Creation and example of RAID5 in raid

RAID
1) RAID supports dynamic capacity expansion

2)RAID支持磁盘加速3)RAID支持冗余

RAID 5: Requires more than three hard drives, disk capacity of multiple disks-1, to provide some disk speed and redundancy (fatal disadvantage: Generate checksum when the use of additional computing resources), allow damage to a hard disk

The command used to create the raid is mdadm, if not, install the mdadm package First

[[email protected]_01 ~]# mdadm -Cv /dev/md0 -a yes -n3 -l5 -x1 /dev/sd[c-f]  //创建raid5

Parameter explanation:

    --create               //表示要创建raid    --auto=yes /dev/md0    //是否自动检测,新建立的软件磁盘陈列设备为md0,md序号可以为0-9    --level=5               //磁盘阵列的等级，这里是raid5    -raid-devices           //所需使用的磁盘数量    --spare-devices          //添加作为预备（spare）磁盘的块数    /dev/sd[b-e]           //磁盘阵列所使用的设备，还可以写成“/dev/sdb /dev/sdc /dev/sdd /dev/sde”同样可以缩写为：mdadm –C –a yes /dev/md0 –l5 –n3 –x1 /dev/sd[b-e]    [[email protected]_01 ~]# mkfs.ext4 /dev/md0                      //将raid5格式化

    [[email protected]_01 ~]# mkdir /raid    [[email protected]_01 ~]# mount /dev/md0 /raid                    //创建并挂载           [[email protected]_01 ~]# df –Th                                 //查看挂载情况

    [[email protected]_01 ~]# mdadm --detail --scan>/etc/mdadm.conf  //全部追加到配置文件中    [[email protected]_01 ~]# vim /etc/mdadm.conf                     //编辑配置文件

    [[email protected]_01 ~]# vim /etc/fstab                            //编辑配置文件

    在里面加上一行     /dev/md0   /raid     ext4     defaults    0   0

Simulated disk corruption

[[email protected]_01 ~]# mdadm /dev/md0 -f /dev/sdd               //模拟磁盘损坏[[email protected]_01 ~]# cat /proc/mdstat                          //查看修复

RAID5 recovered.

[[email protected]_01 ~]# mdadm /dev/md0 -r /dev/sdd            //把坏的磁盘移除

Command parameters

-A  =  --assemble      激活-S  =  --stop           停止-D  =  --detail          查看raid详细信息-C  =  -- create         建立raid设备-v  =  --verbose        显示建立过程的详细信息-l  =  --level            raid的级别-n  =  --raid-devices    raid设备数-s  =  --scan            扫描raid设备-f  =  --fail              标示坏的硬盘-a  =  --add             添加硬盘-r  =  -remove           移除坏的硬盘

how to turn off RAID :

>>直接卸载/dev/md0,并且注释掉/etc/fstab文件中的配置umount  /dev/md0                  //解除挂接vi  /etc/fstab                      //将fstab里面的开机自动挂载注释掉#/dev/md0     /var/www/html     ext4     defaults         0   0mdadm --stop /dev/md0           //停止md0磁盘服务

Two ways to see if a raid was created successfully

cat  /proc/mdstatmdadm  --detail  /dev/md

Creation and example of RAID5 in raid