Linux - 通过LVM对磁盘进行动态扩容
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2022-08-17 16:56:25
Linux系统中如何挂载磁盘? 如何支持磁盘空间的动态扩容? LVM技术是做什么的? 本篇文章手把手教你用两种方式挂载磁盘, 欢迎交流^_^ ......
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
使用lvm时技术时, 情况有所不同:
(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;
强烈建议对拥有多个磁盘的系统, 使用lvm管理磁盘.
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 .
[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
参考资料
版权声明
作者: ma_shoufeng(马瘦风)
出处: 博客园
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