1 LVM是什么
1.1 概念解释
LVM(Logical Volume Manager), 逻辑卷管理, 是一种将一至多个硬盘的分区在逻辑上进行组合, 当成一个大硬盘来使用。
当硬盘空间不足时, 可以动态地添加其它硬盘的分区到已有的卷组中 —— 磁盘空间的动态管理。
1.2 为什么用LVM
LVM通常用于装备大量磁盘的系统, 比如服务器中的磁盘阵列.
但LVM同样适用于仅有一、两块硬盘的小系统.
1.2.1 不使用LVM时的扩容思路
传统的文件系统是基于分区的, 一个文件系统对应一个分区, 这种方式比较直观, 但不易改变:
(1) 不同的分区相互独立, 单独的文件不能跨分区存储, 容易出现硬盘的利用率不均衡;
(2) 当一个文件系统/分区装满时, 是不能对其进行扩容的, 只能采用重新分区/建立文件系统, 重新分区会丢失数据, 就要:
① 做数据的迁移和备份;
② 或者把分区中的数据移到另一个更大的分区中;
③ 或者采用符号连接的方式使用其它分区的空间 —— 都非常麻烦;(3) 如果要把硬盘上的多个分区合并在一起使用, 只能采用重新分区的方式, —— 需要做好数据的备份与恢复.
1.2.2 使用LVM时的扩容思路
(1) 硬盘的多个分区由LVM统一管理为卷组, 可以很轻松地加入或移走某个分区 —— 也就是扩大或减小卷组的可用容量, 充分利用硬盘空间;
(2) 文件系统建立在逻辑卷上, 而逻辑卷可以根据需要改变大小(在卷组容量范围内)以满足要求;
(3) 文件系统建立在LVM上, 可以跨分区存储访问, 更加方便;
1.3 名词解释
PV(Physical Volume): 物理卷, 处于LVM最底层, 可以是物理硬盘或者分区;
PP(Physical Extend): 物理区域, PV中可以用于分配的最小存储单元, 可以在创建PV的时候指定, 如1M, 2M, 4M, 8M…..组成同一VG中所有PV的PE大小应该相同;
VG(Volume Group): 卷组, 建立在PV之上, 可以含有一个到多个PV;
LV(Logical Volume): 逻辑卷, 建立在VG之上, 相当于原来分区的概念, 不过大小可以动态改变.
2 普通的挂载磁盘方法
2.1 创建分区的主要操作
(1) 查看分区情况 – fdisk -l
[root@localhost ~]# fdisk -l Disk /dev/sda: 299.0 GB, 298999349248 bytes # 磁盘/dev/sda 255 heads, 63 sectors/track, 36351 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: 0x4d69fe0e Device Boot Start End Blocks Id System /dev/sda1 * 1 26 204800 83 Linux # 分为2个区, sda1 Partition 1 does not end on cylinder boundary. /dev/sda2 26 36352 291785728 8e Linux LVM # sda2 # 磁盘/dev/sdb没有分区 Disk /dev/sdb: 4000.0 GB, 3999999721472 bytes 255 heads, 63 sectors/track, 486305 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) 查看已有磁盘 – lsblk
[root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 278.5G 0 disk ├─sda1 8:1 0 200M 0 part /boot └─sda2 8:2 0 278.3G 0 part └─VolGroup-LogVol (dm-0) 253:0 0 1.9T 0 lvm / # LVM类型的分区 sdb 8:32 0 3.7T 0 disk # 还没有分区的新磁盘
(3) 对新磁盘进行分区 – fdisk /dev/sdb
[root@localhost ~]# 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 0xf91f8c4c. 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: The size of this disk is 4.0 TB (4000225165312 bytes). DOS partition table format can not be used on drives for volumes larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID partition table format (GPT). 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 # n 表示新建分区 Command action e extended p primary partition (1-4) p # p 表示分区类型为主分区, 主分区只有1-4种选择 Partition number (1-4): 1 # 主分区的编号 First cylinder (1-486333, default 1): # 开始扇区号, 直接回车, 使用默认值1 Using default value 1 # 结束扇区号, 使用默认值 --- 这里只加载了新磁盘的一半(2T), 所以还需要再次创建分区/dev/sdb2使用剩下的一半. Last cylinder, +cylinders or +size{K,M,G} (1-267349, default 267349): Using default value 267349 Command (m for help): w # 将上述设置写入分区表并退出 The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
(4) 再次查看分区情况 – fdisk -l
多出来一个/dev/sdb1的区, 这个1就是之前主分区之后指定的分区编号.
[root@localhost ~]# fdisk -l Disk /dev/sda: 299.0 GB, 298999349248 bytes 255 heads, 63 sectors/track, 36351 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: 0x4d69fe0e 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 36352 291785728 8e Linux LVM # /dev/sdb磁盘: Disk /dev/sdb: 4000.0 GB, 3999999721472 bytes 255 heads, 63 sectors/track, 486305 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: 0x8f3043b5 # 多出来的分区/dev/sdb1 Device Boot Start End Blocks Id System /dev/sdb1 1 267349 2147480811 83 Linux ......
(5) 查看当前分区表中的分区信息 – cat /proc/partitions
[root@localhost ~]# cat /proc/partitions major minor #blocks name 8 0 291991552 sda 8 1 204800 sda1 8 2 291785728 sda2 8 32 3906249728 sdb # 添加的新磁盘 8 33 2147480811 sdb1 # 创建的新分区 253 0 2046660608 dm-0
如果创建完之后，cat /proc/partitions 查看不到对应的分区, 使用 parprobe 刷新命令即可:
[root@localhost ~]# partprobe /dev/sdc
2.2 格式化新分区
(1) 格式化新分区 – mkfs -t
这里建议将新分区格式化为ext4文件类型, 还有ext2, ext3等文件类型, 区别请参考博客 ext2、ext3与ext4的区别 .
[root@localhost ~]# mkfs -t ext4 /dev/sdb1 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 134217728 inodes, 536870202 blocks 26843510 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=4294967296 16384 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, 1605632, 2654208, 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 102400000, 214990848, 512000000 Writing inode tables: 8874/16384
(2) 等待一小会后, 将出现下述提示, 说明格式化完成:
Writing inode tables: done Creating journal (32768 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.
2.3 挂载新分区
(1) 创建目录, 并将 /dev/sdb1挂在到该目录下:
[root@localhost /]# mkdir data && cd /data [root@localhost data]# mount /dev/sdc1 /data1
(2) 查看挂载是否成功:
[root@localhost data]# df -l Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/VolGroup-LogVol 286901696 18601728 253726196 7% / tmpfs 66020980 0 66020980 0% /dev/shm /dev/sda1 495844 33476 436768 8% /boot # 挂载成功: /dev/sdb1 2113784984 202776 2006208168 1% /data
2.4 设置开机自动挂载
编辑文件 /etc/fstab:
[root@localhost data]# vim /etc/fstab # 文件内容如下: # /etc/fstab # Created by anaconda on Wed Sep 12 10:41:40 2018 # # 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 # /dev/mapper/VolGroup-LogVol / ext4 defaults 1 1 /dev/sdb1 /data ext4 defaults 1 1 UUID=22b1d425-d050-43c3-a735-06d48bbb9051 /boot ext4 defaults 1 2 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
3 LVM方式挂载磁盘 – 推荐
3.1 查看磁盘容量信息
[root@localhost ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VG-LogVol 1.9T 1.8T 61G 97% / # LVM卷组-逻辑卷 tmpfs 63G 0 63G 0% /dev/shm /dev/sda1 485M 40M 421M 9% /boot
3.2 查看磁盘扇区信息
[root@localhost ~]# fdisk -l Disk /dev/sda: 299.0 GB, 298999349248 bytes # 磁盘/dev/sda 255 heads, 63 sectors/track, 36351 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: 0x4d69fe0e Device Boot Start End Blocks Id System /dev/sda1 * 1 26 204800 83 Linux # 分为2个区, sda1 Partition 1 does not end on cylinder boundary. /dev/sda2 26 36352 291785728 8e Linux LVM # LVM类型的sda2 # 新添加的磁盘/dev/sdb, 没有分区 Disk /dev/sdb: 4000.0 GB, 3999999721472 bytes 255 heads, 63 sectors/track, 486305 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 # LVM格式的卷组信息: Disk /dev/mapper/VolGroup-LogVol: 4294 MB, 4294967296 bytes 255 heads, 63 sectors/track, 522 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
3.3 创建分区
[root@localhost ~]# 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 0x5b3d66ba. 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: The size of this disk is 4.0 TB (3999999721472 bytes). DOS partition table format can not be used on drives for volumes larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID partition table format (GPT). 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 # 添加分区 Command action e extended p primary partition (1-4) p # 添加主分区 Partition number (1-4): 1 # 1号主分区, 即/dev/sdb1 First cylinder (1-486305, default 1): Using default value 1 Last cylinder, +cylinders or +size{K,M,G} (1-267349, default 267349): 486305 Value out of range. Last cylinder, +cylinders or +size{K,M,G} (1-267349, default 267349): Using default value 267349 Command (m for help): n # 继续添加分区 Command action e extended p primary partition (1-4) p Partition number (1-4): 2 # 2号主分区, 即/dev/sdc2 First cylinder (267350-486305, default 267350): Using default value 267350 Last cylinder, +cylinders or +size{K,M,G} (267350-486305, default 486305): Using default value 486305 Command (m for help): p # 打印分区信息: Disk /dev/sdb: 4000.0 GB, 3999999721472 bytes 255 heads, 63 sectors/track, 486305 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: 0x5b3d66ba Device Boot Start End Blocks Id System /dev/sdb1 1 267349 2147480811 83 Linux /dev/sdb2 267350 486305 1758764070 83 Linux Command (m for help): t # 转换类型 Partition number (1-4): 1 Partition number (1-4): 1 # 修改/dev/sdb1为Linux LVM类型: Hex code (type L to list codes): L # 查看可用类型: 0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris 1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT- 2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT- 3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT- 4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx 5 Extended 42 SFS 86 NTFS volume set da Non-FS data 6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / . 7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility 8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt 9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/ 10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b 11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor 12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor 14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary 16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS 17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE 18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto 1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep 1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT 1e Hidden W95 FAT1 Hex code (type L to list codes): 8e # 修改为8e, 即Linux LVM类型 Changed system type of partition 1 to 8e (Linux LVM) Command (m for help): t Partition number (1-4): 2 # 修改/dev/sdc2为Linux LVM类型 Hex code (type L to list codes): 8e Changed system type of partition 2 to 8e (Linux LVM) Command (m for help): p # 再次查看相关信息: Disk /dev/sdc: 4000.0 GB, 3999999721472 bytes 255 heads, 63 sectors/track, 486305 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: 0x5b3d66ba Device Boot Start End Blocks Id System /dev/sdb1 1 267349 2147480811 8e Linux LVM # Id已改变 /dev/sdb2 267350 486305 1758764070 8e Linux LVM Command (m for help): w # 保存并退出 The partition table has been altered! # 修改成功 Calling ioctl() to re-read partition table. Syncing disks.
3.4 创建物理卷
[root@localhost ~]# pvcreate /dev/sdb1 Physical volume "/dev/sdb1" successfully created [root@localhost ~]# pvcreate /dev/sdb2 Physical volume "/dev/sdb2" successfully created
3.5 扩展卷组
# 查看已有卷组, 发现该卷组就是需要扩容的卷组, 就不必再次创建卷组, 而是直接扩展卷组即可: [root@localhost ~]# vgs VG #PV #LV #SN Attr VSize VFree VolGroup 2 2 0 wz--n- 1.91t 0 # 扩展卷组: [root@localhost ~]# vgextend VolGroup /dev/sdb1 Volume group "VolGroup" successfully extended [root@localhost ~]# vgextend VolGroup /dev/sdb2 Volume group "VolGroup" successfully extended
说明: 如果出现下述无法挂载物理磁盘到卷组中的信息, 说明这块物理磁盘已经挂载了, 需要先卸载, 然后再执行创建分区+卷组的操作:
[root@localhost /]# vgextend VolGroup /dev/sdb1 No physical volume label read from /dev/sdb1 Physical volume /dev/sdb1 not found Can't open /dev/sdb1 exclusively. Mounted filesystem? Unable to add physical volume '/dev/sdb1' to volume group 'VolGroup'.
3.6 扩展逻辑卷
# 扩展逻辑卷, 即扩容: [root@localhost ~]# lvextend -l +100%FREE /dev/mapper/VolGroup-LogVol Extending logical volume lv_root to 5.54 TiB Logical volume lv_root successfully resized # 上述命令是将所有的空闲空间都扩容到逻辑卷中, 也可指定扩容的大小: lvextend -l +100G /dev/mapper/VolGroup-LogVol
3.7 查看磁盘卷组信息
[root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 278.5G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 278G 0 part ├─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm / sdb 8:16 0 1.6T 0 disk └─sdb1 8:17 0 1.6T 0 part └─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm / sdc 8:32 0 3.7T 0 disk ├─sdc1 8:33 0 2T 0 part │ └─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm / └─sdc2 8:34 0 1.7T 0 part └─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm /
3.8 调整文件系统的大小
# CentOS 7重新读取磁盘大小: [root@localhost ~]# xfs_growfs /dev/mapper/VolGroup-LogVol xfs_growfs: /dev/mapper/VolGroup-LogVol is not a mounted XFS filesystem # CentOS 6.5重新读取磁盘大小: # ext4格式, resize2fs会遍历整个磁盘, 速度比较慢, 但是不影响读写数据, 可以令其在后台运行. [root@localhost ~]# resize2fs /dev/mapper/VolGroup-LogVol resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/mapper/VolGroup-LogVol is mounted on /; on-line resizing required old desc_blocks = 122, new_desc_blocks = 355 Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 1487098880 (4k) blocks. # 等了差不多20分钟, 出来了下面这货: The filesystem on /dev/mapper/VolGroup-LogVol is now 1487098880 blocks long. # 赶紧看下扩容成果吧: [root@localhost ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup-LogVol 5.5T 1.8T 3.5T 34% / # 扩容成功 tmpfs 63G 0 63G 0% /dev/shm /dev/sda1 485M 40M 421M 9% /boot
3.9 附录 – 创建卷组
对应 [3.5] 节的扩展卷组, 如果卷组不存在, 则需要创建之. 下述VolGroup是卷组名称.
vgcreate VolGroup /dev/sdb1 # 创建逻辑卷, 名称为: mylv. (操作系统中将产生: /dev/VolGroup/mylv目录) # 将当前卷组中的100G空间分配到逻辑卷中 lvcreate -L 100G VolGroup -n mylv # 或将当前卷组中的所有空闲空间全都分配到逻辑卷中: lvcreate -l +100%FREE VolGroup -n mylv # 格式化逻辑卷组: mkfs -t ext4 /dev/VolGroup/mylv # 挂载卷组到指定目录下, 如果是挂载到根目录, 则无需向/etc/fstab文件中添加启动项. mount -t ext4 /dev/VolGroup/mylv /data
