1.LVM的基本简介
LVM：logical Volume Manager，逻辑卷管理，其目的在于可以弹性调整文件系统容量。LVM建立在硬盘和分区之上的一个逻辑层，来提高磁盘分区管理的灵活性，它可以整合多个物理分区在一起，让这些分区看起来像一个磁盘，而且，还可以将其他物理分区添加LVM中或从这个LVM管理的磁盘中删除。
2.LVM基本术语
PV：Physical Volume物理卷，就是指硬盘分区或从逻辑上与磁盘分区具有同样功能的设备(如RAID)，是LVM的基本存储逻辑块，但和基本的物理存储介质（如分区、磁盘等）比较，却包含有与LVM相关的管理参数。注意：需要将分区标识符改为8e（LVM的标识符），然后用pvcreate
命令创建pv。
VG：Volume Group卷组类似于非LVM系统中的物理硬盘，其由物理卷组成。可以在卷组上创建一个或多个“LVM分区”（逻辑卷），LVM卷组由一个或多个物理卷组成。
PE：每一个物理卷被划分为称为PE(Physical Extents)的基本单元，具有唯一编号的PE是可以被LVM寻址的最小单元。PE的大小是可配置的，默认为4MB。
LV：从VG中划分的逻辑分区。
3.LVM的创建与管理
创建分区：使用fdisk命令创建分区，调整分区标识符为8e。
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[[email protected] ~]# fdisk /dev/sda 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 l logical (5 or over) p primary partition (1-4) l First cylinder (7859-15665, default 7859): Using default value 7859 Last cylinder, +cylinders or +size{K,M,G} (7859-15665, default 15665): +5G Command (m for help): n Command action l logical (5 or over) p primary partition (1-4) l First cylinder (8513-15665, default 8513): Using default value 8513 Last cylinder, +cylinders or +size{K,M,G} (8513-15665, default 15665): +5G Command (m for help): P Disk /dev/sda: 128.8 GB, 128849018880 bytes 255 heads, 63 sectors/track, 15665 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: 0x00051a06 Device Boot Start End Blocks Id System /dev/sda1 * 1 26 204800 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 26 7859 62914560 8e Linux LVM /dev/sda3 7859 15665 62708728+ 5 Extended /dev/sda5 7859 8512 5252224+ 83 Linux /dev/sda6 8513 9166 5253223+ 83 Linux Command (m for help): t Partition number (1-6): 5 Hex code (type L to list codes): 8e Changed system type of partition 5 to 8e (Linux LVM) Command (m for help): t Partition number (1-6): 6 Hex code (type L to list codes): 8e Changed system type of partition 6 to 8e (Linux LVM) Command (m for help): p Disk /dev/sda: 128.8 GB, 128849018880 bytes 255 heads, 63 sectors/track, 15665 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: 0x00051a06 Device Boot Start End Blocks Id System /dev/sda1 * 1 26 204800 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 26 7859 62914560 8e Linux LVM /dev/sda3 7859 15665 62708728+ 5 Extended /dev/sda5 7859 8512 5252224+ 8e Linux LVM /dev/sda6 8513 9166 5253223+ 8e Linux LVM |
创建PV：pvcreate /dev/devices，使用pvdisplay查看pv详细信息。
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[[email protected] ~]# pvcreate /dev/sda5 /dev/sda6 Physical volume "/dev/sda5" successfully created Physical volume "/dev/sda6" successfully created [[email protected] ~]# pvdisplay /dev/sda5 /dev/sda6 "/dev/sda5" is a new physical volume of "5.01 GiB" --- NEW Physical volume --- PV Name /dev/sda5 VG Name PV Size 5.01 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID L8WHe3-EdsZ-aC6K-RJUW-8kkL-D8wj-RiwkUv "/dev/sda6" is a new physical volume of "5.01 GiB" --- NEW Physical volume --- PV Name /dev/sda6 VG Name PV Size 5.01 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID EcvE1Y-5wXl-t5Kc-M48F-Nrqw-R2hL-xi0hch |
创建VG：vgcreate VolumeGroupName PhysicalDevicePath
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[[email protected] ~]# vgcreate myvg /dev/sda5 /dev/sda6 Volume group "myvg" successfully created [[email protected] ~]# vgdisplay myvg --- Volume group --- VG Name myvg System ID Format lvm2 Metadata Areas 2 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 2 Act PV 2 VG Size 10.02 GiB PE Size 4.00 MiB Total PE 2564 Alloc PE / Size 0 / 0 Free PE / Size 2564 / 10.02 GiB VG UUID mDpNg3-cUa0-AQ2F-doM2-9wmj-fc6t-Q2XqiH |
创建LV：lvcreate -L #[mMgGtT] -n NAME VolumeGroup
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[[email protected] ~]# lvcreate -L 10 -n mylv myvg Rounding up size to full physical extent 12.00 MiB Logical volume "mylv" created [[email protected] ~]# lvdisplay /dev/myvg/mylv --- Logical volume --- LV Path /dev/myvg/mylv LV Name mylv VG Name myvg LV UUID yfJqxR-ao9l-uR9p-OcEb-Xdi4-pJ2d-7bYO5A LV Write Access read/write LV Creation host, time magedu, 2015-08-18 13:21:49 +0800 LV Status available # open 0 LV Size 12.00 MiB Current LE 3 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:4 |
LV格式化及挂载：lv需要先格式化才能存储
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[[email protected] ~]# mke2fs -t ext4 /dev/myvg/mylv mke2fs 1.41.12 (17-May-2010) Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) Stride=0 blocks, Stripe width=0 blocks 3072 inodes, 12288 blocks 614 blocks (5.00%) reserved for the super user First data block=1 Maximum filesystem blocks=12582912 2 block groups 8192 blocks per group, 8192 fragments per group 1536 inodes per group Superblock backups stored on blocks: 8193 Writing inode tables: done Creating journal (1024 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 32 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [[email protected] ~]# mkdir /tmp/lvtest [[email protected] ~]# mount /dev/myvg/mylv /tmp/lvtest/ [[email protected] ~]# mount /dev/mapper/vg0-root 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) /dev/mapper/vg0-usr on /usr type ext4 (rw) /dev/mapper/vg0-var on /var type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) /dev/mapper/myvg-mylv on /tmp/lvtest type ext4 (rw) |
扩展逻辑卷：
lvextend -L [+]#[mMgGtT] /dev/VG_NAME/LV_NAME
resize2fs /dev/VG_NAME/LV_NAME
缩减逻辑卷：
umount /dev/VG_NAME/LV_NAME
e2fsck -f /dev/VG_NAME/LV_NAME
resize2fs /dev/VG_NAME/LV_NAME #[mMgGtT]
lvreduce -L [-]#[mMgGtT] /dev/VG_NAME/LV_NAME
mount