磁盘管理——RAID 1

喜欢ヅ旅行 2021-11-06 01:10 367阅读 0赞

## 一 什么是RAID1 ##

RAID1，可称为镜像，将数据写到多个磁盘，比如一组数据叫做 A，那么数据会这样存在：A、A ，这样数据安全性高，但性能不佳。

![20130811085353140][]

两组以上的N个磁盘相互作镜像，在一些多线程操作系统中能有很好的读取速度，另外写入速度有微小的降低。除非拥有相同资料的主磁碟与镜像同时损坏，否则只要一个磁盘正常即可维持运作，可靠性最高。RAID 1就是镜像。其原理为在主硬盘上存放数据的同时也在镜像硬盘上写一样的数据。当主硬盘（物理）损坏时，镜像硬盘则代替主硬盘的工作。因为有镜像硬盘做数据备份，所以RAID 1的数据安全性在所有的RAID级别上来说是最好的。但无论用多少磁碟做RAID 1，仅算一个磁碟的容量，是所有RAID上磁盘利用率最低的一个级别。

![20130811085401437][]

## 二 RAID1演示 ##

### 第一步 对磁盘进行分区 ###

#对/dev/sdb进行分区
    root@serv01 ~]# fdisk /dev/sdb
    #对/dev/sdc进行分区
    root@serv01 ~]# fdisk /dev/sdc
     
    [root@serv01 ~]# ls /dev/sdb
    sdb  sdb1 
    [root@serv01 ~]# ls /dev/sdc
    sdc  sdc1

### 第二步 制作RAID1 ###

[root@serv01 ~]# mdadm -C /dev/md1 -l 1 -n2 /dev/sdb1 /dev/sdc1
    mdadm: /dev/sdb1 appears to contain anext2fs file system
       size=208812K  mtime=Wed Jul 3122:17:43 2013
    mdadm: /dev/sdb1 appears to be part of araid array:
       level=raid0 devices=0 ctime=Thu Jan 1 07:00:00 1970
    mdadm: partition table exists on /dev/sdb1but will be lost or
          meaningless after creating array
    mdadm: Note: this array has metadata at thestart 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? y
    mdadm: Defaulting to version 1.2 metadata
    mdadm: array /dev/md1 started.
    #格式化
    [root@serv01 ~]# mkfs.ext4 /dev/md1
    mke2fs 1.41.12 (17-May-2010)
    Filesystem label=
    OS type: Linux
    Block size=4096 (log=2)
    Fragment size=4096 (log=2)
    Stride=0 blocks, Stripe width=0 blocks
    131072 inodes, 523853 blocks
    26192 blocks (5.00%) reserved for the superuser
    First data block=0
    Maximum filesystem blocks=536870912
    16 block groups
    32768 blocks per group, 32768 fragments pergroup
    8192 inodes per group
    Superblock backups stored on blocks:
           32768,98304, 163840, 229376, 294912
     
    Writing inode tables: done                           
    Creating journal (8192 blocks): done
    Writing superblocks and filesystemaccounting information: done
     
    This filesystem will be automaticallychecked every 36 mounts or
    180 days, whichever comes first.  Use tune2fs -c or -i to override.

### 第三步 挂载 ###

[root@serv01 ~]# mount /dev/md1 /web
    [root@serv01 ~]# cat /etc/fstab
     
    #
    # /etc/fstab
    # Created by anaconda on Tue Jul 2300:54:37 2013
    #
    # Accessible filesystems, by reference, aremaintained under '/dev/disk'
    # See man pages fstab(5), findfs(8),mount(8) and/or blkid(8) for more info
    #
    UUID=110fab7c-85c4-4bae-9114-98bc2ada24d8/                       ext4    defaults        1 1
    UUID=ab434325-bf02-48e9-8ce7-78494a8ac71e/boot                   ext4    defaults        1 2
    UUID=02ed2b3b-b7e1-493d-9a43-8e1dcac8aa6f/opt                    ext4    defaults        1 2
    UUID=a088a35a-16d8-456a-a177-95c769c16e41swap                    swap    defaults        0 0
    tmpfs                   /dev/shm                tmpfs   defaults        0 0
    devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
    sysfs                  /sys                    sysfs   defaults        0 0
    proc                    /proc                   proc    defaults        0 0

### 第四步 修改配置文件 ###

#追加内容到/etc/fstab文件
    [root@serv01 ~]# echo "/dev/md1 /webext4 defaults 1 2" >> /etc/fstab
    #再次查看文件内容
    [root@serv01 ~]# cat /etc/fstab
     
    #
    # /etc/fstab
    # Created by anaconda on Tue Jul 2300:54:37 2013
    #
    # Accessible filesystems, by reference, aremaintained under '/dev/disk'
    # See man pages fstab(5), findfs(8),mount(8) and/or blkid(8) for more info
    #
    UUID=110fab7c-85c4-4bae-9114-98bc2ada24d8/                       ext4    defaults        1 1
    UUID=ab434325-bf02-48e9-8ce7-78494a8ac71e/boot                   ext4    defaults        1 2
    UUID=02ed2b3b-b7e1-493d-9a43-8e1dcac8aa6f/opt                    ext4    defaults        1 2
    UUID=a088a35a-16d8-456a-a177-95c769c16e41swap                    swap    defaults        0 0
    tmpfs                   /dev/shm                tmpfs   defaults        0 0
    devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
    sysfs                   /sys                    sysfs   defaults        0 0
    proc                    /proc                   proc    defaults        0 0
    /dev/md1 /web ext4 defaults 1 2
    #创建mdadm.conf文件
    [root@serv01 ~]# mdadm --detail —scan >/etc/mdadm.conf

### 第五步 模拟硬盘坏掉 ###

#重启
    [root@serv01 ~]# reboot
    #拷贝内容
    [root@serv01 ~]# cp /boot/* /web/ -rvf
    #清除磁盘，o清除，然后保存
    [root@serv01 ~]# fdisk /dev/sdb
    #拷贝内容
    [root@serv01 ~]# cp /etc/* /web/ -rvf
          
    #重启
    [root@larrywen Desktop]# ssh 192.168.1.11
    root@192.168.1.11's password:
    Last login: Thu Aug  1 17:55:43 2013 from 192.168.1.1
    [root@serv01 ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdc1[1] sdb1[0]
         2095415 blocks super 1.2 [2/2] [UU]
         
    unused devices: <none>
     
    [root@larrywen Desktop]# ssh 192.168.1.11
    root@192.168.1.11's password:
    Last login: Thu Aug  1 18:05:58 2013 from 192.168.1.1
    #查看状态
    [root@serv01 ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdc1[1]
         2095415 blocks super 1.2 [2/1] [_U]
         
    unused devices: <none>
     
    [root@serv01 ~]# mdadm --detail /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 1
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:07:522013
             State : clean, degraded
     Active Devices : 1
    Working Devices : 1
     FailedDevices : 0
     Spare Devices : 0
     
              Name : serv01.host.com:1  (localto host serv01.host.com)
              UUID : a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 23
     
       Number   Major   Minor  RaidDevice State
          0       0        0       0      removed
          1       8       33       1      active sync   /dev/sdc1
    #拷贝内容
    [root@serv01 web]# cp /boot/* . -rvf
    [root@serv01 web]# mount
    /dev/sda2 on / type ext4 (rw)
    proc on /proc type proc (rw)
    sysfs on /sys type sysfs (rw)
    devpts on /dev/pts type devpts(rw,gid=5,mode=620)
    tmpfs on /dev/shm type tmpfs(rw,rootcontext="system_u:object_r:tmpfs_t:s0")
    /dev/sda1 on /boot type ext4 (rw)
    /dev/sda5 on /opt type ext4 (rw)
    /dev/md1 on /web type ext4 (rw)
    none on /proc/sys/fs/binfmt_misc type binfmt_misc(rw)
    /dev/sr0 on /iso type iso9660 (ro)
    [root@serv01 web]# df -h
    Filesystem            Size  Used Avail Use% Mounted on
    /dev/sda2             9.7G  1.1G 8.1G  12% /
    tmpfs                 188M     0 188M   0% /dev/shm
    /dev/sda1             194M   25M 160M  14% /boot
    /dev/sda5             4.0G  137M 3.7G   4% /opt
    /dev/md1              2.0G   54M 1.9G   3% /web
    /dev/sr0              3.4G  3.4G    0 100% /iso

### 第六步 添加磁盘 ###

#添加另一个磁盘
    [root@serv01 web]# fdisk /dev/sdd
    [root@serv01 web]# ls /dev/sdd
    sdd  sdd1 
    [root@serv01 web]# mdadm --manage /dev/md1--add /dev/sdd1
    mdadm: added /dev/sdd1
    [root@serv01 web]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2] sdc1[1]
         2095415 blocks super 1.2 [2/1] [_U]
         [=========>...........] recovery = 47.7% (1000064/2095415) finish=0.0min speed=250016K/sec
         
    unused devices: <none>
          
           [root@serv01web]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2] sdc1[1]
         2095415 blocks super 1.2 [2/2] [UU]
          
    unused devices: <none>
           [root@serv01web]# reboot
           [root@larrywenDesktop]# ssh 192.168.1.11
    root@192.168.1.11's password:
    Last login: Thu Aug  1 18:08:05 2013 from 192.168.1.1
    [root@serv01 ~]# cat /proc/mdstat
    Personalities : [raid1]
    md1 : active raid1 sdd1[2] sdc1[1]
         2095415 blocks super 1.2 [2/2] [UU]
         
    unused devices: <none>
    [root@serv01 ~]# df -h
    Filesystem            Size  Used Avail Use% Mounted on
    /dev/sda2             9.7G  1.1G 8.1G  12% /
    tmpfs                 188M     0 188M   0% /dev/shm
    /dev/sda1             194M   25M 160M  14% /boot
    /dev/sda5             4.0G  137M 3.7G   4% /opt
    /dev/md1              2.0G   54M 1.9G   3% /web
    /dev/sr0              3.4G  3.4G    0 100% /iso
     
    [root@serv01 ~]# mdadm --detail /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:18:482013
             State : clean
     Active Devices : 2
    Working Devices : 2
     Failed Devices : 0
     Spare Devices : 0
     
              Name : serv01.host.com:1  (localto host serv01.host.com)
              UUID :a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 60
     
       Number   Major   Minor  RaidDevice State
          2       8       49       0      active sync   /dev/sdd1
          1       8       33       1      active sync   /dev/sdc1
     
    #不重启添加磁盘
    #干掉/dev/sdc，o
    [root@serv01 ~]# fdisk /dev/sdc
    #查看详细信息，发现没坏
    [root@serv01 ~]# mdadm -D /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:24:242013
             State : clean
     Active Devices : 2
    Working Devices : 2
     Failed Devices : 0
     Spare Devices : 0
     
              Name : serv01.host.com:1  (localto host serv01.host.com)
              UUID : a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 60
     
       Number   Major   Minor  RaidDevice State
          2       8       49       0      active sync  /dev/sdd1
          1       8       33       1      active sync   /dev/sdc1
    #拷贝文件也不能看到
    [root@serv01 ~]# cp /etc/inittab /web
    #查看详细信息
    [root@serv01 ~]# mdadm -D /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:27:312013
              State : clean
     Active Devices : 2
    Working Devices : 2
     Failed Devices : 0
     Spare Devices : 0
     
              Name : serv01.host.com:1  (localto host serv01.host.com)
              UUID : a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 60
     
       Number   Major   Minor  RaidDevice State
          2       8       49       0      active sync   /dev/sdd1
          1       8       33       1      active sync   /dev/sdc1
     
    #标志/dev/sdc1错误
    root@serv01 ~]# mdadm --manage /dev/md1--fail /dev/sdc1
    mdadm: set /dev/sdc1 faulty in /dev/md1
    #查看状态
    [root@serv01 ~]# mdadm -D /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:28:312013
             State : clean, degraded
     Active Devices : 1
    Working Devices : 1
     Failed Devices : 1
     Spare Devices : 0
     
              Name : serv01.host.com:1  (localto host serv01.host.com)
              UUID : a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 61
     
       Number   Major   Minor  RaidDevice State
          2       8       49       0      active sync   /dev/sdd1
          1       0        0       1      removed
     
          1       8       33       -      faulty spare   /dev/sdc1
    [root@serv01 ~]# fdisk /dev/sde
    #添加/dev/sde1硬盘
    [root@serv01 ~]# mdadm --manage /dev/md1--add /dev/sde1
    mdadm: added /dev/sde1
    #查看详细信息
    [root@serv01 ~]# mdadm -D /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 3
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:29:562013
             State : clean, degraded, recovering
     Active Devices : 1
    Working Devices : 2
     Failed Devices : 1
     Spare Devices : 1
     
     Rebuild Status : 85% complete
     
              Name : serv01.host.com:1  (localto host serv01.host.com)
              UUID : a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 80
     
       Number   Major   Minor  RaidDevice State
          2       8       49       0      active sync   /dev/sdd1
          3       8       65       1      spare rebuilding   /dev/sde1
     
    1     8       33       -      faulty spare   /dev/sdc1
    #移除磁盘
    [root@serv01 ~]# mdadm --manage /dev/md1--remove /dev/sdc1
    mdadm: hot removed /dev/sdc1 from /dev/md1
    [root@serv01 ~]# mdadm -D /dev/md1
    /dev/md1:
           Version : 1.2
     Creation Time : Thu Aug  117:58:09 2013
        Raid Level : raid1
        Array Size : 2095415 (2046.65 MiB 2145.70 MB)
     Used Dev Size : 2095415 (2046.65 MiB 2145.70 MB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent
     
       Update Time : Thu Aug  1 18:30:092013
             State : clean
     Active Devices : 2
    Working Devices : 2
     Failed Devices : 0
     Spare Devices : 0
     
               Name : serv01.host.com:1  (local to host serv01.host.com)
              UUID : a8930aef:a5ddcdde:789a11bf:40f7eed6
            Events : 87
     
       Number   Major   Minor  RaidDevice State
          2       8       49       0      active sync   /dev/sdd1
          3       8       65       1      active sync   /dev/sde1

### 第七步 实验完毕，清空磁盘 ###

[root@serv01 ~]# umount /dev/md1
    #停掉
    [root@serv01 ~]# mdadm --manage /dev/md1--stop
    mdadm: stopped /dev/md1
    #删除配置文件
    [root@serv01 ~]# rm -rf /etc/mdadm.conf
    [root@serv01 ~]# fdisk -l |grep -e sdb -esdc -e sdd -e sde
    Disk /dev/sdf doesn't contain a validpartition table
    Disk /dev/sdg doesn't contain a validpartition table
    Disk /dev/sdb: 2147 MB, 2147483648 bytes
    Disk /dev/sdc: 2147 MB, 2147483648 bytes
    Disk /dev/sdd: 2147 MB, 2147483648 bytes
    Disk /dev/sde: 2147 MB, 2147483648 bytes
     
    #清除磁盘
    [root@serv01 ~]# mdadm --misc—zero-superblock /dev/sdb1
    [root@serv01 ~]# fdisk /dev/sdb
    #清除磁盘
    [root@serv01 ~]# mdadm --misc—zero-superblock /dev/sdc1
    [root@serv01 ~]# fdisk /dev/sdc

## 三 参考资料 ##

[http://zh.wikipedia.org/wiki/RAID][http_zh.wikipedia.org_wiki_RAID]

## 四 相关文章 ##

*  [磁盘管理——RAID 0][RAID 0]
 *  [磁盘管理——RAID 10][RAID 10]
 *  [磁盘管理——RAID 5][RAID 5]
 *  [磁盘管理——RAID 6][RAID 6]
 *  [磁盘管理——LVM][LVM]
 *  [磁盘管理——小实验][Link 1]

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[20130811085353140]: /images/20211104/0e70a700ebd8462c9ae56446014fd4d0.png
[20130811085401437]: /images/20211104/18fe5169f5ee49a6b0a2dcf13820ad60.png
[http_zh.wikipedia.org_wiki_RAID]: http://zh.wikipedia.org/wiki/RAID
[RAID 0]: http://blog.csdn.net/justdb/article/details/9874181
[RAID 10]: http://blog.csdn.net/justdb/article/details/10040697
[RAID 5]: http://blog.csdn.net/justdb/article/details/10041113
[RAID 6]: http://blog.csdn.net/justdb/article/details/10296089
[LVM]: http://blog.csdn.net/justdb/article/details/10296697
[Link 1]: http://blog.csdn.net/justdb/article/details/10297035