LVM(Logic Volume Management,逻辑卷管理
由多个块设备(pv,卷)组成一个逻辑卷组(vg)，接着在逻辑组上创建逻辑卷(lv)，实现在线缩减逻辑卷与逻辑卷组。
实验：
1、VM虚拟机添加硬盘：
2G(/dev/sdb)
3G(/dev/sdc)
5G(/dev/sdd)
2、查看硬盘信息：
[root@neolinux ~]# fdisk -l | grep -e "^Disk /dev/sd[b-d]" Disk /dev/sdb: 2147 MB, 2147483648 bytes Disk /dev/sdc: 3221 MB, 3221225472 bytes Disk /dev/sdd: 5368 MB, 5368709120 bytes
3、将磁盘设定为PV，并且查看PV的信息：
[root@neolinux ~]# pvcreate /dev/sd[b-d] #将磁盘设置为PV Physical volume "/dev/sdb" successfully created Physical volume "/dev/sdc" successfully created Physical volume "/dev/sdd" successfully created [root@neolinux ~]# pvs #显示当前PV信息 PV VG Fmt Attr PSize PFree /dev/sda3 VG lvm2 a-- 17.80g 0 /dev/sdb lvm2 --- 2.00g 2.00g /dev/sdc lvm2 --- 3.00g 3.00g /dev/sdd lvm2 --- 5.00g 5.00g [root@neolinux ~]# pvdisplay /dev/sdb #显示PV详细信息 "/dev/sdb" is a new physical volume of "2.00 GiB" --- NEW Physical volume --- PV Name /dev/sdb VG Name PV Size 2.00 GiB Allocatable NO PE Size 0 #PE Size是在创建VG时指定 Total PE 0 #该磁盘一共有多少个PE，取决于创建VG时，指定PE的大小 Free PE 0 #该磁盘剩余可用PE数量 Allocated PE 0 PV UUID cu50Yp-PcWC-o76e-CTyK-CBgt-BjaJ-2z98lt #每一个PV的UUID都不一样 [root@neolinux ~]#
4、创建VG,并且查看VG的信息：
[root@neolinux ~]# vgcreate -s 16M myvg /dev/sd[b-d] #创建名字为myvg的逻辑卷组，添加/dev/sdb,/dev/sdc,/dev/sdd到此卷组中,指定PE大小为16M，默认为4M Volume group "myvg" successfully created [root@neolinux ~]# vgs VG #PV #LV #SN Attr VSize VFree VG 1 2 0 wz--n- 17.80g 0 myvg 3 0 0 wz--n- 9.95g 9.95g #此VG 一共有多少容量可使用 [root@neolinux ~]# vgdisplay myvg --- Volume group --- VG Name myvg 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 9.95 GiB PE Size 16.00 MiB #VG中PE大小 Total PE 637 Alloc PE / Size 0 / 0 Free PE / Size 637 / 9.95 GiB VG UUID DLTJNf-he5S-I8rw-jUNZ-8CK1-Cb3w-TqCMCD [root@neolinux ~]# pvdisplay /dev/sdb --- Physical volume --- PV Name /dev/sdb VG Name myvg #显示磁盘加入到myvg卷组中 PV Size 2.00 GiB / not usable 16.00 MiB Allocatable yes PE Size 16.00 MiB Total PE 127 Free PE 127 Allocated PE 0 PV UUID cu50Yp-PcWC-o76e-CTyK-CBgt-BjaJ-2z98lt
5、创建逻辑卷lv，并查看lv信息
[root@neolinux ~]# lvcreate -n mylv -L 6G -p rw myvg #创建lv Logical volume "mylv" created. #-n:指定lv名称 #-L:指定lv大小 #-p:指定读写权限 [root@neolinux ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert LV01 VG -wi-ao---- 9.77g LV02 VG -wi-ao---- 8.04g mylv myvg -wi-a----- 6.00g [root@neolinux ~]# lvdisplay /dev/myvg/mylv --- Logical volume --- LV Path /dev/myvg/mylv LV Name mylv VG Name myvg LV UUID Ob0WO9-CMn0-pVLu-xd5a-fy4g-ABDM-JGB8et LV Write Access read/write LV Creation host, time neolinux, 2016-06-04 02:29:09 +0800 LV Status available # open 0 LV Size 6.00 GiB Current LE 384 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2 [root@neolinux ~]#
6、格式化文件系统，挂载使用
[root@neolinux ~]# mke2fs -t ext4 /dev/myvg/mylv #格式化分区 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 393216 inodes, 1572864 blocks 78643 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=1610612736 48 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 34 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [root@neolinux ~]# mount /dev/myvg/mylv /mnt #挂载使用 [root@neolinux ~]# mount | grep /mnt /dev/mapper/myvg-mylv on /mnt type ext4 (rw) [root@neolinux ~]# df -Th /mnt/ Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/myvg-mylv ext4 5.8G 12M 5.5G 1% /mnt [root@neolinux ~]# cp /etc/rc.d/init.d/functions /mnt [root@neolinux ~]# ll /mnt/ total 44 -rw-r--r-- 1 root root 25419 Jun 4 02:55 functions drwx------ 2 root root 16384 Jun 4 02:51 lost+found [root@neolinux ~]#
7、在线扩展lv容量
[root@neolinux ~]# lvextend -L +1G /dev/myvg/mylv #+号表示在原有容量的基础上新增多少，不写+号表示容量扩容到多少，在扩展容量之前，应该提前检查该LV所在的VG上可用容量是否满足需求，在去扩展LV的逻辑边界 Size of logical volume myvg/mylv changed from 6.00 GiB (384 extents) to 7.00 GiB (448 extents). Logical volume mylv successfully resized [root@neolinux ~]# df -Th /mntFilesystem #查看挂载/mnt目录容量大小，没有发生变化，是因为没有扩展LV的逻辑边界 Type Size Used Avail Use% Mounted on/dev/mapper/myvg-mylv ext4 5.8G 13M 5.5G 1% /mnt [root@neolinux ~]# resize2fs /dev/myvg/mylv #扩展LV的逻辑边界，这里没有指定大小，表示与LV的物理边界一样大 resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/myvg/mylv is mounted on /mnt; on-line resizing required old desc_blocks = 1, new_desc_blocks = 1 Performing an on-line resize of /dev/myvg/mylv to 1835008 (4k) blocks. The filesystem on /dev/myvg/mylv is now 1835008 blocks long. [root@neolinux ~]# df -Th /mnt #扩展之后的容量显示 Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/myvg-mylv ext4 6.8G 14M 6.5G 1% /mnt [root@neolinux ~]# ll /mnt/ #/mnt目录下文件一样存在 total 44 -rw-r--r-- 1 root root 25419 Jun 4 02:55 functions drwx------ 2 root root 16384 Jun 4 02:51 lost+found 在线扩容步骤总结： 1、检查VG的容量是否满足扩容需求，不满足，请先扩容VG 2、执行扩容LV物理边界命令 3、确认LV物理边界是否扩容成功 4、执行扩容LV逻辑边界 5、检查挂载目录容量，确认扩容完成
8、缩减LV容量
[root@neolinux ~]# umount /mnt #取消挂载 [root@neolinux ~]# e2fsck -f /dev/myvg/mylv #强制对磁盘进行检查 e2fsck 1.41.12 (17-May-2010) 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/myvg/mylv: 12/458752 files (0.0% non-contiguous), 65030/1835008 blocks [root@neolinux ~]# resize2fs /dev/myvg/mylv 3G #缩减LV的逻辑边界到3G容量大小 resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/myvg/mylv to 786432 (4k) blocks. The filesystem on /dev/myvg/mylv is now 786432 blocks long. [root@neolinux ~]# lvreduce /dev/myvg/mylv -L 3G #缩减LV物理边界到3G容量大小 WARNING: Reducing active logical volume to 3.00 GiB THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce mylv? [y/n]: y #告警，确认 Size of logical volume myvg/mylv changed from 7.00 GiB (448 extents) to 3.00 GiB (192 extents). Logical volume mylv successfully resized [root@neolinux ~]# lvs #检查LV容量缩减是否完成 LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert LV01 VG -wi-ao---- 9.77g LV02 VG -wi-ao---- 8.04g mylv myvg -wi-a----- 3.00g [root@neolinux ~]# mount /dev/myvg/mylv /mnt/ #重新挂载该LV [root@neolinux ~]# ll /mnt/ #检查数据依然存在 total 44 -rw-r--r-- 1 root root 25419 Jun 4 02:55 functions drwx------ 2 root root 16384 Jun 4 02:51 lost+found
9、移除PV
[root@neolinux ~]# vgreduce myvg /dev/sdb #在当LV挂载时，选择移除PV，在选择移除PV的时候，要考虑到该移除PV的总容量要小于当前该VG的剩余可用容量 Removed "/dev/sdb" from volume group "myvg" [root@neolinux ~]# pvs #确认PV已经移除VG PV VG Fmt Attr PSize PFree /dev/sda3 VG lvm2 a-- 17.80g 0 /dev/sdb lvm2 --- 2.00g 2.00g /dev/sdc myvg lvm2 a-- 2.98g 2.98g /dev/sdd myvg lvm2 a-- 4.98g 1.98g [root@neolinux ~]# ll /mnt/ #LV挂载数据依然存在 total 44 -rw-r--r-- 1 root root 25419 Jun 4 02:55 functions drwx------ 2 root root 16384 Jun 4 02:51 lost+found [root@neolinux ~]# vgs VG #PV #LV #SN Attr VSize VFree VG 1 2 0 wz--n- 17.80g 0 myvg 2 1 0 wz--n- 7.97g 4.97g #我们在此进行LV缩减至2G [root@neolinux ~]# df -Th /mnt Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/myvg-mylv ext4 2.0G 3.1M 1.9G 1% /mnt [root@neolinux ~]# pvs #可以清楚的看到LV上的数据保存在/dev/sdc这个PV中， PV VG Fmt Attr PSize PFree /dev/sda3 VG lvm2 a-- 17.80g 0 /dev/sdb lvm2 --- 2.00g 2.00g /dev/sdc myvg lvm2 a-- 2.98g 1008.00m /dev/sdd myvg lvm2 a-- 4.98g 4.98g [root@neolinux ~]# #数据在/dev/sdc这个PV中，我们需要把这个PV移除VG [root@neolinux ~]# pvmove /dev/sdc /dev/sdd #移动/dev/sdc上的PE到/dev/sdd /dev/sdc: Moved: 0.0% /dev/sdc: Moved: 100.0% [root@neolinux ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda3 VG lvm2 a-- 17.80g 0 /dev/sdb lvm2 --- 2.00g 2.00g /dev/sdc myvg lvm2 a-- 2.98g 2.98g #可以看到/sdc上没有存在数据 /dev/sdd myvg lvm2 a-- 4.98g 2.98g #实际存储的数据转移到/dev/sdd上 [root@neolinux ~]# #接下来我们可以安心把/dev/sdc从VG上卸载 [root@neolinux ~]# vgreduce myvg /dev/sdc Removed "/dev/sdc" from volume group "myvg" [root@neolinux ~]# ll /mnt/ #此时LV不受任何影响 total 44 -rw-r--r-- 1 root root 25419 Jun 4 03:35 functions drwx------ 2 root root 16384 Jun 4 03:34 lost+found [root@neolinux ~]#
10、PV移除
[root@neolinux ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda3 VG lvm2 a-- 17.80g 0 /dev/sdb lvm2 --- 2.00g 2.00g /dev/sdc lvm2 --- 3.00g 3.00g /dev/sdd myvg lvm2 a-- 4.98g 2.98g [root@neolinux ~]# pvremove /dev/sdb Labels on physical volume "/dev/sdb" successfully wiped
11、快照snopshot功能
[root@neolinux ~]# df -Th /mnt #检查mylv，大小为2G，使用3.1M Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/myvg-mylv ext4 2.0G 3.1M 1.9G 1% /mnt [root@neolinux ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert LV01 VG -wi-ao---- 9.77g LV02 VG -wi-ao---- 8.04g mylv myvg -wi-ao---- 2.00g [root@neolinux ~]# vgs #查看mylv所在的vg还有6G的容量，足够我们创建快照卷 VG #PV #LV #SN Attr VSize VFree VG 1 2 0 wz--n- 17.80g 0 myvg 2 1 0 wz--n- 7.97g 5.97g [root@neolinux ~]# lvcreate -L 3G -s -n mylv-snapshot /dev/myvg/mylv #创建快照卷，大小为3G，快照卷选择的大小，应该是需要快照的卷容量加上需要备份时间内此卷的变化容量 Reducing COW size 3.00 GiB down to maximum usable size 2.02 GiB. #比如说快照备份时间需要30分钟，在30分钟原卷数据变化量1G，那么我们应该选择快照卷的大小为大于2G+1G Logical volume "mylv-snapshot" created.
12、对快照卷备份管理
[root@neolinux ~]# mount /dev/myvg/mylv-snapshot /opt/ #快照卷是需要格式化就可以挂载，查看 [root@neolinux ~]# ls /opt/ functions lost+found [root@neolinux ~]# touch /mnt/test #在原卷创建test文件 [root@neolinux ~]# ll /mnt/ total 44 -rw-r--r-- 1 root root 25419 Jun 4 03:35 functions drwx------ 2 root root 16384 Jun 4 03:34 lost+found -rw-r--r-- 1 root root 0 Jun 5 03:32 test [root@neolinux ~]# [root@neolinux ~]# tar JcPf /backup/mylv-`date +%F`.tar.xz /opt/* #对快照卷文件系统级别备份 [root@neolinux ~]# dd if=/dev/myvg/mylv-snapshot of=/backup/mylv-`date +%F`.dd #对快照卷做块级别的备份 4194304+0 records in 4194304+0 records out 2147483648 bytes (2.1 GB) copied, 45.3875 s, 47.3 MB/s [root@neolinux ~]# umount /opt/ #对快照卷取消挂载 [root@neolinux ~]# lvremove /dev/myvg/mylv-snapshot #删除快照卷 Do you really want to remove active logical volume mylv-snapshot? [y/n]: y Logical volume "mylv-snapshot" successfully removed [root@neolinux ~]#
13、模拟对原卷破坏
[root@neolinux ~]# dd if=/dev/zero of=/dev/myvg/mylv bs=512 count=1000 #模拟对原卷的破坏 1000+0 records in 1000+0 records out 512000 bytes (512 kB) copied, 0.0212266 s, 24.1 MB/s [root@neolinux ~]# ll /mnt/ #检查数据，其实这个时候原卷已经损坏 total 0 [root@neolinux ~]# mount /dev/mapper/VG-LV01 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/VG-LV02 on /usr type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) /dev/mapper/myvg-mylv on /mnt type ext4 (rw) [root@neolinux ~]# umount /mnt/ #取消挂载原卷 [root@neolinux ~]# mount /dev/myvg/mylv /mnt/ #重新挂载原卷，已经挂载不上去了 mount: you must specify the filesystem type
14、使用对数据块的备份恢复原卷数据
[root@neolinux ~]# dd if=/backup/mylv-2016-06-05.dd of=/dev/myvg/mylv #对快照卷进行恢复 4194304+0 records in 4194304+0 records out 2147483648 bytes (2.1 GB) copied, 53.3457 s, 40.3 MB/s [root@neolinux ~]# mount /dev/myvg/mylv /mnt #重新挂载 [root@neolinux ~]# ll /mnt/ #检查数据为快照卷备份那时刻的数据 total 44 -rw-r--r-- 1 root root 25419 Jun 4 03:35 functions drwx------ 2 root root 16384 Jun 4 03:34 lost+found [root@neolinux ~]#
15、编写一个小脚本对lvm进行定时备份
#!/bin/bash #/root/scripts/backuplvm.sh # /sbin/lvcreate -L 3G -s -n mylv-snapshot /dev/myvg/mylv /bin/mount /dev/myvg/mylv-snapshot /opt/ /bin/tar JcPf /backup/mylv-`date +%F` /opt/* /bin/umount /opt/ /sbin/lvremove /dev/myvg/mylv-snapshot # [root@neolinux scripts]# chmod +x /root/scripts/backuplvm.sh [root@neolinux scripts]# crontab -l #每天晚上23点59分59秒开始备份 0 0 * * * /bin/bash /root/scripts/backuplvm.sh [root@neolinux scripts]#
原创文章，作者：nice_neo_linux，如若转载，请注明出处：http://www.178linux.com/17666
