, time lxjtest.rusky.com, 2017-08-08 04:20:52 -0400
LV snapshot status active destination for fuck_lv1
LV Status available
# open 0
LV Size 100.00 MiB
Current LE 25
COW-table size 100.00 MiB
COW-table LE 25
Allocated to snapshot 0.09%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:5
（略）
快照创建完成之后，删除之前在/testLVM中放入的文件。下面我们使用快照卷SNAP来还原之前的文件。
第2步：为了校验SNAP快照卷的效果，需要对逻辑卷进行快照合并还原操作，在这之前记得先卸载掉逻辑卷设备与目录的挂载~
[root@lxjtest /]# cd testLVM/
[root@lxjtest testLVM]#rm firefox-37.0.1.tar.bz2 --删除原文件
[root@lxjtest testLVM]#touch testNewFile --创建新文件
[root@lxjtest testLVM]# ls
lost+found tesstNewFile
[root@lxjtest testLVM]# cd /
[root@lxjtest /]# umount /testLVM/ --卸载
[root@lxjtest /]# lvconvert --merge /dev/testVG/SNAP --快照还原
Merging of volume SNAP started.
fuck_lv1: Merged: 99.9%
fuck_lv1: Merged: 100.0%
[root@lxjtest /]# mount -a
[root@lxjtest /]# cd testLVM/
[root@lxjtest testLVM]# ls --原文件已被还原出来。
firefox-37.0.1.tar.bz2 lost+found
lvconvert之后，快照卷/dev/testVG/SNAP会被自动删除掉，并且刚刚在逻辑卷设备被快照后再创建出来的100M垃圾文件也被清除了。
[root@lxjtest testLVM]# lvdisplay
--- Logical volume ---
LV Path /dev/testVG/fuck_lv1
LV Name fuck_lv1
VG Name testVG
LV UUID RKzHdO-NX2i-Za40-kWNg-RIox-yi9j-z9251R
LV Write Access read/write
LV Creation host, time lxjtest.rusky.com, 2017-08-07 23:35:10 -0400
LV Status available
# open 1
LV Size 100.00 MiB
Current LE 25
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
（略）
[root@lxjtest testLVM]#
四、删除逻辑卷
当生产环境中想要重新部署或者不需要再继续使用LVM逻辑卷管理器了，除了提前备份好重要数据信息，还必须依次删除LV逻辑卷、VG卷组后再移除PV物理卷设备，这样的顺序不可颠倒。
第1步：取消逻辑卷与目录的挂载关联，删除配置文件中永久生效的设备参数。
[root@lxjtest ~]# umount /testLVM/
[root@lxjtest ~]# vi /etc/fstab
#
# /etc/fstab
# Created by anaconda on Tue Aug 1 04:28:47 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
#
/dev/mapper/rhel-root / xfs defaults 0 0
UUID=e7987771-c54c-4b36-8a5c-8e71f129c3fe /boot xfs defaults 0 0
/dev/mapper/rhel-swap swap swap defaults 0 0
#/dev/testVG/fuck_lv1 /testLVM ext4 defaults 0 0
#删除或注释该行
第2步：把LV逻辑卷设备删除，需要手工输入y来确认操作
[root@lxjtest ~]# lvdisplay
--- Logical volume ---
LV Path /dev/testVG/fuck_lv1
LV Name fuck_lv1
VG Name testVG
LV UUID RKzHdO-NX2i-Za40-kWNg-RIox-yi9j-z9251R
LV Write Access read/write
LV Creation host, time lxjtest.rusky.com, 2017-08-07 23:35:10 -0400
LV Status available
# open 0
LV Size 100.00 MiB
Current LE 25
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
（略）
[root@lxjtest ~]# lvremove /dev/testVG/fuck_lv1
Do you really want to remove active logical volume fuck_lv1? [y/n]: y
Logical volume "fuck_lv1" successfully removed
[root@lxjtest ~]#
第3步：把VG卷组删除，此处只需写卷组名称即可，而无需设备完整绝对路径
[root@lxjtest ~]# vgdisplay
--- Volume group ---
VG Name testVG
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 10
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 3.99 GiB
PE Size 4.00 MiB
Total PE 1022
Alloc PE / Size 0 / 0
Free PE / Size 1022 / 3.99 GiB
VG UUID b3mykq-kcsp-Hdh4-rAos-vutt-ontI-6AWJ5K
（略）
[root@lxjtest ~]#
[root@lxjtest ~]# vgremove testVG
Volume group "testVG" successfully removed
[root@lxjtest ~]#
第4步：把PV物理卷设备移除：
[root@lxjtest ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name rhel
PV Size 4.71 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 1204
Free PE 0
Allocated PE 1204
PV UUID V3kA1X-l7dr-03p4-HZcu-Ebj3-FRvb-r5vGMd
"/dev/sdb" is a new physical volume of "2.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb
VG Name
PV Size 2.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID InfACr-fq1t-yi95-K1K3-dOHU-uezl-gfiPVa
"/dev/sdc" is a new physical volume of "2.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc
VG Name
PV Size 2.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID aOtJga-uWop-ldnv-xIcj-TcLE-aq18-SrJO3p
[root@lxjtest ~]# pvremove /dev/sdb /dev/sdc
Labels on physical volume "/dev/sdb" successfully wiped
Labels on physical volume "/dev/sdc" successfully wiped
[root@lxjtest ~]#
可以再分别执行下lvdisplay、vgdisplay、pvdisplay命令来查看逻辑卷管理器信息，操作正确则会不能再看到我们创建的逻辑卷设备信息了。
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