Linux巩固篇007-Linux 磁盘阵列技术

简介: 纸上得来终觉浅,绝知此事要躬行

前言

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常用命令汇总

RAID

通过把多个硬盘设备组合成一个容量更大、安全性更好的磁盘阵列,并把数据切割成多个区段后分别存放在各个不同的物理硬盘设备上,然后利用分散读写技术来提升磁盘阵列整体的性能,同时把多个重要数据的副本同步到不同的物理硬盘设备上,从而起到了非常好的数据冗余备份效果,简单来讲就是不把鸡蛋放到同一个篮子

RAID 0

RAID 0 技术把多块物理硬盘设备(至少两块)通过硬件或软件的方式串联在一起,组成一个大的卷组,disk1 和disk2 硬盘设

备会分别保存数据资料,最终实现分开写入、读取的效果

image.png

RAID 1

写入数据时,是将数据同时写入到多块硬盘设备上(可以将其视为数据的镜像或备份)。当其中某一块硬盘发生故障后,一般会立即自动以热交换的方式来恢复数据的正常使用

image.png

RAID 5

parity 部分存放的就是数据的奇偶校验信息,当硬盘设备出现问题后通过奇偶校验信息来尝试重建损坏的数据

image.png

RAID 10

RAID 10 技术是RAID 1+RAID 0 技术的一个“组合体”在不考虑成本的情况下RAID 10 的性能都超过了RAID 5

image.png

部署磁盘阵列

虚拟机中添加4 块硬盘设备来制作一个RAID 10 磁盘阵列,添加硬盘方式请看006章节,添加完毕后学习一个新的命令

image.png

mdadm 命令

mdadm 命令用于管理Linux 系统中的软件RAID 硬盘阵列,格式为“mdadm [模式]  [选项] [成员设备名称]”

image.png

使用 mdadm 命令创建RAID 10,名称为“/dev/md0”

-C 参数代表创建一个RAID 阵列卡

-v参数显示创建的过程,追加一个设备名称/dev/md0

-a yes 参数代表自动创建设备文件

-n 4 参数代表使用4 块硬盘部署

-l 10 参数则代表RAID 10 方案

[root@linux ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000cac32
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      616447      307200   83  Linux
/dev/sda2          616448     4810751     2097152   82  Linux swap / Solaris
/dev/sda3         4810752    41943039    18566144   83  Linux
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sdd: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sde: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
[root@linux ~]# mdadm -Cv /dev/md0 -a yes -n 4 -l 10 /dev/sdb /dev/sdc /dev/sdd /dev/sde
mdadm: layout defaults to n2
mdadm: layout defaults to n2
mdadm: chunk size defaults to 512K
mdadm: size set to 20954112K
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

把制作好的 RAID 磁盘阵列格式化为ext4 格式,同006章节内容

[root@linux ~]# mkfs.ext4 /dev/md0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=128 blocks, Stripe width=256 blocks
2621440 inodes, 10477056 blocks
523852 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2157969408
320 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
Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

创建挂载点然后把硬盘设备进行挂载操作

[root@linux ~]# mkdir /DAID
[root@linux ~]# mount /dev/md0 /DAID
[root@linux ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        18G  5.6G   13G  32% /
devtmpfs        472M     0  472M   0% /dev
tmpfs           488M     0  488M   0% /dev/shm
tmpfs           488M  8.6M  479M   2% /run
tmpfs           488M     0  488M   0% /sys/fs/cgroup
/dev/sda1       297M  138M  160M  47% /boot
tmpfs            98M  4.0K   98M   1% /run/user/42
tmpfs            98M   32K   98M   1% /run/user/1001
/dev/sr0        4.2G  4.2G     0 100% /run/media/weihongbin/CentOS 7 x86_64
/dev/md0         40G   49M   38G   1% /DAID

查看/dev/md0 磁盘阵列的详细信息,并把挂载信息写入到配置文件中,使其永久生效

[root@linux ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Thu Oct 20 14:40:14 2022
        Raid Level : raid10
        Array Size : 41908224 (39.97 GiB 42.91 GB)
     Used Dev Size : 20954112 (19.98 GiB 21.46 GB)
      Raid Devices : 4
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Thu Oct 20 14:43:43 2022
             State : clean 
    Active Devices : 4
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 0
            Layout : near=2
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : d9eb6af0:515bcea2:ee3cb41b:895a3b3f
            Events : 28
    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync set-A   /dev/sdb
       1       8       32        1      active sync set-B   /dev/sdc
       2       8       48        2      active sync set-A   /dev/sdd
       3       8       64        3      active sync set-B   /dev/sde
[root@linux ~]# echo "/dev/md0 /RAID ext4 defaults 0 0" >> /etc/fstab

损坏磁盘阵列及修复

确认有一块物理硬盘设备出现损坏而不能继续正常使用后,使用mdadm 命令将其移除,查看RAID 磁盘阵列的状态,发现状态已经改变

[root@linux ~]# mdadm /dev/md0 -f /dev/sdb
mdadm: set /dev/sdb faulty in /dev/md0
[root@linux ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Thu Oct 20 14:40:14 2022
        Raid Level : raid10
        Array Size : 41908224 (39.97 GiB 42.91 GB)
     Used Dev Size : 20954112 (19.98 GiB 21.46 GB)
      Raid Devices : 4
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Thu Oct 20 15:20:31 2022
             State : clean, degraded 
    Active Devices : 3
   Working Devices : 3
    Failed Devices : 1
     Spare Devices : 0
            Layout : near=2
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : d9eb6af0:515bcea2:ee3cb41b:895a3b3f
            Events : 30
    Number   Major   Minor   RaidDevice State
       -       0        0        0      removed
       1       8       32        1      active sync set-B   /dev/sdc
       2       8       48        2      active sync set-A   /dev/sdd
       3       8       64        3      active sync set-B   /dev/sde
       0       8       16        -      faulty   /dev/sdb

当RAID 1 磁盘阵列中存在一个故障盘时并不影响RAID10 磁盘阵列的使用。当购买了新的硬盘设备后再使用mdadm 命令来予以替换,重启系统,然后再把新的硬盘添加到RAID 磁盘阵列中,此sdb并不是损坏的那个盘

[root@linux ~]# umount /RAID
[root@linux ~]# mdadm /dev/md0 -a /dev/sdb
[root@linux ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Thu Oct 20 14:40:14 2022
        Raid Level : raid10
        Array Size : 41908224 (39.97 GiB 42.91 GB)
     Used Dev Size : 20954112 (19.98 GiB 21.46 GB)
      Raid Devices : 4
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Thu Oct 20 14:43:43 2022
             State : clean 
    Active Devices : 4
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 0
            Layout : near=2
        Chunk Size : 512K
Consistency Policy : resync
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : d9eb6af0:515bcea2:ee3cb41b:895a3b3f
            Events : 28
    Number   Major   Minor   RaidDevice State
       4       8       16        0      active sync set-A   /dev/sdb
       1       8       32        1      active sync set-B   /dev/sdc
       2       8       48        2      active sync set-A   /dev/sdd
       3       8       64        3      active sync set-B   /dev/sde
[root@linux ~]# mount -a
[root@linux ~]# reboot

磁盘阵列+备份盘

重置环境,建议打快照,利用部署RAID 5 磁盘阵列,防止磁盘全部损坏无法修复问题,至少需要用到3 块硬盘,还需要再加一块备份硬盘,总计需要在虚拟机中模拟4 块硬盘设备(和RAID 10一样的配置)创建一个RAID 5 磁盘阵列+备份盘

image.png

参数-n 3 代表创建RAID 5 磁盘阵列所需的硬盘数

参数-l 5 代表RAID 的级别

参数-x 1 则代表有一块备份盘

[root@linux ~]# mdadm -Cv /dev/md0 -n 3 -l 5 -x 1 /dev/sdb /dev/sdc /dev/sdd /dev/sde
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: size set to 20954112K
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
[root@linux ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Thu Oct 20 16:13:53 2022
        Raid Level : raid5
        Array Size : 41908224 (39.97 GiB 42.91 GB)
     Used Dev Size : 20954112 (19.98 GiB 21.46 GB)
      Raid Devices : 3
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Thu Oct 20 16:14:20 2022
             State : clean, degraded, recovering 
    Active Devices : 2
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 2
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
    Rebuild Status : 29% complete
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : 2d812a99:5ad53ed0:2155c63a:c2891922
            Events : 5
    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       4       8       48        2      spare rebuilding   /dev/sdd
       3       8       64        -      spare   /dev/sde

将部署好的RAID 5 磁盘阵列格式化为ext4 文件格式并挂载到目录

[root@linux ~]# mkfs.ext4 /dev/md0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=128 blocks, Stripe width=256 blocks
2621440 inodes, 10477056 blocks
523852 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2157969408
320 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
Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done   
[root@linux ~]# echo "/dev/md0 /RAID ext4 defaults 0 0" >> /etc/fstab
[root@linux ~]# mkdir /RAID
[root@linux ~]# mount -a
[root@linux ~]# reboot

模拟磁盘损坏,把硬盘设备/dev/sdb 移出磁盘阵列,迅速查看/dev/md0 磁盘阵列的状态,就会发现备份盘已经被自动顶替上去并开始数据同步,一定要做备份盘!

[root@linux ~]# mdadm /dev/md0 -f /dev/sdb
mdadm: set /dev/sdb faulty in /dev/md0
[root@linux ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Thu Oct 20 16:13:53 2022
        Raid Level : raid5
        Array Size : 41908224 (39.97 GiB 42.91 GB)
     Used Dev Size : 20954112 (19.98 GiB 21.46 GB)
      Raid Devices : 3
     Total Devices : 4
       Persistence : Superblock is persistent
       Update Time : Thu Oct 20 16:17:08 2022
             State : active, degraded, recovering 
    Active Devices : 2
   Working Devices : 3
    Failed Devices : 1
     Spare Devices : 1
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
    Rebuild Status : 11% complete
              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : 2d812a99:5ad53ed0:2155c63a:c2891922
            Events : 26
    Number   Major   Minor   RaidDevice State
       3       8       64        0      spare rebuilding   /dev/sde
       1       8       32        1      active sync   /dev/sdc
       4       8       48        2      active sync   /dev/sdd
       0       8       16        -      faulty   /dev/sdb

LVM

LVM 可以允许用户对硬盘资源进行动态调,LVM 技术是在硬盘分区和文件系统之间添加了一个逻辑层相,DAID如果是鸡蛋放篮子,LVM是单个鸡蛋打散之后都用来干啥,首先需要把这些鸡蛋(物理卷[PV,Physical Volume])打散到碗里(卷组[VG,Volume Group]),然后再把这个蛋液分成几份用来炒菜或者做鸡蛋糕(逻辑卷[LV,Logical Volume]),而且每个份的重量必须是按克数称重,防止不均(基本单元[PE,Physical Extent])的倍数

image.png

部署逻辑卷

部署LVM 时,需要逐个配置物理卷、卷组和逻辑卷

image.png

部署操作步骤

image.png

1.添加的两块硬盘设备支持LVM 技术

[root@linux ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000cac32
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      616447      307200   83  Linux
/dev/sda2          616448     4810751     2097152   82  Linux swap / Solaris
/dev/sda3         4810752    41943039    18566144   83  Linux
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
[root@linux ~]# pvcreate /dev/sdb /dev/sdc
  Physical volume "/dev/sdb" successfully created.
  Physical volume "/dev/sdc" successfully created.

2.把两块硬盘设备加入到storage 卷组

[root@linux ~]# vgcreate storage /dev/sdb /dev/sdc
Volume group "storage" successfully created
[root@linux ~]# vgdisplay
  --- Volume group ---
  VG Name               storage
  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               39.99 GiB
  PE Size               4.00 MiB
  Total PE              10238
  Alloc PE / Size       0 / 0   
  Free  PE / Size       10238 / 39.99 GiB
  VG UUID               upPFx8-zqS0-QpFZ-fdN8-KD1W-af2C-VUrk39

3.切割出一个约为150MB 的逻辑卷设备

以容量为单位,所使用的参数为-L

以基本单元的个数为单位,所使用的参数为-l

每个基本单元的大小默认为4MB

如使用-l 37 可以生成一个大小为37×4MB=148MB的逻辑卷

[root@linux ~]# lvcreate -n vo -l 37 storage
Logical volume "vo" created
[root@linux ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/storage/vo
  LV Name                vo
  VG Name                storage
  LV UUID                JC1hOS-eRNs-zcjp-zIWL-54Wp-zS4B-XIT3Pc
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2022-10-20 16:24:42 +0800
  LV Status              available
  # open                 0
  LV Size                148.00 MiB
  Current LE             37
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

4.生成好的逻辑卷进行格式化再挂载使用

[root@linux ~]# mkfs.ext4 /dev/storage/vo
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
38000 inodes, 151552 blocks
7577 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=33816576
19 block groups
8192 blocks per group, 8192 fragments per group
2000 inodes per group
Superblock backups stored on blocks: 
  8193, 24577, 40961, 57345, 73729
Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done 
[root@linux ~]# mkdir /linux
[root@linux ~]# mount /dev/storage/vo /linux

5.查看挂载状态,并写入到配置文件,使其永久生效

[root@localhost ~]# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/sda3                18G  5.6G   13G  32% /
devtmpfs                472M     0  472M   0% /dev
tmpfs                   488M     0  488M   0% /dev/shm
tmpfs                   488M  8.6M  479M   2% /run
tmpfs                   488M     0  488M   0% /sys/fs/cgroup
/dev/sda1               297M  138M  160M  47% /boot
tmpfs                    98M  4.0K   98M   1% /run/user/42
tmpfs                    98M   32K   98M   1% /run/user/1001
/dev/sr0                4.2G  4.2G     0 100% /run/media/weihongbin/CentOS 7 x86_64
/dev/mapper/storage-vo  140M  1.6M  128M   2% /linux

扩容逻辑卷

只要卷组中有足够的资源,就可以一直为逻辑卷扩容,扩展前一定要记得卸载设备和挂载点的关联

[root@localhost ~]# umount /linux

1.逻辑卷vo 扩展至290MB

[root@localhost ~]# lvextend -L 290M /dev/storage/vo
  Rounding size to boundary between physical extents: 292.00 MiB.
  Size of logical volume storage/vo changed from 148.00 MiB (37 extents) to 292.00 MiB (73 extents).
  Logical volume storage/vo successfully resized.

2.检查硬盘完整性,并重置硬盘容量

[root@localhost ~]# e2fsck -f /dev/storage/vo
e2fsck 1.42.9 (28-Dec-2013)
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/storage/vo: 11/38000 files (0.0% non-contiguous), 10453/151552 blocks
[root@localhost ~]# resize2fs /dev/storage/vo
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/storage/vo to 299008 (1k) blocks.
The filesystem on /dev/storage/vo is now 299008 blocks long.

3.重新挂载硬盘设备并查看挂载状态

[root@localhost ~]# mount /dev/storage/vo /linux
[root@localhost ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        18G  5.6G   13G  32% /
devtmpfs        472M     0  472M   0% /dev
tmpfs           488M     0  488M   0% /dev/shm
tmpfs           488M  8.6M  479M   2% /run
tmpfs           488M     0  488M   0% /sys/fs/cgroup
/dev/sda1       297M  138M  160M  47% /boot
tmpfs            98M  4.0K   98M   1% /run/user/42
tmpfs            98M   32K   98M   1% /run/user/1001
/dev/sr0        4.2G  4.2G     0 100% /run/media/weihongbin/CentOS 7 x86_64
/dev/mapper/storage-vo  279M  2.1M  259M   1% /linux

缩小逻辑卷

相较于扩容逻辑卷,在对逻辑卷进行缩容操作时,其丢失数据的风险更大,生产环境中执行相应操作时,一定要提前备份好数据,先检查文件系统的完整性,执行缩容操作前记得先把文件系统卸载掉

[root@localhost ~]# umount /linux

1.检查文件系统完整性

[root@localhost ~]# e2fsck -f /dev/storage/vo
e2fsck 1.42.9 (28-Dec-2013)
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/storage/vo: 11/74000 files (0.0% non-contiguous), 15507/299008 blocks

2.逻辑卷vo 的容量减小到120MB

[root@localhost ~]# resize2fs /dev/storage/vo 120M
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/storage/vo to 122880 (1k) blocks.
The filesystem on /dev/storage/vo is now 122880 blocks long.

3.重新挂载文件系统并查看系统状态

[root@localhost ~]# mount /dev/storage/vo /linux
[root@localhost ~]# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/sda3                18G  5.6G   13G  32% /
devtmpfs                472M     0  472M   0% /dev
tmpfs                   488M     0  488M   0% /dev/shm
tmpfs                   488M  8.6M  479M   2% /run
tmpfs                   488M     0  488M   0% /sys/fs/cgroup
/dev/sda1               297M  138M  160M  47% /boot
tmpfs                    98M  4.0K   98M   1% /run/user/42
tmpfs                    98M   32K   98M   1% /run/user/1001
/dev/sr0                4.2G  4.2G     0 100% /run/media/weihongbin/CentOS 7 x86_64
/dev/mapper/storage-vo  113M  1.6M  103M   2% /linux

逻辑卷快照

LVM 的快照卷功能有两个特点:

快照卷的容量必须等同于逻辑卷的容量

快照卷仅一次有效,一旦执行还原操作后则会被立即自动删除

查看卷组的信息

[root@localhost ~]# vgdisplay
  --- Volume group ---
  VG Name               storage
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               39.99 GiB
  PE Size               4.00 MiB
  Total PE              10238
  Alloc PE / Size       73 / 292.00 MiB
  Free  PE / Size       10165 / <39.71 GiB
  VG UUID               upPFx8-zqS0-QpFZ-fdN8-KD1W-af2C-VUrk39

来用重定向往逻辑卷设备所挂载的目录中写入一个文件

[root@localhost ~]# echo "kuaizhao" > /linux/readme.txt
[root@localhost ~]# ll /linux/
total 13
drwx------ 2 root root 12288 Oct 20 16:25 lost+found
-rw-r--r-- 1 root root     9 Oct 20 16:45 readme.txt

1.生成快照

-s 参数生成一个快照卷

-L 参数指定切割的大小

[root@localhost ~]# lvcreate -L 120M -s -n SNAP /dev/storage/vo
  Logical volume "SNAP" created.
[root@localhost ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/storage/vo
  LV Name                vo
  VG Name                storage
  LV UUID                JC1hOS-eRNs-zcjp-zIWL-54Wp-zS4B-XIT3Pc
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2022-10-20 16:24:42 +0800
  LV snapshot status     source of
                         SNAP [active]
  LV Status              available
  # open                 1
  LV Size                292.00 MiB
  Current LE             73
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
    --- Logical volume ---
  LV Path                /dev/storage/SNAP
  LV Name                SNAP
  VG Name                storage
  LV UUID                dFeWto-cMYA-eKLz-YyNc-401y-V3vC-gj8CgK
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2022-10-20 16:49:42 +0800
  LV snapshot status     active destination for vo
  LV Status              available
  # open                 0
  LV Size                292.00 MiB
  Current LE             73
  COW-table size         120.00 MiB
  COW-table LE           30
  Allocated to snapshot  0.01%
  Snapshot chunk size    4.00 KiB
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:3

2.逻辑卷所挂载的目录中创建一个100MB 的垃圾文件,查看快照卷的状态

[root@localhost ~]# dd if=/dev/zero of=/linux/files count=1 bs=100M
1+0 records in
1+0 records out
104857600 bytes (105 MB) copied, 0.480484 s, 218 MB/s
[root@localhost ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/storage/vo
  LV Name                vo
  VG Name                storage
  LV UUID                JC1hOS-eRNs-zcjp-zIWL-54Wp-zS4B-XIT3Pc
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2022-10-20 16:24:42 +0800
  LV snapshot status     source of
                         SNAP [active]
  LV Status              available
  # open                 1
  LV Size                292.00 MiB
  Current LE             73
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
  --- Logical volume ---
  LV Path                /dev/storage/SNAP
  LV Name                SNAP
  VG Name                storage
  LV UUID                dFeWto-cMYA-eKLz-YyNc-401y-V3vC-gj8CgK
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2022-10-20 16:49:42 +0800
  LV snapshot status     active destination for vo
  LV Status              available
  # open                 0
  LV Size                292.00 MiB
  Current LE             73
  COW-table size         120.00 MiB
  COW-table LE           30
  Allocated to snapshot  83.71%
  Snapshot chunk size    4.00 KiB
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:3

3.校验SNAP 快照卷的效果,卸载掉逻辑卷设备与目录的挂载

[root@localhost ~]# umount /linux
[root@localhost ~]# lvconvert --merge /dev/storage/SNAP
  Merging of volume storage/SNAP started.
  storage/vo: Merged: 100.00%

4.快照卷会被自动删除掉,在逻辑卷设备被执行快照操作后再创建出来的100MB 的垃圾文件也被清除

[root@localhost ~]# mount /dev/storage/vo /linux
[root@localhost ~]# ll /linux/
total 13
drwx------ 2 root root 12288 Oct 20 16:25 lost+found
-rw-r--r-- 1 root root     9 Oct 20 16:45 readme.txt

删除逻辑卷

执行LVM 的删除操作,提前备份好重要的数据信息,然后依次删除逻辑卷、卷组、物理卷设备,顺序不可颠倒

1.取消逻辑卷与目录的挂载关联,删除配置文件中永久生效的设备参数

[root@localhost ~]# umount /linux
[root@localhost ~]# vim /etc/fstab
#
# /etc/fstab
# Created by anaconda on Mon Aug  8 19:10:01 2022
#
# 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
#
UUID=fcea37da-6287-42e5-9e6f-a08000a539ae /                       xfs     defaults        0 0
UUID=8abbad7c-2fce-46bd-b886-1c350b525f42 /boot                   xfs     defaults        0 0
UUID=c1b4b7cd-7aa5-48a3-bd8e-afd715762383 swap                    swap    defaults        0 0

2.删除逻辑卷设

[root@localhost ~]# lvremove /dev/storage/vo
Do you really want to remove active logical volume storage/vo? [y/n]: y
  Logical volume "vo" successfully removed

3.删除卷组

[root@localhost ~]# vgremove storage
  Volume group "storage" successfully removed

4.删除物理卷设备

[root@localhost ~]# pvremove /dev/sdb /dev/sdc
  Labels on physical volume "/dev/sdb" successfully wiped.
  Labels on physical volume "/dev/sdc" successfully wiped.

5.检验查看LVM 的信息时就不会再看到信息

[root@localhost ~]# pvdisplay
[root@localhost ~]# vgdisplay
[root@localhost ~]# lvdisplay

结语

简问简答

RAID 技术主要是为了解决什么问题呢?

答:RAID 技术可以解决存储设备的读写速度问题及数据的冗余备份问题


位于LVM 最底层的是物理卷还是卷组?

答:最底层的是物理卷,然后在通过物理卷组成卷组


LVM 的快照卷能使用几次?

答:只可使用一次,而且使用后即自动删除


LVM 的删除顺序是怎么样的?

答:依次移除逻辑卷、卷组和物理卷

如果想根据教程实践的朋友们可以通过阿里云ecs服务器免费试用和低价购买,入口如下

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