Linux文件系统LVM建立
LVM的建立过程：
通过fdisk分区：
1.划分物理分区并把分区格式变为lvm：可参考博客：http://blog.csdn.net/dream_ya/article/details/79158238
[root@dream /]# fdisk -l
Device Boot Start End Blocks Id System
/dev/vdb1 2048 2099199 1048576 8e Linux LVM
/dev/vdb2 2099200 4196351 1048576 8e Linux LVM
pvs|pvdisplay ###查看pv
vgs|vgdisplay ###查看vg
lvs|lvdisplay ###查看lvm通过watch命令监控状态
watch -n 1 \
'echo "=== pvinfo ==="\
;pvs\
;echo "=== vginfo ==="\
;vgs\
;echo === lvinfo ===\
;lvs'
建立pv
[root@dream /]# pvcreate /dev/vdb1 ###把/dev/vdb1建立成pv
WARNING: xfs signature detected on /dev/vdb1 at offset 0. Wipe it? [y/n] y
Wiping xfs signature on /dev/vdb1.
Physical volume "/dev/vdb1" successfully created
建立vg
[root@dream /]# vgcreate -s 2M vg0 /dev/vdb1 ###-s:vg中pe（最小单位）的大小，名字取为vg0
Volume group "vg0" successfully created
从vg中取出lvm
[root@dream /]# lvcreate -L 100M -n lv0 vg0 ###从vg中取出100M建立lvm
Logical volume "lv0" created
格式化后挂载
[root@dream /]# mkfs.xfs /dev/vg0/lv0
meta-data=/dev/vg0/lv0 isize=256 agcount=4, agsize=6400 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=25600, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@dream /]# mount /dev/vg0/lv0 /mnt
[root@dream /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/vda1 10G 3.0G 7.1G 30% /
devtmpfs 459M 0 459M 0% /dev
tmpfs 474M 80K 474M 1% /dev/shm
tmpfs 474M 13M 462M 3% /run
tmpfs 474M 0 474M 0% /sys/fs/cgroup
/dev/mapper/vg0-lv0 97M 5.2M 92M 6% /mntLVM在线拉伸
1.当vg中的容量够用时
[root@dream /]# lvextend -L 500M /dev/vg0/lv0 ###扩展lvm的容量(直接从vg中取)拉伸到50M
Extending logical volume lv0 to 500.00 MiB
Logical volume lv0 successfully resized
[root@dream /]# xfs_growfs /dev/vg0/lv0 ###扩大文件系统xfs
meta-data=/dev/mapper/vg0-lv0 isize=256 agcount=4, agsize=6400 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=25600, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 25600 to 128000我们可以发现设备还在挂载中但却实现了拉伸
2.当vg中的容量不够用时
把vdb2转换成pv
[root@dream /]# pvcreate /dev/vdb2
WARNING: xfs signature detected on /dev/vdb2 at offset 0. Wipe it? [y/n] y
Wiping xfs signature on /dev/vdb2.
Physical volume "/dev/vdb2" successfully created
把vdb2加到vg0中
[root@dream /]# vgextend vg0 /dev/vdb2
Volume group "vg0" successfully extended可以发现vg0的容量变为了2G
拉伸到1.5G
[root@dream /]# lvextend -L 1.5G /dev/vg0/lv0
Extending logical volume lv0 to 1.50 GiB
Logical volume lv0 successfully resized
[root@dream /]# xfs_growfs /dev/vg0/lv0
meta-data=/dev/mapper/vg0-lv0 isize=256 agcount=20, agsize=6400 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=128000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 128000 to 393216
LVM的在线拉伸便说完了，但它有个缺陷并不能在线缩小，如果想可以缩小，可以把其格式化为ext4格式，但这中并不支持在线拉伸
ext4文件系统中拉伸
[root@dream /]# umount /mnt/
[root@dream /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/vda1 10G 3.0G 7.1G 30% /
devtmpfs 459M 0 459M 0% /dev
tmpfs 474M 80K 474M 1% /dev/shm
tmpfs 474M 13M 462M 3% /run
tmpfs 474M 0 474M 0% /sys/fs/cgroup
[root@dream /]# mkfs.ext4 /dev/vg0/lv0 ###格式化为ext4格式拉伸到1.8G
root@dream /]# lvextend -L 1.8G /dev/vg0/lv0
Rounding size to boundary between physical extents: 1.80 GiB
Extending logical volume lv0 to 1.80 GiB
Logical volume lv0 successfully resized
[root@dream /]# resize2fs /dev/vg0/lv0 1.8G
resize2fs 1.42.9 (28-Dec-2013)
resize2fs: Invalid new size: 1.8G
缩小到1G
[root@dream /]# e2fsck -f /dev/vg0/lv0 ###扫描数据大小，预防造成数据损失
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/vg0/lv0: 11/98304 files (9.1% non-contiguous), 15524/393216 blocks
[root@dream /]# resize2fs /dev/vg0/lv0 1G ###减小文件系统
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg0/lv0 to 262144 (4k) blocks.
The filesystem on /dev/vg0/lv0 is now 262144 blocks long.
[root@dream /]# lvreduce -L 1G /dev/vg0/lv0 ###减小设备大小
WARNING: Reducing active logical volume to 1.00 GiB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv0? [y/n]: y
Reducing logical volume lv0 to 1.00 GiB
Logical volume lv0 successfully resized可以发现大小变为了1G
正在使用的设备如何移出：
pvmove /dev/vdb1 /dev/vdb2 ###把/dev/vdb1数据拷贝到vdb2
vgreduce westos /dev/vdb1 ###把/dev/vdb1从westos中移出来
pvremove /dev/vdb1 ###移出设备（未使用的直接这一步就好）LVM快照
[root@dream /]# mount /dev/vg0/lv0 /mnt
[root@dream /]# cd /mnt
[root@dream mnt]# ls
lost+found
[root@dream mnt]# touch file{1..10}
[root@dream mnt]# ls
file1 file2 file4 file6 file8 lost+found
file10 file3 file5 file7 file9
[root@dream /]# lvcreate -L 10M -n lv0-backup -s /dev/vg0/lv0 ###创建快照
Logical volume "lv0-backup" created
[root@dream /]# mount /dev/vg0/lv0-backup /mnt
[root@dream /]# ls /mnt
file1 file2 file4 file6 file8 lost+found
file10 file3 file5 file7 file9
[root@dream /]# rm -rf /mnt/*
[root@dream /]# umount /dev/vg0/lv0-backup
[root@dream /]# lvcreate -L 10M -n lv0-backup -s /dev/vg0/lv0
mount /dev/vg0/lv0-backup /mnt/
ls /mntlvm的删除
lvremove /dev/vg0/lv0
vgremove vg0
pvremove /dev/vdb1
fdisk /dev/vdblvm挂载着的设备直接在fdisk中删除出现问题：
vgreduce --removemissing vg0