LVM 详解
大纲
一、简介
二、版本
三、LVM 模块
四、具体操作
对添加的硬盘进行分区(fdisk /dev/[hs]d[a-z])
对创建的分区创建物理卷(pvcreate)
给逻辑卷创建逻辑容器(卷组）
在卷组创建大小不同的逻辑卷(lvcreate)
给以存在的卷组扩大容量
实现在线扩大LVM容量
实现缩减LVM容量(不支持在线缩减)
减小卷组容量
利用给LVM创建快照，并完成备份并还原数据
一、简介
LVM是 Logical Volume Manager（逻辑卷管理）的简写，它是Linux环境下对磁盘分区进行管理的一种机制，它由Heinz Mauelshagen在Linux 2.4内核上实现，于1998年发布到Linux社区中，它允许你在Linux系统上用简单的命令行管理一个完整的逻辑卷管理环境。
二、版本
LVM1 最初的LVM与1998年发布，只在Linux内核2.4版本上可用，它提供最基本的逻辑卷管理。
LVM2 LVM-1的更新版本，在Linux内核2.6中才可用，它在标准的LVM-1功能外还提供了额外的功能。
查看：（测试机CentOS 5.5 X86_64）
[[email protected] ~]# uname -a Linux localhost.localdomain 2.6.18-194.el5 #1 SMP Fri Apr 2 14:58:14 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux [[email protected]lhost ~]# uname -r 2.6.18-194.el5 [[email protected] ~]# rpm -qa | grep lvm lvm2-2.02.56-8.el5 [[email protected] ~]#
三、LVM 模块
Physical volume (PV)、Volume group (VG)、Logical volume(LV)、 Physical extent (PE)，下面我们用一个简单的图来说明下物理卷、卷组、逻辑卷他们之间的关系(此图只是个人理解，仅供参考)
简而言之：
逻辑卷的创建，就是将多块硬盘创建物理卷，而将这些物理卷以逻辑的形式总成一个容器，然后从这个容器里面创建大小不同的分区文件，而这个容器就是所谓的逻辑卷，而从这个容器里创建大小不同的分区文件，这个分区文件就叫做逻辑卷。嘿嘿，你懂了吗？ ^_^ ……
四、具体操作
1. 分区
[[email protected] ~]# fdisk –l #查看已存在的分区与硬盘 Disk /dev/sda: 21.4 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 33 265041 83 Linux /dev/sda2 34 1308 10241437+ 83 Linux /dev/sda3 1309 1945 5116702+ 83 Linux /dev/sda4 1946 2610 5341612+ 5 Extended /dev/sda5 1946 2072 1020096 82 Linux swap / Solaris Disk /dev/sdb: 21.4 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk /dev/sdb doesn't contain a valid partition table Disk /dev/sdc: 21.4 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk /dev/sdc doesn't contain a valid partition table [[email protected] ~]# fdisk /dev/sdb #给/sdb分区,效果如下 Command (m for help): p Disk /dev/sdb: 21.4 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 244 1959898+ 8e Linux LVM #注意修改分区类型为8e /dev/sdb2 245 488 1959930 8e Linux LVM /dev/sdb3 489 732 1959930 8e Linux LVM Command (m for help): [[email protected] ~]# partprobe #让内核重新读取一下硬盘 [[email protected] ~]# fdisk -l /dev/sdb Disk /dev/sdb: 21.4 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 244 1959898+ 8e Linux LVM /dev/sdb2 245 488 1959930 8e Linux LVM /dev/sdb3 489 732 1959930 8e Linux LVM [[email protected] ~]#2. 将物理分区与硬盘创建为物理卷(pvcreate)
[[email protected] ~]# pvcreate /dev/sdb[1-3] #将分区创建为物理卷 Physical volume "/dev/sdb1" successfully created Physical volume "/dev/sdb2" successfully created Physical volume "/dev/sdb3" successfully created [[email protected] ~]# [[email protected] ~]# pvcreate /dev/sdc #将硬盘创建为物理卷 Physical volume "/dev/sdc" successfully created [[email protected] ~]# pvs #查看创建的物理卷 PV VG Fmt Attr PSize PFree /dev/sdb1 myvg lvm2 a- 1.87G 1.87G /dev/sdb2 myvg lvm2 a- 1.87G 1.87G /dev/sdb3 myvg lvm2 a- 1.87G 1.87G /dev/sdc myvg lvm2 a- 20.00G 20.00G3. 将物理卷(pv)创建为卷组(vgcreate)，名为myvg
[[email protected] ~]# vgcreate myvg /dev/sdb[1-3] /dev/sdc Volume group "myvg" successfully created [[email protected] ~]# vgs VG #PV #LV #SN Attr VSize VFree myvg 4 0 0 wz--n- 25.60G 25.60G [[email protected] ~]# [[email protected] ~]# vgdisplay --- Volume group --- VG Name myvg #卷组名 System ID Format lvm2 Metadata Areas 4 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 4 Act PV 4 VG Size 25.60 GB PE Size 4.00 MB #物理盘的基本单位：默认4MB Total PE 6553 Alloc PE / Size 0 / 0 Free PE / Size 6553 / 25.60 GB VG UUID wuNBgb-tP95-pVoX-ehHw-cMfN-hyem-PNMqwe [[email protected] ~]#4. 在卷组里创建逻辑卷并格式化、挂载使用
[[email protected] ~]# lvcreate -L 2G -n mylv1 myvg #创建逻辑卷 Logical volume "mylv1" created [[email protected] ~]# lvs #查看逻辑卷 LV VG Attr LSize Origin Snap% Move Log Copy% Convert mylv1 myvg -wi-a- 2.00G [[email protected] ~]# mke2fs -j /dev/myvg/mylv1 #格式化逻辑卷 mke2fs 1.39 (29-May-2006) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 262144 inodes, 524288 blocks 26214 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=536870912 16 block groups 32768 blocks per group, 32768 fragments per group 16384 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912 Writing inode tables: done Creating journal (16384 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 26 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [[email protected] ~]# mkdir /mydata #创建挂载目录 [[email protected] ~]# mount /dev/myvg/mylv1 /mydata/ #挂载 [[email protected] ~]# mount #查看是否挂载成功 /dev/sda2 on / type ext3 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) /dev/sda3 on /data type ext3 (rw) /dev/sda1 on /boot type ext3 (rw) tmpfs on /dev/shm type tmpfs (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw) /dev/mapper/myvg-mylv1 on /mydata type ext3 (rw) [[email protected] ~]# [[email protected] ~]# ls /mydata/ #查看 lost+found [[email protected] ~]# df –h #查看硬盘 Filesystem Size Used Avail Use% Mounted on /dev/sda2 9.5G 1.8G 7.2G 20% / /dev/sda3 4.8G 138M 4.4G 4% /data /dev/sda1 251M 17M 222M 7% /boot tmpfs 60M 0 60M 0% /dev/shm /dev/mapper/myvg-mylv1 2.0G 68M 1.9G 4% /mydata [[email protected] ~]#5. 发现卷组空间不够，我们扩大卷组空间
[[email protected] ~]# pvcreate /dev/sdd #将新硬盘/sdd加入物理卷中 Physical volume "/dev/sdd" successfully created [[email protected] ~]# pvs #查看物理卷 /dev/cdrom: open failed: No medium found PV VG Fmt Attr PSize PFree /dev/sdb1 myvg lvm2 a- 1.87G 1.87G /dev/sdb2 myvg lvm2 a- 1.87G 1.87G /dev/sdb3 myvg lvm2 a- 1.87G 1.87G /dev/sdc myvg lvm2 a- 20.00G 18.00G /dev/sdd myvg lvm2 a- 20.00G 20.00G [[email protected] ~]# [[email protected] ~]# vgextend myvg /dev/sdd #扩展卷组 Volume group "myvg" successfully extended [[email protected] ~]# vgs #查看新增加的卷组 VG #PV #LV #SN Attr VSize VFree myvg 5 1 0 wz--n- 45.59G 43.59G [[email protected] ~]#6. 扩展逻辑卷 (支持在线扩展)
将/dev/myvg/mylv1 扩展到4G，并且要求数据可以正常访问 [[email protected] ~]# cd /mydata/ [[email protected] mydata]# touch index.html [[email protected] mydata]# echo "test" > index.html [[email protected] mydata]# cat index.html test [[email protected] mydata]# vgs /dev/cdrom: open failed: No medium found VG #PV #LV #SN Attr VSize VFree myvg 5 1 0 wz--n- 45.59G 43.59G [[email protected] mydata]# lvextend -L +2G /dev/myvg/mylv1 Extending logical volume mylv1 to 4.00 GB Logical volume mylv1 successfully resized [[email protected] mydata]# resize2fs -p /dev/myvg/mylv1 #通过 resize2fs 将文件系统的容量确实添加 resize2fs 1.39 (29-May-2006) Filesystem at /dev/myvg/mylv1 is mounted on /mydata; on-line resizing required Performing an on-line resize of /dev/myvg/mylv1 to 1048576 (4k) blocks. The filesystem on /dev/myvg/mylv1 is now 1048576 blocks long. [[email protected] mydata]# lvs LV VG Attr LSize Origin Snap% Move Log Copy% Convert mylv1 myvg -wi-ao 4.00G [[email protected] mydata]# [[email protected] mydata]# cat index.html test [[email protected] mydata]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 9.5G 1.8G 7.2G 20% / /dev/sda3 4.8G 138M 4.4G 4% /data /dev/sda1 251M 17M 222M 7% /boot tmpfs 60M 0 60M 0% /dev/shm /dev/mapper/myvg-mylv1 4.0G 69M 3.7G 2% /mydata #成功增加了2G [[email protected] mydata]#7. 缩减逻辑卷
查看逻辑卷使用空间状况
不能在线缩减，得先卸载
确保缩减后的空间大小依然能存储原有的所有数据
在缩减之前应该先强行检查文件，以确保文件系统处于一至性状态
将/dev/myvg/mylv1 缩减到1G，并且要求数据可以正常访问 (所以我们就按上面的提示在操作） [[email protected] ~]#df –lh #查看已用空间大小 [[email protected] ~]# umount /dev/myvg/mylv1 #卸载分区 [[email protected] ~]# e2fsck -f /dev/myvg/mylv1 #强制检查文件系统 [[email protected] ~]# resize2fs /dev/myvg/mylv1 1G #缩减逻辑大小 [[email protected] ~]# lvreduce -L 1G /dev/myvg/mylv1 #缩减物理边界大小 [[email protected] ~]# lvs #查看逻辑卷 /dev/cdrom: open failed: No medium found LV VG Attr LSize Origin Snap% Move Log Copy% Convert mylv1 myvg -wi-ao 1.00G [[email protected] ~]# mount /dev/myvg/mylv1 /mydata [[email protected] ~]# ls /mydata/ index.html lost+found [[email protected] ~]# cat /mydata/index.html test [[email protected] ~]#8. 缩减磁盘空间
发现物理磁盘空间使用不足，将其中一块硬盘或分区拿掉
pvmove /dev/sdb1 #将/dev/sdb1上存储的数据移到其它物理卷中
vgreduce myvg /dev/sdb1 #将/dev/sdb1从myvg卷组中移除
pvremove /dev/sdb1 #将/dev/sdb1从物理卷上移除
[[email protected] ~]# pvs /dev/cdrom: open failed: No medium found PV VG Fmt Attr PSize PFree /dev/sdb1 myvg lvm2 a- 1.87G 1.87G /dev/sdb2 myvg lvm2 a- 1.87G 1.87G /dev/sdb3 myvg lvm2 a- 1.87G 1.87G /dev/sdc myvg lvm2 a- 20.00G 19.00G /dev/sdd myvg lvm2 a- 20.00G 20.00G [[email protected] ~]# [[email protected] ~]# pvmove /dev/sdb1 No data to move for myvg [[email protected] ~]# vgreduce myvg /dev/sdb1 Removed "/dev/sdb1" from volume group "myvg" [email protected] ~]# pvremove /dev/sdb1 Labels on physical volume "/dev/sdb1" successfully wiped [[email protected] ~]# pvs /dev/cdrom: open failed: No medium found PV VG Fmt Attr PSize PFree /dev/sdb2 myvg lvm2 a- 1.87G 1.87G /dev/sdb3 myvg lvm2 a- 1.87G 1.87G /dev/sdc myvg lvm2 a- 20.00G 19.00G /dev/sdd myvg lvm2 a- 20.00G 20.00G [[email protected] ~]#9. 实现快照，进行备份还原
在/mnt/lvm目录上，我们将原始的目录文件进行快照，然后将/mydata目录中的内容清空，并进行还原
[[email protected] ~]# cd /mydata/ [[email protected] mydata]# ls index.html lost+found [[email protected] mydata]# cat index.html test [[email protected] mydata]# lvcreate -L 30M -n backup -s -p r /dev/myvg/mylv1 #-L 快照大小 –n:快照名称 –p 权限只读 –s 创建快照 Rounding up size to full physical extent 32.00 MB Logical volume "backup" created [[email protected] mydata]# ll total 20 -rw-r--r-- 1 root root 5 Jun 28 01:04 index.html drwx------ 2 root root 16384 Jun 28 00:47 lost+found [[email protected] mydata]# mkdir /tmp/backup #创建挂载目录 [[email protected] mydata]# mount /dev/myvg/backup /tmp/backup/ #挂载 mount: block device /dev/myvg/backup is write-protected, mounting read-only [[email protected] mydata]# cd /tmp/backup/ [[email protected] backup]# ls index.html lost+found [[email protected] backup]# mkdir /tmp/lvmbackup #创建备份目录 [[email protected] backup]# tar jcf /tmp/lvmbackup/sandy.tar.bz2 index.html #打包并压缩文件 [[email protected] backup]# cd .. [[email protected] tmp]# cd lvmbackup/ [[email protected] lvmbackup]# ls #查看备份 sandy.tar.bz2 [[email protected] lvmbackup]# cd /mydata/ [[email protected] mydata]# ll total 20 -rw-r--r-- 1 root root 5 Jun 28 01:04 index.html drwx------ 2 root root 16384 Jun 28 00:47 lost+found [[email protected] mydata]# rm -rf * #删除所有文件 [[email protected] mydata]# [[email protected] mydata]# ll total 0 [[email protected] mydata]# tar xf /tmp/lvmbackup/sandy.tar.bz2 #还原备份数据 [[email protected] mydata]# ll total 4 -rw-r--r-- 1 root root 5 Jun 28 01:04 index.html [[email protected] mydata]# cat index.html test [[email protected] mydata]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 9.5G 1.8G 7.2G 21% / /dev/sda3 4.8G 138M 4.4G 4% /data /dev/sda1 251M 17M 222M 7% /boot tmpfs 60M 0 60M 0% /dev/shm /dev/mapper/myvg-mylv1 1008M 67M 901M 7% /mydata /dev/mapper/myvg-mylv1 1008M 67M 901M 7% /tmp/backup [[email protected] mydata]#了解以上步骤操作的含义，我相信大家应该对LVM有更深的认识，嘿嘿 ^_^……
转载于:https://blog.51cto.com/freeloda/1231089