lvm分区
试验环境 centos 6.5
借图如下
一、LVM原理
传统文件系统，比如这个盘只有300G，那么建立在这个300G上面的文件系统最多只能用到300G，但是有了LVM这个功能后，我们建立文件系统的盘就不是建立在物理盘上，而是建立在一个叫LV逻辑卷上面，这个卷是一个逻辑概念不是物理盘，空间可能大于一个物理盘，也可能小于一个物理盘。而且这个LV逻辑卷的空间可以扩展和缩小，这样就给上层的文件系统提供了更好的支持。
需要理解的几个概念：
PV（Physical Volume）：物理空间的意思，其实就是指一个分区（如/dev/sdb1 ）或者是一个盘（如/dev/sdb）
VG（Volume Group）：相当于一个Pool，由多个PV组成的pool
LV（Logical Volume）：用来建立一个文件系统的空间，这个空间来源于VG，大小随意，可以扩展。(比如/dev/mapper/rhel-root这个目录其实是一个文件系统挂载点，这个点就是承载在一个LV上，这个文件系统的大小就是这个LV的大小。 )
二、实际操作
1、使用fdisk -l查看磁盘情况，可以看到我有两块未分区的磁盘，分别是/dev/sdb /dev/sdc，我们先用一块磁盘/dev/sdb进行测试。
[root@test_iptables ~]# fdisk -l Disk /dev/sdb: 1073 MB, 1073741824 bytes 255 heads, 63 sectors/track, 130 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sda: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0005b552 Device Boot Start End Blocks Id System /dev/sda1 * 1 39 307200 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 39 2350 18566144 83 Linux /dev/sda3 2350 2611 2097152 82 Linux swap / Solaris Disk /dev/sdc: 1073 MB, 1073741824 bytes 255 heads, 63 sectors/track, 130 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000
2、对/dev/sdb进行分区
（1）先进行标准分区
[root@test_iptables ~]# fdisk /dev/sdb Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel with disk identifier 0x34c351e7. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). 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): Using default value 130 Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
（2）查看使用vgdisplay查看已经存在的卷组名称
[root@test_iptables ~]# vgdisplay
No volume groups found
（3）开始进行lvm处理
创建物理卷（PV）
[root@test_iptables ~]# pvcreate /dev/sdb1 dev_is_mpath: failed to get device for 8:17 Physical volume "/dev/sdb1" successfully created
创建卷组（VG）
[root@test_iptables ~]# vgcreate vg01 /dev/sdb1 Volume group "vg01" successfully created
查看创建的物理卷及卷组
在卷组vg01上创建名为date，大小为1000M的逻辑卷
[root@test_iptables ~]# lvcreate -L 1000M -n data vg01 Logical volume "data" created
或者使用
lvcreate -L 100%FREE -n data vg01---貌似报错，如何使用全部容量？
3、格式化分区
[root@test_iptables ~]# mkfs.ext4 /dev/vg01/data 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 64000 inodes, 256000 blocks 12800 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=264241152 8 block groups 32768 blocks per group, 32768 fragments per group 8000 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376 Writing inode tables: done Creating journal (4096 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 33 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
4、挂载分区
[root@test_iptables ~]# mkdir /u01 [root@test_iptables ~]# mount /dev/vg01/data /u01/ [root@test_iptables ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 18G 9.2G 7.4G 56% / tmpfs 931M 72K 931M 1% /dev/shm /dev/sda1 291M 39M 238M 14% /boot /dev/vg01/data 985M 18M 918M 2% /u01
5、设置开机自动挂载
[root@test_iptables ~]# cat /etc/fstab # # /etc/fstab # Created by anaconda on Wed Sep 11 09:19:25 2019 # # 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 # UUID=fe5d2642-dc89-45a2-963a-2a5e0f7e5a3a / ext4 defaults 1 1 UUID=e356222c-cde8-4f30-a38c-3fcf905b65c8 /boot ext4 defaults 1 2 UUID=4d5bbee9-6557-4b6b-a275-4c43b14dce9d swap swap defaults 0 0 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 /dev/vg01/data /u01 ext4 defaults 0 0
至此，一个lvm分区设置完毕
三、PV扩容
1、首先进行标准分区
root@test_iptables ~]# fdisk /dev/sdc Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel with disk identifier 0x114bf00d. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). 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): Using default value 130 Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
2、创建物理卷
[root@test_iptables ~]# pvcreate /dev/sdc1 Physical volume "/dev/sdc1" successfully created
3、VG扩容
将新的物理卷加入卷组
[root@test_iptables ~]# vgextend vg01 /dev/sdc1 Volume group "vg01" successfully extended
扩展逻辑卷 并resize2fs加载逻辑卷
[root@test_iptables ~]# lvextend -l +100%FREE /dev/vg01/data Extending logical volume data to 1.98 GiB Logical volume data successfully resized [root@test_iptables ~]# resize2fs /dev/vg01/data resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/vg01/data is mounted on /u01; on-line resizing required old desc_blocks = 1, new_desc_blocks = 1 Performing an on-line resize of /dev/vg01/data to 520192 (4k) blocks. The filesystem on /dev/vg01/data is now 520192 blocks long.
注意：如果这个文件是xfs格式的，需要使用xfs_growfs命令，可以cat /etc/fstab查看文件系统类型或者df -T -h
例如：
resize2fs /dev/mapper/centos-root需要修改成
xfs_growfs /dev/mapper/centos-root
如果挂载出现以下报错xfs_growfs: /dev/cl/root is not a mounted XFS filesystem，直接跟挂载点
重新加载后，再输入df -h即可看到空间已扩展
至此，以上就是整个流程，成功扩展为2G。
