磁盘阵列组+备份盘

咱们现在来创建一个RAID5磁盘阵列组+备份盘吧，-n 3参数代表创建这个RAID5所需的硬盘个数，-l 5参数代表RAID磁盘阵列的级别，而-x 1参数则代表有1块备份盘，当查看/dev/md0磁盘阵列组的时候就能看到有一块备份盘在等待中了。[root@linuxprobe ~]# 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 20954624K mdadm: Defaulting to version 1.2 metadata mdadm: array /dev/md0 started. [root@linuxprobe ~]# mdadm -D /dev/md0 /dev/md0: Version : 1.2 Creation Time : Fri May 8 09:20:35 2017 Raid Level : raid5 Array Size : 41909248 (39.97 GiB 42.92 GB) Used Dev Size : 20954624 (19.98 GiB 21.46 GB) Raid Devices : 3 Total Devices : 4 Persistence : Superblock is persistent Update Time : Fri May 8 09:22:22 2017 State : clean Active Devices : 3 Working Devices : 4 Failed Devices : 0 Spare Devices : 1 Layout : left-symmetric Chunk Size : 512K Name : linuxprobe.com:0 (local to host linuxprobe.com) UUID : 44b1a152:3f1809d3:1d234916:4ac70481 Events : 18Number Major Minor RaidDevice State 0 8 16 0 active sync /dev/sdb 1 8 32 1 active sync /dev/sdc 4 8 48 2 active sync /dev/sdd 3 8 64 - spare /dev/sde

把这块制作的RAID5磁盘阵列组格式化为ext4文件格式后挂载到目录上吧，这样就可以使用啦~[root@linuxprobe ~]# 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, 10477312 blocks 523865 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@linuxprobe ~]# echo '/dev/md0 /RAID ext4 defaults 0 0' >> /etc/fstab [root@linuxprobe ~]# mkdir /RAID [root@linuxprobe ~]# mount -a

最后就是见证奇迹的时刻啦，咱们再次把硬盘设备/dev/sdb移出磁盘阵列组，这样快速看下/dev/md0磁盘阵列组的状态就会发现备份盘已经被自动顶替上去，这是非常实用的，在RAID磁盘阵列组数据安全保证的基础上进一步提高数据可靠性，不差钱的话还是再买上一块备份盘以防万一吧。[root@linuxprobe ~]# mdadm /dev/md0 -f /dev/sdb mdadm: set /dev/sdb faulty in /dev/md0 [root@linuxprobe ~]# mdadm -D /dev/md0 /dev/md0: Version : 1.2 Creation Time : Fri May 8 09:20:35 2017 Raid Level : raid5 Array Size : 41909248 (39.97 GiB 42.92 GB) Used Dev Size : 20954624 (19.98 GiB 21.46 GB) Raid Devices : 3 Total Devices : 4 Persistence : Superblock is persistent Update Time : Fri May 8 09:23:51 2017 State : active, degraded, recovering Active Devices : 2 Working Devices : 3 Failed Devices : 1 Spare Devices : 1 Layout : left-symmetric Chunk Size : 512K Rebuild Status : 0% complete Name : linuxprobe.com:0 (local to host linuxprobe.com) UUID : 44b1a152:3f1809d3:1d234916:4ac70481 Events : 21Number 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