linux下磁盘阵列配置方法
一、准备好4块磁盘，如：/dev/sdb、/dev/sdc、/dev/sdd、/dev/sde
1、创建 raid5
[root@docker ~]# mdadm --create /dev/md0 --level=5 --raid-devices=3 --spare-devices=1 /dev/sd[b-e]
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
设定/dev/sde为备用设备，其余为活动设备，备用设备的作用是一旦某一设备损坏可立即使用备用设备替换2、查看 详情
[root@docker ~]# mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Nov 21 14:20:48 2015
Raid Level : raid5
Array Size : 104792064 (99.94 GiB 107.31 GB)
Used Dev Size : 52396032 (49.97 GiB 53.65 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sat Nov 21 14:25:21 2015
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Name : docker.example.com:0 (local to host docker.example.com)
UUID : ac110faf:5f345efc:8540013c:cd7f95bc
Events : 46
Number 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/sde3、格式化阵列
[root@docker ~]# mkfs.ext4 /dev/md0
mke2fs 1.41.12 (17-May-2010)
文件系统标签=
操作系统:Linux
块大小=4096 (log=2)
分块大小=4096 (log=2)
Stride=128 blocks, Stripe width=256 blocks
6553600 inodes, 26198016 blocks
1309900 blocks (5.00%) reserved for the super user
第一个数据块=0
Maximum filesystem blocks=4294967296
800 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, 11239424, 20480000, 23887872
正在写入inode表: 完成
Creating journal (32768 blocks): 完成
Writing superblocks and filesystem accounting information: 完成
This filesystem will be automatically checked every 28 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.4、挂载 raid5
[root@docker ~]# mount /dev/md0 /mnt
[root@docker ~]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda1 ext4 98G 4.2G 89G 5% /
tmpfs tmpfs 99M 1.5M 98M 2% /run
/dev/md0 ext4 107G 218M 106G 1% /mnt二、模拟磁盘故障
1、将/dev/sdc标记为出现故障的磁盘
[root@docker ~]# mdadm /dev/md0 --fail /dev/sdc
mdadm: set /dev/sdc faulty in /dev/md0
[root@docker ~]# mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Nov 21 14:20:48 2015
Raid Level : raid5
Array Size : 104792064 (99.94 GiB 107.31 GB)
Used Dev Size : 52396032 (49.97 GiB 53.65 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sat Nov 21 14:40:45 2015
State : clean, degraded, recovering
Active Devices : 2
Working Devices : 3
Failed Devices : 1
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Rebuild Status : 20% complete
Name : docker.example.com:0 (local to host docker.example.com)
UUID : ac110faf:5f345efc:8540013c:cd7f95bc
Events : 51
Number Major Minor RaidDevice State
0 8 16 0 active sync /dev/sdb
3 8 64 1 spare rebuilding /dev/sde
4 8 48 2 active sync /dev/sdd
1 8 32 - faulty /dev/sdc
[root@docker ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdd[4] sde[3] sdc[1](F) sdb[0]
104792064 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [U_U]
[==============>......] recovery = 72.4% (37981412/52396032) finish=1.2min speed=189532K/sec
unused devices: <none>
注意：以上信息表明阵列正在重建，当设备出现故障或被标记故障时，相应设备的方括号后将被标以(F)2、重建完数据后，再次查看阵列状态时，就会发现当前的RAID设备又恢复了正常
[root@docker ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdd[4] sde[3] sdc[1](F) sdb[0]
104792064 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>3、移除故障磁盘
[root@docker ~]# mdadm /dev/md0 --remove /dev/sdc
mdadm: hot removed /dev/sdc from /dev/md0
[root@docker ~]# mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Nov 21 14:20:48 2015
Raid Level : raid5
Array Size : 104792064 (99.94 GiB 107.31 GB)
Used Dev Size : 52396032 (49.97 GiB 53.65 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Sat Nov 21 14:46:33 2015
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : docker.example.com:0 (local to host docker.example.com)
UUID : ac110faf:5f345efc:8540013c:cd7f95bc
Events : 68
Number Major Minor RaidDevice State
0 8 16 0 active sync /dev/sdb
3 8 64 1 active sync /dev/sde
4 8 48 2 active sync /dev/sdd
注意：此时发现没有备用磁盘 4、添加备用磁盘
[root@docker ~]# mdadm /dev/md0 --add /dev/sdc
mdadm: added /dev/sdc
[root@docker ~]# mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Nov 21 14:20:48 2015
Raid Level : raid5
Array Size : 104792064 (99.94 GiB 107.31 GB)
Used Dev Size : 52396032 (49.97 GiB 53.65 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sat Nov 21 14:48:11 2015
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Name : docker.example.com:0 (local to host docker.example.com)
UUID : ac110faf:5f345efc:8540013c:cd7f95bc
Events : 69
Number Major Minor RaidDevice State
0 8 16 0 active sync /dev/sdb
3 8 64 1 active sync /dev/sde
4 8 48 2 active sync /dev/sdd
5 8 32 - spare /dev/sdc