Linux巩固篇007-Linux 磁盘阵列技术
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
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
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
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
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
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]
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
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
部署逻辑卷
部署LVM 时，需要逐个配置物理卷、卷组和逻辑卷
部署操作步骤
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