centos 磁盘管理（lvm模式）
这种磁盘管理方式相对于标准模式的优势在于，它可以动态的改变磁盘大小。
步骤：
1）要有一个物理磁盘或者是多个没有被格式化的分区（physical volume—pv）
2）多个物理卷组合成一个卷组（volume group）
3）重卷组中划分出逻辑卷（logic volume）
下面开始以lvm模式多Linux磁盘进行管理：
首先要先安装lvm包
yum install -y lvm2
安装好了后，开始划分物理卷，我这里采用的是多个为被格式化的标准分区。
[root@weijie ~]# pvcreate /dev/sdb5
[root@weijie ~]# pvdisplay
"/dev/sdb2" is a new physical volume of "1.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb2
VG Name
PV Size 1.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID w3EdeD-JV3e-uFXb-eQ4R-eA7P-91aj-3MvjWU
"/dev/sdb5" is a new physical volume of "1.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb5
VG Name
PV Size 1.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID M84fIM-PItt-tDGe-HYzj-5VQw-sjGh-4j0mDb
"/dev/sdb3" is a new physical volume of "2.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb3
VG Name
PV Size 2.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID GWOCoq-I8QU-Yzjt-tx7O-qPTA-idVc-16xpoL
可以看到我这里划分出了3个pv。
下面把这3个pv划分到一个卷组中：
[root@weijie ~]# vgcreate vg1 /dev/sdb3 /dev/sdb2 /dev/sdb5
Volume group "vg1" successfully created
[root@weijie ~]# ls
anaconda-ks.cfg
[root@weijie ~]# vgdisplay
--- Volume group ---
VG Name vg1
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 <3.99 GiB
PE Size 4.00 MiB
Total PE 1021
Alloc PE / Size 0 / 0
Free PE / Size 1021 / <3.99 GiB
VG UUID 4Oq7ZJ-ijut-5Ecz-6V9M-S0t4-qajD-S01GVy
创建好了vg，并查看。
然后开始划分逻辑卷，之后就可以挂载了：
[root@weijie ~]# lvcreate -L 500M -n lv1 vg1
Logical volume "lv1" created.
-L 指定逻辑卷的大小
-n 指定逻辑卷的名字
最后对这个逻辑分区进行格式化，挂载。
[root@weijie ~]# mkfs.xfs /dev/vg1/lv1 //格式化这个逻辑卷
meta-data=/dev/vg1/lv1 isize=512 agcount=4, agsize=32000 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=128000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=855, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@weijie ~]# mount /dev/vg1/lv1 /home/lala
[root@weijie ~]# df -h //查看下磁盘挂载情况
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 14G 1.8G 13G 13% /
devtmpfs 479M 0 479M 0% /dev
tmpfs 489M 0 489M 0% /dev/shm
tmpfs 489M 6.8M 482M 2% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/mapper/vg1-lv1 497M 26M 472M 6% /home/lala //可以看到lv1已经被挂载
/dev/sda1 473M 111M 362M 24% /boot
tmpfs 98M 0 98M 0% /run/user/0
好下面就是体现lvm磁盘管理的优势的地方了。
假如我lv1磁盘空间不够用了，我就需要对它进行扩容，如果是标准分区的话，你需要先分区，然后格式化，然后再挂载，很麻烦。而在lvm模式下，我们只需对逻辑卷（lv1）进行修改就可以了。
[root@weijie ~]# lvdisplay
--- Logical volume ---
LV Path /dev/vg1/lv1
LV Name lv1
VG Name vg1
LV UUID 7EpNbn-BZoq-yZ23-ZMxq-kPaY-aQYx-wQRO5o
LV Write Access read/write
LV Creation host, time weijie, 2020-02-29 14:12:32 +0800
LV Status available
# open 1
LV Size 500.00 MiB //没有扩容前是500M
Current LE 125
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@weijie ~]# lvresize -L 800M /dev/vg1/lv1 //我想把lv1扩容到800M
Size of logical volume vg1/lv1 changed from 500.00 MiB (125 extents) to 800.00 MiB (200 extents).
Logical volume vg1/lv1 successfully resized.
[root@weijie ~]# lvdisplay
--- Logical volume ---
LV Path /dev/vg1/lv1
LV Name lv1
VG Name vg1
LV UUID 7EpNbn-BZoq-yZ23-ZMxq-kPaY-aQYx-wQRO5o
LV Write Access read/write
LV Creation host, time weijie, 2020-02-29 14:12:32 +0800
LV Status available
# open 1
LV Size 800.00 MiB //经过修改后变为800M
Current LE 200
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
但是！！！！！！！！！！！！
[root@weijie ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 14G 1.8G 13G 13% /
devtmpfs 479M 0 479M 0% /dev
tmpfs 489M 0 489M 0% /dev/shm
tmpfs 489M 6.7M 482M 2% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/mapper/vg1-lv1 497M 26M 472M 6% /home/lala
/dev/sda1 473M 111M 362M 24% /boot
tmpfs 98M 0 98M 0% /run/user/0
从这里查看还是只有500M 实际上lv1已经变成了800M 只是没有多磁块信息进行更新。
[root@weijie test]# xfs_growfs /dev/vg1/lv1
meta-data=/dev/mapper/vg1-lv1 isize=512 agcount=4, agsize=32000 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=128000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=855, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 128000 to 204800
这样在线更新后，在查看磁盘分配情况。
[root@weijie test]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 14G 1.8G 13G 13% /
devtmpfs 479M 0 479M 0% /dev
tmpfs 489M 0 489M 0% /dev/shm
tmpfs 489M 6.7M 482M 2% /run
tmpfs 489M 0 489M 0% /sys/fs/cgroup
/dev/sdb1 2.0G 33M 2.0G 2% /home/lala
/dev/sda1 473M 111M 362M 24% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 797M 26M 772M 4% /test
这里可以看到成功的变成了800M了
你以为这就结束了？？不不不，lvm模式的动态扩容不仅可以扩逻辑卷，还可以扩卷组。
我们重新在创建一个物理卷，然后把它划入卷组
[root@weijie /]# pvcreate /dev/sdb6
Physical volume "/dev/sdb6" successfully created.
[root@weijie /]# vgextend vg1 /dev/sdb6
Volume group "vg1" successfully extended
[root@weijie /]# vgdisplay
--- Volume group ---
VG Name vg1
System ID
Format lvm2
Metadata Areas 4
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 4
Act PV 4
VG Size 5.98 GiB
PE Size 4.00 MiB
Total PE 1532
Alloc PE / Size 200 / 800.00 MiB
Free PE / Size 1332 / 5.20 GiB
VG UUID 4Oq7ZJ-ijut-5Ecz-6V9M-S0t4-qajD-S01GVy
这里就可以看到卷组已经扩大了