Raid 5 （软raid）创建、模拟损坏、移除、添加新磁盘的实验

1.查看磁盘分区，做raid5 最少需要3块盘

磁盘 /dev/sdb：1073 MB, 1073741824 字节，2097152 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0x71dbe158
   设备 Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048      206847      102400   83  Linux
/dev/sdb2          206848      411647      102400   83  Linux
/dev/sdb3          411648      616447      102400   83  Linux

2.用mdadm 命令创建raid5 阵列

[root@bogon ~]# mdadm -C /dev/md5 -n3 -l5 /dev/sdb{1,2,3}
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.

3.查看raid5阵列信息，可以看到我们的raid5 已经创建完毕

[root@bogon ~]# mdadm -D /dev/md5 
/dev/md5:
           Version : 1.2
     Creation Time : Wed Jun 12 22:38:30 2019
        Raid Level : raid5
        Array Size : 200704 (196.00 MiB 205.52 MB)
     Used Dev Size : 100352 (98.00 MiB 102.76 MB)
      Raid Devices : 3
     Total Devices : 3
       Persistence : Superblock is persistent

       Update Time : Wed Jun 12 22:38:32 2019
             State : clean 
    Active Devices : 3
   Working Devices : 3
    Failed Devices : 0
     Spare Devices : 0

            Layout : left-symmetric
        Chunk Size : 512K

Consistency Policy : resync

              Name : bogon:5  (local to host bogon)
              UUID : 4b0810bc:460a99c0:9d06b842:8ebfcad9
            Events : 18
Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       18        1      active sync   /dev/sdb2
       3       8       19        2      active sync   /dev/sdb3

4.对其创建文件系统，在这里我选择的是xfs格式，并进行挂载操作

[root@bogon ~]# mkfs.xfs /dev/md5 
meta-data=/dev/md5               isize=512    agcount=8, agsize=6272 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=50176, imaxpct=25
         =                       sunit=128    swidth=256 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=624, version=2
         =                       sectsz=512   sunit=8 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

挂载

[root@bogon ~]# mount /dev/md5 /mnt/disk1/

查看挂载是否成功

[root@bogon ~]# df -Th
文件系统                类型      容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root xfs        17G  4.5G   13G   27% /
devtmpfs                devtmpfs  470M     0  470M    0% /dev
tmpfs                   tmpfs     487M     0  487M    0% /dev/shm
tmpfs                   tmpfs     487M  8.6M  478M    2% /run
tmpfs                   tmpfs     487M     0  487M    0% /sys/fs/cgroup
/dev/sda1               xfs      1014M  166M  849M   17% /boot
tmpfs                   tmpfs      98M  8.0K   98M    1% /run/user/42
tmpfs                   tmpfs      98M   28K   98M    1% /run/user/0
/dev/sr0                iso9660   4.3G  4.3G     0  100% /run/media/root/CentOS 7 x86_64
/dev/md5                xfs       194M   11M  184M    6% /mnt/disk1

5.模拟磁盘损坏

[root@bogon ~]# mdadm -f /dev/md5 /dev/sdb3
mdadm: set /dev/sdb3 faulty in /dev/md5

查看raid5信息

[root@bogon ~]# mdadm -D /dev/md5 
/dev/md5:
           Version : 1.2
     Creation Time : Wed Jun 12 22:38:30 2019
        Raid Level : raid5
        Array Size : 200704 (196.00 MiB 205.52 MB)
     Used Dev Size : 100352 (98.00 MiB 102.76 MB)
      Raid Devices : 3
     Total Devices : 3
       Persistence : Superblock is persistent

       Update Time : Wed Jun 12 22:51:07 2019
             State : clean, degraded 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 1
     Spare Devices : 0

            Layout : left-symmetric
        Chunk Size : 512K

Consistency Policy : resync

              Name : bogon:5  (local to host bogon)
              UUID : 4b0810bc:460a99c0:9d06b842:8ebfcad9
            Events : 20
    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       18        1      active sync   /dev/sdb2
       -       0        0        2      removed

       3       8       19        -      faulty   /dev/sdb3

移除损坏磁盘，我们可以看到sdb3 已经从raid5中移除了

[root@bogon ~]# mdadm -r /dev/md5 /dev/sdb3
mdadm: hot removed /dev/sdb3 from /dev/md5

 Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       18        1      active sync   /dev/sdb2
       -       0        0        2      removed

6.添加新的额磁盘，并查看

[root@bogon ~]# mdadm -a /dev/md5 /dev/sdb3
mdadm: added /dev/sdb3

raid5中，出现了我们添加的sdb3

 Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       18        1      active sync   /dev/sdb2
       3       8       19        2      active sync   /dev/sdb3