内容简介:LVM、物理卷、逻辑卷、卷组、快照
关于LVM简单的理解【百度百科很详细】,现在 php 开发的一个项目,涉及到拍高清照片,项目盘20G很快被占满了,目前我想到的解决方式可能有 (1).虚拟目录指定到其他盘符或分区,但是还要修改项目中图片存放路径,很麻烦 (2).找一个分区mount到图片目录 (3).用fdisk 先删除原有分区, 再重建分区, 起始cylinder 绝对不可以改,这样会破坏原分区的数据 (4).再就是今天要学习的LVM,它把最下面的物理盘【物理卷】/dev/sda1,/dev/sdb1…逻辑成一个大磁盘【卷组】,然后分配给逻辑分区【逻辑卷】
这样不管是扩容还是减容,都只是逻辑上的变化,而最下层的物理卷根本没有变化,所以不会影响数据的毁坏【文件系统层次看见的是逻辑分区】,当数据存入取出的时候,比如逻辑分区1到逻辑集合(大磁盘)之间的最小数据块或者说是基本单位【类比raid中的CHUNK】叫做LE逻辑快,而逻辑集合(大磁盘)到物理卷的基本单位是PE物理块,在同一个卷组中,LE的大小和PE是相同的,并且一一对应。下面的物理卷坏了任意一块上面的逻辑卷也不能使用,因为LE在下面的每个磁盘都有【可以使用前面说的raid技术】
要想扩大上面逻辑分区的最大容量【逻辑边界】,就必须扩大中间的卷组,最终还是要扩大底层的磁盘组【物理边界】,当要去掉底层的一块盘时,它会先把该盘数据转移到其他的盘,然后才拆卸
创建物理卷【pv】
停止阵列
停止raid占用的分区【上一章raid遗留问题】,否则可能出现资源繁忙或资源被占用
[root@localhost ~]# mdadm -S /dev/md126 mdadm: stopped /dev/md126 [root@localhost ~]# mdadm -S /dev/md127 mdadm: stopped /dev/md127
更改分区类型
用fdisk把分区类型改为8e
[root@localhost ~]# fdisk /dev/sdb 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): t Partition number (1-6): 1 Hex code (type L to list codes): 8e Changed system type of partition 1 to 8e (Linux LVM) Command (m for help): t Partition number (1-6): 2 Hex code (type L to list codes): 8e Changed system type of partition 2 to 8e (Linux LVM) Command (m for help): p Disk /dev/sdb: 10.7 GB, 10737418240 bytes 255 heads, 63 sectors/track, 1305 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: 0xd25c91c2 Device Boot Start End Blocks Id System /dev/sdb1 1 132 1060258+ 8e Linux LVM【改成LVM分区类型】 /dev/sdb2 133 264 1060290 8e Linux LVM /dev/sdb3 265 396 1060290 8e Linux LVM /dev/sdb4 397 1305 7301542+ 5 Extended /dev/sdb5 397 528 1060258+ 8e Linux LVM /dev/sdb6 529 660 1060258+ 8e Linux LVM Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
pvcreate创建pv
现在把sdb3和sdb5做成pv【物理卷】
[root@localhost ~]# pvcreate /dev/sdb{3,5} Physical volume "/dev/sdb3" successfully created Physical volume "/dev/sdb5" successfully created
pvscan查看pv
[root@localhost ~]# pvscan PV /dev/sdb3 lvm2 [1.01 GiB] PV /dev/sdb5 lvm2 [1.01 GiB] Total: 2 [2.02 GiB] / in use: 0 [0 ] / in no VG: 2 [2.02 GiB]
pvdisplay查看详细信息
[root@localhost ~]# pvdisplay "/dev/sdb3" is a new physical volume of "1.01 GiB" --- NEW Physical volume --- PV Name /dev/sdb3 VG Name PV Size 1.01 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0【当pv加入到卷组以后PE才的个数才知道有多少】 Allocated PE 0 PV UUID U1ndh1-u5pu-v0WF-PrWg-fwuO-1Blw-4Wbz0f "/dev/sdb5" is a new physical volume of "1.01 GiB" --- NEW Physical volume --- PV Name /dev/sdb5 VG Name PV Size 1.01 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID 79gSEo-q0xS-M7Q5-Wlmc-qbCz-tH2Z-ZPMf57
pvmove移动pv数据
现在要移除一个pv,首先要不数据转移到其他的pv上,然后使用vgreduce去掉该pv
[root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb3 myvg lvm2 a-- 1.01g 1.01g /dev/sdb5 myvg lvm2 a-- 1.01g 1.01g【还没有移除】 [root@localhost ~]# pvmove /dev/sdb5 No data to move for myvg【我的/dev/sdb5还没数据】 [root@localhost ~]# vgreduce myvg /dev/sdb5 Removed "/dev/sdb5" from volume group "myvg" [root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb3 myvg lvm2 a-- 1.01g 1.01g /dev/sdb5 lvm2 --- 1.01g 1.01g【已经移除】
pvremove删除pv数据
[root@localhost ~]# pvremove /dev/sdb5 Labels on physical volume "/dev/sdb5" successfully wiped
创建卷组【vg】
vgcreate创建vg
用法:vgcreate 卷组名 物理卷名
- -s #:指定PE大小,默认是4M
[root@localhost ~]# vgcreate myvg /dev/sdb{3,5} Volume group "myvg" successfully created
vgs查看vg
[root@localhost ~]# vgs VG #PV #LV #SN Attr VSize VFree myvg 2 0 0 wz--n- 2.02g 2.02g
vgdisplay 查看vg
查看vg详细信息查看PE大小,pvdisplay查看PE的个数
[root@localhost ~]# 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 2.02 GiB PE Size 4.00 MiB【PE大小】 Total PE 516 Alloc PE / Size 0 / 0 Free PE / Size 516 / 2.02 GiB VG UUID 87U1HI-Nr3b-ytsO-iw3K-lFG6-yVy9-uoZlXM [root@localhost ~]# pvdisplay --- Physical volume --- PV Name /dev/sdb3 VG Name myvg PV Size 1.01 GiB / not usable 3.44 MiB Allocatable yes PE Size 4.00 MiB【PE大小】 Total PE 258 Free PE 258【PE个数】 Allocated PE 0 PV UUID U1ndh1-u5pu-v0WF-PrWg-fwuO-1Blw-4Wbz0f --- Physical volume --- PV Name /dev/sdb5 VG Name myvg PV Size 1.01 GiB / not usable 3.41 MiB Allocatable yes PE Size 4.00 MiB Total PE 258 Free PE 258 Allocated PE 0 PV UUID 79gSEo-q0xS-M7Q5-Wlmc-qbCz-tH2Z-ZPMf57
vgremove删除vg
在还没有创建lg的时候可以删除vg,创建了lg有了数据就不能再删除了
[root@localhost ~]# vgremove myvg Volume group "myvg" successfully removed
vgreduce移除pv
[root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb3 myvg lvm2 a-- 1.01g 1.01g /dev/sdb5 myvg lvm2 a-- 1.01g 1.01g【还没有移除】 [root@localhost ~]# pvmove /dev/sdb5 No data to move for myvg【我的/dev/sdb5还没数据】 [root@localhost ~]# vgreduce myvg /dev/sdb5 Removed "/dev/sdb5" from volume group "myvg" [root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb3 myvg lvm2 a-- 1.01g 1.01g /dev/sdb5 lvm2 --- 1.01g 1.01g【已经移除】
vgextend扩展vg
扩展vg就要增加pv
[root@localhost ~]# vgextend myvg /dev/sdb5 Physical volume "/dev/sdb5" successfully created Volume group "myvg" successfully extended [root@localhost ~]# pvcreate /dev/sdb6 Can't open /dev/sdb6 exclusively. Mounted filesystem? [root@localhost ~]# cat /proc/mdstat【怎么自动被raid占用了???】 Personalities : [raid1] [raid0] md1 : inactive sdb6[2](S) 1059234 blocks super 1.2 md0 : active raid0 sdb2[1] sdb1[0] 2117632 blocks super 1.2 512k chunks unused devices: <none> [root@localhost ~]# mdadm -S /dev/md0【停止阵列】 mdadm: stopped /dev/md0 [root@localhost ~]# mdadm -S /dev/md1 mdadm: stopped /dev/md1 [root@localhost ~]# pvcreate /dev/sdb6【创建pv】 WARNING: software RAID md superblock detected on /dev/sdb6. Wipe it? [y/n]: y Wiping software RAID md superblock on /dev/sdb6. Physical volume "/dev/sdb6" successfully created [root@localhost ~]# vgextend myvg /dev/sdb6【添加到myvg卷组】 Volume group "myvg" successfully extended [root@localhost ~]# vgs VG #PV #LV #SN Attr VSize VFree myvg 3 0 0 wz--n- 3.02g 3.02g [root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb3 myvg lvm2 a-- 1.01g 1.01g /dev/sdb5 myvg lvm2 a-- 1.01g 1.01g /dev/sdb6 myvg lvm2 a-- 1.01g 1.01g
创建逻辑卷【LV】
lvcreate
用法:lvcreate -n LV_NAME -L #G VG_NAME
[root@localhost ~]# lvcreate -L 100M -n mylv myvg Rounding up size to full physical extent 104.00 MiB Logical volume "mylv" created
lvdisplay
[root@localhost ~]# lvdisplay --- Logical volume --- LV Path /dev/myvg/mylv【可以lvdisplay /dev/myvg/mylv】 LV Name mylv VG Name myvg LV UUID 8AbwtV-ZJ3c-MbnS-AjUz-3n1A-xRUX-5S2TBr LV Write Access read/write LV Creation host, time localhost.localdomain, 2017-04-30 15:55:25 +0800 LV Status available # open 0 LV Size 104.00 MiB Current LE 13 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0
创建文件系统并挂载
创建文件系统
[root@localhost ~]# mke2fs -j /dev/myvg/mylv mke2fs 1.41.12 (17-May-2010) 文件系统标签= 操作系统:Linux 块大小=1024 (log=0) 分块大小=1024 (log=0) Stride=0 blocks, Stripe width=0 blocks 26624 inodes, 106496 blocks 5324 blocks (5.00%) reserved for the super user 第一个数据块=1 Maximum filesystem blocks=67371008 13 block groups 8192 blocks per group, 8192 fragments per group 2048 inodes per group Superblock backups stored on blocks: 8193, 24577, 40961, 57345, 73729 正在写入inode表: 完成 Creating journal (4096 blocks): 完成 Writing superblocks and filesystem accounting information: 完成 This filesystem will be automatically checked every 30 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
挂载
[root@localhost ~]# mount /dev/myvg/mylv /mnt/test [root@localhost ~]# ls -l /mnt/test 总用量 12 drwx------. 2 root root 12288 4月 30 16:00 lost+found [root@localhost ~]# mount【查看挂载的设备记录】 /dev/sda2 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,rootcontext="system_u:object_r:tmpfs_t:s0") /dev/sda1 on /boot type ext4 (rw) /dev/sda5 on /home type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) /dev/mapper/myvg-mylv on /mnt/test type ext3 (rw)【在这发现一个myvg-mylv挂载了,并没有我们的设备mylv的挂载记录】
查看/dev/mapper/myvg-mylv和/dev/myvg/mylv,发现都指向了同一个设备/dev/dm-0,这说明真正的物理空间,也就是物理卷分配给了dm-0,mylv和myvg-mylv都是逻辑卷,仅仅是个软链接【自己的猜想,望大神指正】
[root@localhost ~]# ls -lh /dev/myvg/mylv lrwxrwxrwx. 1 root root 7 4月 30 16:00 /dev/myvg/mylv -> ../dm-0 [root@localhost ~]# ls -lh /dev/mapper/myvg-mylv lrwxrwxrwx. 1 root root 7 4月 30 16:00 /dev/mapper/myvg-mylv -> ../dm-0 [root@localhost ~]# ls -lh /dev/dm-0 brw-rw----. 1 root disk 253, 0 4月 30 16:00 /dev/dm-0
lvremove
证明一下上面的结论,我们卸载mylv和myvg-mylv;结果说明逻辑卷有两个名字,都是软链接
[root@localhost test]# lvremove /dev/mapper/myvg-mylv Logical volume myvg/mylv contains a filesystem in use. [root@localhost test]# lvremove /dev/myvg/mylv Logical volume myvg/mylv contains a filesystem in use. [root@localhost mnt]# umount /dev/myvg/mylv【软链接】 [root@localhost mnt]# lvremove /dev/mapper/myvg-mylv【软链接】 Do you really want to remove active logical volume mylv? [y/n]: y Logical volume "mylv" successfully removed [root@localhost mnt]# ls -l /dev/md-0【真正的逻辑设备md-0被移除】 ls: 无法访问/dev/md-0: 没有那个文件或目录 [root@localhost mnt]# lvs【真正的逻辑设备md-0被移除】 [root@localhost mnt]#
lvextend扩展逻辑卷
用法:-L [+]# /PATH/LV,”[+]”代表有”+”号时,代表加多少G【容量】,没有+号代表扩展到多少G
[root@localhost mnt]# lvcreate -L 1G -n mylv myvg【创建一个逻辑卷】 Logical volume "mylv" created [root@localhost mnt]# mke2fs -j /dev/myvg/mylv【创建文件系统】 mke2fs 1.41.12 (17-May-2010) 文件系统标签= 操作系统:Linux 块大小=4096 (log=2) 分块大小=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks 65536 inodes, 262144 blocks 13107 blocks (5.00%) reserved for the super user 第一个数据块=0 Maximum filesystem blocks=268435456 8 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376 正在写入inode表: 完成 Creating journal (8192 blocks): 完成 Writing superblocks and filesystem accounting information: 完成 This filesystem will be automatically checked every 26 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [root@localhost mnt]# mount /mnt/test mount: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so [root@localhost mnt]# mount /dev/myvg/mylv /mnt/test【挂载】 [root@localhost mnt]# vgs【查看vg】 VG #PV #LV #SN Attr VSize VFree myvg 3 1 0 wz--n- 3.02g 2.02g [root@localhost mnt]# lvextend -L 2G /dev/myvg/mylv【扩容】 Size of logical volume myvg/mylv changed from 1.00 GiB (128 extents) to 2.00 GiB (256 extents). Logical volume mylv successfully resized [root@localhost mnt]# df -lh Filesystem Size Used Avail Use% Mounted on /dev/sda2 3.9G 3.2G 463M 88% / tmpfs 504M 72K 504M 1% /dev/shm /dev/sda1 190M 26M 155M 15% /boot /dev/sda5 3.7G 34M 3.5G 1% /home /dev/mapper/myvg-mylv 1008M 34M 924M 4% /mnt/test【扩容后发现大小没变】
resize2fs重新加载逻辑卷
resize2fs命令被用来增大或者收缩未加载的“ext2/ext3”文件系统的大小。如果文件系统是处于mount状态下,那么它只能做到扩容,前提条件是内核支持在线resize。,linux kernel 2.6支持在mount状态下扩容但仅限于ext3文件系统。来自: http://man.linuxde.net/resize2fs
- -d:打开调试特性;
- -p:打印已完成的百分比进度条;
- -f:强制执行调整大小操作,覆盖掉安全检查操作;
- -F:开始执行调整大小前,刷新文件系统设备的缓冲区。
[root@localhost mnt]# resize2fs /dev/myvg/mylv 【重新加载逻辑卷】 resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/myvg/mylv is mounted on /mnt/test; on-line resizing required old desc_blocks = 1, new_desc_blocks = 1 Performing an on-line resize of /dev/myvg/mylv to 524288 (4k) blocks. The filesystem on /dev/myvg/mylv is now 524288 blocks long. [root@localhost mnt]# df -lh Filesystem Size Used Avail Use% Mounted on /dev/sda2 3.9G 3.2G 463M 88% / tmpfs 504M 72K 504M 1% /dev/shm /dev/sda1 190M 26M 155M 15% /boot /dev/sda5 3.7G 34M 3.5G 1% /home /dev/mapper/myvg-mylv 2.0G 34M 1.9G 2% /mnt/test【扩容成功】 [root@localhost mnt]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert mylv myvg -wi-ao---- 2.00g
lvreduce缩减逻辑卷
注意:
- 不能在线缩减,先卸载
- 确保缩减后的空间大小依然能存储原有的数据
- 在缩减之前应该先强行检查文件系统,以确保文件系统处于一致性状态【e2fsck -f】
缩减逻辑卷刚好和上面相反,先resize2fs再lvreduce
[root@localhost mnt]# df -lh【确保缩减后的空间大小依然能存储原有的数据,df只能查看挂载的分区】 Filesystem Size Used Avail Use% Mounted on /dev/sda2 3.9G 3.2G 463M 88% / tmpfs 504M 72K 504M 1% /dev/shm /dev/sda1 190M 26M 155M 15% /boot /dev/sda5 3.7G 34M 3.5G 1% /home /dev/mapper/myvg-mylv 2.0G 34M 1.9G 2% /mnt/test [root@localhost mnt]# umount /mnt/test【不能在线缩减,先卸载】 [root@localhost mnt]# mount【确保已经卸载】 /dev/sda2 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,rootcontext="system_u:object_r:tmpfs_t:s0") /dev/sda1 on /boot type ext4 (rw) /dev/sda5 on /home type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) [root@localhost mnt]# e2fsck -f /dev/myvg/mylv【确保文件系统处于一致性状态】 e2fsck 1.41.12 (17-May-2010) 第一步: 检查inode,块,和大小 第二步: 检查目录结构 第3步: 检查目录连接性 Pass 4: Checking reference counts 第5步: 检查簇概要信息 /dev/myvg/mylv: 11/131072 files (0.0% non-contiguous), 16821/524288 blocks [root@localhost mnt]# resize2fs /dev/myvg/mylv 1G【调整文件系统大小为1G】 resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/myvg/mylv to 262144 (4k) blocks. The filesystem on /dev/myvg/mylv is now 262144 blocks long. [root@localhost mnt]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert mylv myvg -wi-a----- 2.00g【逻辑卷还没调整】 [root@localhost mnt]# lvreduce -L 1G /dev/myvg/mylv【缩减逻辑卷】 WARNING: Reducing active logical volume to 1.00 GiB THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce mylv? [y/n]: y Size of logical volume myvg/mylv changed from 2.00 GiB (256 extents) to 1.00 GiB (128 extents). Logical volume mylv successfully resized [root@localhost mnt]# mount /dev/myvg/mylv /mnt/test【挂载】 [root@localhost mnt]# mount /dev/sda2 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,rootcontext="system_u:object_r:tmpfs_t:s0") /dev/sda1 on /boot type ext4 (rw) /dev/sda5 on /home type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) /dev/mapper/myvg-mylv on /mnt/test type ext3 (rw) [root@localhost mnt]# df -lh【查看已挂载磁盘分区的使用信息】 Filesystem Size Used Avail Use% Mounted on /dev/sda2 3.9G 3.2G 463M 88% / tmpfs 504M 72K 504M 1% /dev/shm /dev/sda1 190M 26M 155M 15% /boot /dev/sda5 3.7G 34M 3.5G 1% /home /dev/mapper/myvg-mylv 1008M 34M 924M 4% /mnt/test
快照卷
快照一般都很小,它存的是原系统上要发生变化的文件,比如我要修改一个文件,快照会首先把文件存起来,然后修改过后的文件在原系统,未修改的文件存进了快照。这样就实现了数据备份,这样快照卷刚开始很小,时间长了就大了。它这个备份存的是软件资料的备份。而我们的raid1和raid10存的备份是磁盘的备份。我的磁盘直接坏掉了,快照肯定没有备份下来,还原也是没用的【快照也是存在磁盘上的】。
快照卷的好多文件其实都是和原文件系统共用的,所以快照卷相当于一个分区的另一个入口,这样快照卷肯定在该分区上,对LVM而言就是在一个卷组上【因为PE在vg下面的每个PV上都有】
要求:
- 生命周期为整个快照的文件系统的生命周期,并且在该周期内原文件系统变化的文件大小不能超过快照卷,因为每有文件变化就会备份一份该文件变化之前的快照,最大不会超过快照的原文件系统大小
- 快照应该是只读
- 跟原卷在同一卷组
使用方法:lvcreate -L # -n SLV_NAME -s -p r /PATH/LV 【指定为那个逻辑卷创建的】
- -s:表示快照卷
- -p:指定权限r|w
- -L:快照卷大小
#test是逻辑卷mylv挂载目录 #test1是快照卷挂载目录 [root@localhost test]# ls lost+found [root@localhost test]# touch b.txt【创建快照前先在原文件系统创建一个b.txt】 [root@localhost test]# lvcreate -L 100M -n mylv-snap -s -p r /dev/myvg/mylv 【为mylv创建快照】 Rounding up size to full physical extent 104.00 MiB Logical volume "mylv-snap" created [root@localhost test]# mount /dev/myvg/mylv-snap /mnt/test1【挂载】 mount: block device /dev/mapper/myvg-mylv--snap is write-protected, mounting read-only [root@localhost test]# ls /mnt/test1【创建当前快照,这个b.txt其实也是/mnt/test的b.txt,快照只是入口】 b.txt lost+found [root@localhost test]# vi b.txt【编辑test下的b.txt,快照这个时候才备份,备份原来的空文件b.txt】 [root@localhost test]# cat b.txt dsadsaaaaa [root@localhost test]# cat /mnt/test1/b.txt【发现还是空,已经快照备份了】 [root@localhost test]# #删除快照 [root@localhost test]# umount /mnt/test1 [root@localhost test]# lvremove /dev/myvg/mylv-snap Do you really want to remove active logical volume mylv-snap? [y/n]: y Logical volume "mylv-snap" successfully removed
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