1、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/sdemdadm: layout defaults to left-symmetricmdadm: layout defaults to left-symmetricmdadm: chunk size defaults to 512Kmdadm: size set to 20954624Kmdadm: Defaulting to version 1.2metadata mdadm: array /dev/md0 started.[root@linuxprobe ~]# mdadm -D /dev/md0/dev/md0:Version : 1.2Creation Time : Fri May 8 09:20:35 2017Raid Level : raid5Array Size : 41909248 (39.97 GiB 42.92 GB)Used Dev Size : 20954624 (19.98 GiB 21.46 GB)Raid Devices : 3Total Devices : 4Persistence : Superblock is persistentUpdate Time : Fri May 8 09:22:22 2017State : cleanActive Devices : 3Working Devices : 4Failed Devices : 0Spare Devices : 1Layout : left-symmetricChunk Size : 512KName : linuxprobe.com:0 (local to host linuxprobe.com)UUID : 44b1a152:3f1809d3:1d234916:4ac70481Events : 18Number Major Minor RaidDevice State0 8 16 0 active sync /dev/sdb1 8 32 1 active sync /dev/sdc4 8 48 2 active sync /dev/sdd3 8 64 - spare /dev/sde
2、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/md0mke2fs 1.42.9 (28-Dec-2013)Filesystem label=OS type: LinuxBlock size=4096 (log=2)Fragment size=4096 (log=2)Stride=128 blocks, Stripe width=256 blocks2621440 inodes, 10477312 blocks523865 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=2157969408320 block groups32768 blocks per group, 32768 fragments per group8192 inodes per groupSuperblock backups stored on blocks:32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,4096000, 7962624Allocating group tables: done Writing inode tables: doneCreating journal (32768 blocks): doneWriting 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
3、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，所以如果您的公司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/sdbmdadm: set /dev/sdb faulty in /dev/md0[root@linuxprobe ~]# mdadm -D /dev/md0/dev/md0:Version : 1.2Creation Time : Fri May 8 09:20:35 2017Raid Level : raid5Array 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 persistentUpdate Time : Fri May 8 09:23:51 2017State : active, degraded, recoveringActive Devices : 2Working Devices : 3Failed Devices : 1Spare Devices : 1Layout : left-symmetricChunk Size : 512KRebuild Status : 0% completeName : linuxprobe.com:0 (local to host linuxprobe.com)UUID : 44b1a152:3f1809d3:1d234916:4ac70481Events : 21Number Major Minor RaidDevice State3 8 64 0 spare rebuilding /dev/sde1 8 32 1 active sync /dev/sdc4 8 48 2 active sync /dev/sdd0 8 16 - faulty /dev/sdb
