RHEL 7 RARHEL 7 RAID 5 （软）实验 磁盘阵列 ID 5 （软）实验 磁盘阵列

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一、模拟磁盘设备
[iyunv@localhost ~]# ls /dev/sd*   # 查看添加的硬件----磁盘设备
/dev/sda  /dev/sda1  /dev/sda2  /dev/sdb  /dev/sdc
[iyunv@localhost ~]# fdisk /dev/sdb # 分区 模拟出4块硬盘

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): # 默认
First sector (2048-20971519, default 2048): #默认
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1G # 添加1G
Partition 1 of type Linux and of size 1 GiB is set

操作同上共分了四个区  /dev/sdb{1,2,3,4}  当做四块硬盘使用

Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 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: 0x0e220a08
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     2099199     1048576   83  Linux
/dev/sdb2         2099200     4196351     1048576   83  Linux
/dev/sdb3         4196352     6293503     1048576   83  Linux
/dev/sdb4         6293504     8390655     1048576   83  Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[iyunv@localhost ~]# fdisk /dev/sdc  # 分区模拟出4块硬盘

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):
First sector (2048-20971519, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1G
Partition 1 of type Linux and of size 1 GiB is set

同上 分四个区 /dev/sdc{1,2,3,4} 当做4块硬盘使用
   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048     2099199     1048576   83  Linux
/dev/sdc2         2099200     4196351     1048576   83  Linux
/dev/sdc3         4196352     6293503     1048576   83  Linux
/dev/sdc4         6293504     8390655     1048576   83  Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[iyunv@localhost ~]# ls /dev/sd*
/dev/sda   /dev/sda2  /dev/sdb1  /dev/sdb3  /dev/sdc   /dev/sdc2  /dev/sdc4
/dev/sda1  /dev/sdb   /dev/sdb2  /dev/sdb4  /dev/sdc1  /dev/sdc3

二、创建RAID 5
mdadm 命令

选项

    -C 创建软RAID
    -l 指定RAID级别
    -n 指定磁盘的个数
    -x 指定备用设备的个数
    -a 添加磁盘
    -r 移除磁盘（热）
    -v 显示详细信息
    -s 扫描配置文件
    -S 停止阵列 释放
    -A 激活，加载 Assemble
    -f 设为故障盘
     
[iyunv@localhost ~]# mdadm -C /dev/md5 -l 5 -n 3 -x 1 /dev/sdb{1,2,3,4}  # 创建raid 5
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.
[iyunv@localhost ~]# mdadm -D /dev/md5
/dev/md5:
        Version : 1.2
  Creation Time : Sun Jun 19 21:00:53 2016
     Raid Level : raid5
     Array Size : 2095104 (2046.34 MiB 2145.39 MB)
  Used Dev Size : 1047552 (1023.17 MiB 1072.69 MB)
   Raid Devices : 3
  Total Devices : 4
    Persistence : Superblock is persistent
    Update Time : Sun Jun 19 21:00:59 2016
          State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
  Spare Devices : 1
         Layout : left-symmetric
     Chunk Size : 512K
           Name : localhost.localdomain:5  (local to host localhost.localdomain)
           UUID : 467e61c9:1ddfd1c6:51c27a22:bb7d160c
         Events : 18
    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       18        1      active sync   /dev/sdb2
       4       8       19        2      active sync   /dev/sdb3
       3       8       20        -      spare   /dev/sdb4
[iyunv@localhost ~]# ls /dev/md*
/dev/md5

[iyunv@localhost ~]# fdisk /dev/md5



    Device Boot      Start         End      Blocks   Id  System
/dev/md5p1            2048     2099199     1048576   83  Linux
/dev/md5p2         2099200     4190207     1045504   83  Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.


[iyunv@localhost ~]# mkfs.xfs /dev/md5p1 && mkfs.xfs /dev/md5p2

[iyunv@localhost ~]# echo $?
0
[iyunv@localhost ~]# mkdir /opt/raid{5_1,5_2}

[iyunv@localhost ~]# blkid /dev/md*
/dev/md5: PTTYPE="dos"
/dev/md5p1: UUID="f1354f72-bbe5-4364-9ade-576d95d4c812" TYPE="xfs"
/dev/md5p2: UUID="d403dca4-6f77-411e-a519-b0536a8867e7" TYPE="xfs"
[iyunv@localhost ~]# echo "UUID="f1354f72-bbe5-4364-9ade-576d95d4c812" /opt/raid5_1 xfs defaults 0 0" >> /etc/fstab
[iyunv@localhost ~]# echo "UUID="d403dca4-6f77-411e-a519-b0536a8867e7" /opt/raid5_2 xfs defaults 0 0" >> /etc/fstab
[iyunv@localhost ~]# tail -3 !$
tail -3 /etc/fstab
/dev/sr0 /mnt iso9660 defaults 0 0
UUID=f1354f72-bbe5-4364-9ade-576d95d4c812 /opt/raid5_1 xfs defaults 0 0
UUID=d403dca4-6f77-411e-a519-b0536a8867e7 /opt/raid5_2 xfs defaults 0 0
[iyunv@localhost ~]# mount -a
[iyunv@localhost ~]# cp /etc/passwd /opt/raid5_1
[iyunv@localhost ~]# cp /etc/passwd /opt/raid5_2
[iyunv@localhost ~]# cp -r /etc /opt/raid5_1
[iyunv@localhost ~]# cp -r /etc /opt/raid5_2
[iyunv@localhost ~]# ls /opt/raid*
/opt/raid5_1:
etc  passwd
/opt/raid5_2:
etc  passwd
[iyunv@localhost ~]# echo "DEVICES /dev/sdb1 /dev/sdb2 /dev/sdb3 /dev/sdb4" >> /etc/mdadm.conf
[iyunv@localhost ~]# mdadm -Evs >> /etc/mdadm.conf
[iyunv@localhost ~]# mount -a
[iyunv@localhost ~]# tail -3 /etc/fstab
/dev/sr0 /mnt iso9660 defaults 0 0
UUID=f1354f72-bbe5-4364-9ade-576d95d4c812 /opt/raid5_1 xfs defaults 0 0
UUID=d403dca4-6f77-411e-a519-b0536a8867e7 /opt/raid5_2 xfs defaults 0 0
[iyunv@localhost ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on

/dev/md5p1            1018M   68M  951M   7% /opt/raid5_1
/dev/md5p2            1018M   68M  951M   7% /opt/raid5_2
[iyunv@localhost ~]#

三、Raid 性能测试  （RAID 5 写入速度比普通磁盘块）

[iyunv@localhost ~]# time dd if=/dev/zero of=txt bs=1M count=20

real    0m0.197s
user    0m0.001s
sys 0m0.180s
[iyunv@localhost ~]# cd /opt/raid5_1
[iyunv@localhost raid5_1]# time dd if=/dev/zero of=txt bs=1M count=20

real    0m0.102s
user    0m0.000s
sys 0m0.033s

四、RAID 故障模拟
[iyunv@localhost ~]# mdadm /dev/md5 -f /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md5

此时可以动态查看一下
[iyunv@localhost ~]# watch -n 1 cat /proc/mdstat

[iyunv@localhost ~]# mdadm --detail /dev/md5
/dev/md5:
        Version : 1.2
  Creation Time : Sun Jun 19 21:00:53 2016
     Raid Level : raid5
     Array Size : 2095104 (2046.34 MiB 2145.39 MB)
  Used Dev Size : 1047552 (1023.17 MiB 1072.69 MB)
   Raid Devices : 3
  Total Devices : 4
    Persistence : Superblock is persistent

    Update Time : Sun Jun 19 22:43:16 2016
          State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : localhost.localdomain:5  (local to host localhost.localdomain)
           UUID : 467e61c9:1ddfd1c6:51c27a22:bb7d160c
         Events : 37

    Number   Major   Minor   RaidDevice State
       3       8       20        0      active sync   /dev/sdb4
       1       8       18        1      active sync   /dev/sdb2
       4       8       19        2      active sync   /dev/sdb3

       0       8       17        -      faulty   /dev/sdb1
        
        
[iyunv@localhost ~]# mdadm -r /dev/md5 /dev/sdb1
mdadm: hot removed /dev/sdb1 from /dev/md5
[iyunv@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdb2[1] sdb3[4] sdb4[3]
      2095104 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
      
unused devices: <none>


[iyunv@localhost ~]# mdadm -a /dev/md5 /dev/sdc1
mdadm: added /dev/sdc1
[iyunv@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdc1[5](S) sdb2[1] sdb3[4] sdb4[3]
      2095104 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
      
unused devices: <none>
[iyunv@localhost ~]# diff /etc/passwd /opt/raid5_1/passwd
[iyunv@localhost ~]# echo "DEVICE /dev/sdb2 /dev/sdb3 /dev/sdb4 /dev/sdc1" > /etc/mdadm.conf
[iyunv@localhost ~]# mdadm -Evs >> !$
mdadm -Evs >> /etc/mdadm.conf

五、删除RAID设备

[iyunv@localhost ~]# umount /opt/raid5_1
[iyunv@localhost ~]# umount /opt/raid5_2
[iyunv@localhost ~]# mdadm -Ss
[iyunv@localhost ~]# rm -rf /etc/mdadm.conf
[iyunv@localhost ~]# rm -rf /opt/raid5_1
[iyunv@localhost ~]# rm -rf /opt/raid5_2
[iyunv@localhost ~]# vim /etc/fstab   #删除开机RAID挂载项  
[iyunv@localhost ~]# mdadm --misc --zero-superblock /dev/sdb1
[iyunv@localhost ~]# mdadm --misc --zero-superblock /dev/sdb2
[iyunv@localhost ~]# mdadm --misc --zero-superblock /dev/sdb3
[iyunv@localhost ~]# mdadm --misc --zero-superblock /dev/sdb4
[iyunv@localhost ~]# mdadm --misc --zero-superblock /dev/sdc1
[iyunv@localhost ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   10G  3.2G  6.9G  32% /
devtmpfs               898M     0  898M   0% /dev
tmpfs                  913M   84K  913M   1% /dev/shm
tmpfs                  913M  8.9M  904M   1% /run
tmpfs                  913M     0  913M   0% /sys/fs/cgroup
/dev/sr0               3.8G  3.8G     0 100% /mnt
/dev/sda1              497M  158M  340M  32% /boot
tmpfs                  183M   16K  183M   1% /run/user/42
tmpfs                  183M     0  183M   0% /run/user/0
[iyunv@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
unused devices: <none>
[iyunv@localhost ~]# mdadm --detail /dev/md5
mdadm: cannot open /dev/md5: No such file or directory