CentOS7.3实现软RAID-10

独立硬盘冗余阵列（RAID, Redundant Array of Independent Disks），旧称廉价磁盘冗余阵列（Redundant Array of Inexpensive Disks），简称磁盘阵列。其基本思想就是把多个相对便宜的硬盘组合起来，成为一个硬盘阵列组，使性能达到甚至超过一个价格昂贵、容量巨大的硬盘。根据选择的版本不同，RAID比单颗硬盘有以下一个或多个方面的好处：增强数据集成度，增强容错功能，增加处理量或容量。另外，磁盘阵列对于电脑来说，看起来就像一个单独的硬盘或逻辑存储单元。分为RAID-0，RAID-1，RAID-1E，RAID-5，RAID-6，RAID-7，RAID-10，RAID-50，RAID-60。—— [RAID - 维基百科]

• 实现方式：
  • 外接式磁盘阵列：通过扩展卡提供适配能力
  • 内接式RAID：主板集成RAID控制器
  • 软件RAID：通过OS实现

• 实验内容：用虚拟机CentOS 7.3实现软RAID-10

• 实验条件：CentOS7.3虚拟机，添加四块硬盘

• 实验命令：

• mdadm [mode] <raiddevice> [options] <component-devices

模式	主要功能	选项
Create	使用空闲的设备创建一个新的阵列，每个设备具有元数据块	-C
Manage	管理已经存储阵列中的设备	-f, -r, -a

1、lsblk查看当前硬盘分区情况

可以看到sdb、sdc、sdd、sde未使用

[root@CentOS7 ~]#lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  200G  0 disk 
├─sda1   8:1    0    1G  0 part /boot
├─sda2   8:2    0 97.7G  0 part /
├─sda3   8:3    0 48.8G  0 part /app
├─sda4   8:4    0    1K  0 part 
├─sda5   8:5    0    2G  0 part [SWAP]
└─sda6   8:6    0   10G  0 part /home
sdb      8:16   0   50G  0 disk 
sdc      8:32   0   50G  0 disk 
sdd      8:48   0   50G  0 disk 
sde      8:64   0   40G  0 disk 
sr0     11:0    1  7.7G  0 rom  

2、分区

由于RAID要求每块硬盘大小相同，而sde大小为40G，其他三块硬盘为50G。因此分别对sdb、sdc、sdd、sde划分分区，每个硬盘划分一个40G的分区，并修改Hex code为fd。

[root@CentOS7 ~]#fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x74a61da7.

Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-104857599, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-104857599, default 104857599): +40G
Partition 1 of type Linux and of size 40 GiB is set

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): p

Disk /dev/sdb: 53.7 GB, 53687091200 bytes, 104857600 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: 0x74a61da7

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    83888127    41943040   fd  Linux raid autodetect

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

其他硬盘分区 过程略，分区后如下：

[root@CentOS7 ~]#lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  200G  0 disk 
├─sda1   8:1    0    1G  0 part /boot
├─sda2   8:2    0 97.7G  0 part /
├─sda3   8:3    0 48.8G  0 part /app
├─sda4   8:4    0    1K  0 part 
├─sda5   8:5    0    2G  0 part [SWAP]
└─sda6   8:6    0   10G  0 part /home
sdb      8:16   0   50G  0 disk 
└─sdb1   8:17   0   40G  0 part 
sdc      8:32   0   50G  0 disk 
└─sdc1   8:33   0   40G  0 part 
sdd      8:48   0   50G  0 disk 
└─sdd1   8:49   0   40G  0 part 
sde      8:64   0   40G  0 disk 
└─sde1   8:65   0   40G  0 part 
sr0     11:0    1  7.7G  0 rom  

3、创建RAID-1

sdb1、sdc1组成一组RAID-1，RAID设备名为/dev/md0

[root@CentOS7 sys]#mdadm -C /dev/md0 -a yes -l 1 -n 2 /dev/sd{c1,b1}
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
Continue creating array? yes
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

sdd1、sde1组成一组RAID-1，RAID设备名为/dev/md1

[root@CentOS7 sys]#mdadm -C /dev/md1 -a yes -l 1 -n 2 /dev/sdd1 /dev/sde1
...略

查看进度：

[root@CentOS7 sys]#cat /proc/mdstat
Personalities : [raid1] 
md1 : active raid1 sde1[1] sdd1[0]
      41909248 blocks super 1.2 [2/2] [UU]
      [======>..............]  resync = 32.9% (13801472/41909248) finish=2.2min speed=205884K/sec
      
md0 : active raid1 sdb1[1] sdc1[0]
      41910272 blocks super 1.2 [2/2] [UU]

查看RAID信息：

[root@CentOS7 sys]#mdadm -D /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Mon Jun 26 20:22:24 2017
     Raid Level : raid1
     Array Size : 41910272 (39.97 GiB 42.92 GB)
  Used Dev Size : 41910272 (39.97 GiB 42.92 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Mon Jun 26 20:25:54 2017
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : CentOS7.LMJ.com:0  (local to host CentOS7.LMJ.com)
           UUID : 3d852350:c70e388a:ea33f443:37b1e32c
         Events : 17

    Number   Major   Minor   RaidDevice State
       0       8       33        0      active sync   /dev/sdc1
       1       8       17        1      active sync   /dev/sdb1

4、创建RAID-0

用/dev/md0和/dev/md1创建RAID-0：

[root@CentOS7 sys]#mdadm -C /dev/md2 -a yes -l 0 -n 2 /dev/md{0,1}
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md2 started.

5、生成配置文件

当raid重新启用时，会读取该配置文件

[root@CentOS7 sys]#mdadm -Ds /dev/md0 > /etc/mdadm.conf
[root@CentOS7 sys]#mdadm -Ds /dev/md1 >> /etc/mdadm.conf
[root@CentOS7 sys]#mdadm -Ds /dev/md2 >> /etc/mdadm.conf
[root@CentOS7 sys]#cat /etc/mdadm.conf 
ARRAY /dev/md0 metadata=1.2 name=CentOS7.LMJ.com:0 UUID=3d852350:c70e388a:ea33f443:37b1e32c
ARRAY /dev/md1 metadata=1.2 name=CentOS7.LMJ.com:1 UUID=3ee6e29f:84b58d88:f19ba866:fdc451fa
ARRAY /dev/md2 metadata=1.2 name=CentOS7.LMJ.com:2 UUID=d27e4a09:17b5b2c1:0e82eb95:5833b5aa

6、创建文件系统

[root@CentOS7 sys]#mkfs.ext4 /dev/md2

7、挂载

[root@CentOS7 sys]#mount /dev/md2 /mnt/raid
[root@CentOS7 sys]#df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2        98G  4.4G   94G   5% /
devtmpfs        474M     0  474M   0% /dev
tmpfs           489M   84K  489M   1% /dev/shm
tmpfs           489M   14M  475M   3% /run
tmpfs           489M     0  489M   0% /sys/fs/cgroup
/dev/sda6       9.8G  138M  9.1G   2% /home
/dev/sda3        49G   36M   49G   1% /app
/dev/sda1      1014M  169M  846M  17% /boot
tmpfs            98M   16K   98M   1% /run/user/42
tmpfs            98M     0   98M   0% /run/user/0
/dev/md2         79G   57M   75G   1% /mnt/raid
[root@CentOS7 ~]#lsblk
NAME      MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sda         8:0    0  200G  0 disk  
├─sda1      8:1    0    1G  0 part  /boot
├─sda2      8:2    0 97.7G  0 part  /
├─sda3      8:3    0 48.8G  0 part  /app
├─sda4      8:4    0    1K  0 part  
├─sda5      8:5    0    2G  0 part  [SWAP]
└─sda6      8:6    0   10G  0 part  /home
sdb         8:16   0   50G  0 disk  
└─sdb1      8:17   0   40G  0 part  
  └─md0     9:0    0   40G  0 raid1 
    └─md2   9:2    0 79.9G  0 raid0 
sdc         8:32   0   50G  0 disk  
└─sdc1      8:33   0   40G  0 part  
  └─md0     9:0    0   40G  0 raid1 
    └─md2   9:2    0 79.9G  0 raid0 
sdd         8:48   0   50G  0 disk  
└─sdd1      8:49   0   40G  0 part  
  └─md1     9:1    0   40G  0 raid1 
    └─md2   9:2    0 79.9G  0 raid0 
sde         8:64   0   40G  0 disk  
└─sde1      8:65   0   40G  0 part  
  └─md1     9:1    0   40G  0 raid1 
    └─md2   9:2    0 79.9G  0 raid0 
sr0        11:0    1  7.7G  0 rom