软件磁盘阵列

*由四个分区组成raid 5

*每个分区1G，每个分区最好一样大

*利用一个分区设为sparedisk

*sparedisk与其它raid分区一样大

*将此raid 5 设备挂载待/mnt/raid目录下

1.分区

[root@server3 mnt]# fdisk /dev/vdb

Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.

Be careful before using the write command.

Command (m for help): n

Partition type:

p primary (0 primary, 0 extended, 4 free)

e extended

Select (default p): p

Partition number (1-4, default 1):

First sector (2048-41943039, default 2048):

Using default value 2048

Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +1G

Partition 1 of type Linux and of size 1 GiB is set

Command (m for help): p

Disk /dev/vdb: 21.5 GB, 21474836480 bytes, 41943040 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0x7afa732b

Device Boot Start End Blocks Id System

/dev/vdb1 2048 2099199 1048576 83 Linux

/dev/vdb2 2099200 4196351 1048576 83 Linux

/dev/vdb3 4196352 6293503 1048576 83 Linux

/dev/vdb4 6293504 41943039 17824768 5 Extended

/dev/vdb5 6295552 8392703 1048576 83 Linux

/dev/vdb6 8394752 10491903 1048576 83 Linux

[root@server3 ~]# partprobe **可能会出现报错，重启就好

2.以mdadm创建RAID

[root@server3 ~]# mdadm --create --auto=yes /dev/md0 --level=5 --raid-devices=4 --spare-devices=1 /dev/vdb{2,3,5,6,7} <==个人问题，自己由新分了个区

mdadm: Defaulting to version 1.2 metadata

mdadm: array /dev/md0 started.

[root@server3 ~]# mdadm --detail /dev/md0

/dev/md0: <==RAID设备文件名

Version : 1.2

Creation Time : Mon Jan 21 15:41:42 2019 <==被创建时间

Raid Level : raid5 <==RAID等级

Array Size : 3142656 (3.00 GiB 3.22 GB) <==raid可用磁盘量

Used Dev Size : 1047552 (1023.00 MiB 1072.69 MB) <==每个设备的可用量

Raid Devices : 4 <==用作RAID的设备数量

Total Devices : 5 <==全部设备数量

Persistence : Superblock is persistent

Update Time : Mon Jan 21 15:41:52 2019

State : clean, degraded, recovering

Active Devices : 4 <==启动的设备数量

Working Devices : 5 <==可动作的设备数量

Failed Devices : 0 <==出现错误的设备数量

Spare Devices : 1 <==预备磁盘数量

Layout : left-symmetric

Chunk Size : 512K

Rebuild Status : 12% complete

Name : server3:0 (local to host server3)

UUID : 4c7f9840:5a192f12:004c417e:29d8c02e

Events : 2

Number Major Minor RaidDevice State

0 253 18 0 active sync /dev/vdb2

1 253 19 1 active sync /dev/vdb3

2 253 21 2 active sync /dev/vdb5

5 253 22 3 spare rebuilding /dev/vdb6

4 253 23 - spare /dev/vdb7

3.磁盘阵列的情况也可用下面这个文件查看

[root@server3 ~]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]

md0 : active raid5 vdb6[5] vdb7[4](S) vdb5[2] vdb3[1] vdb2[0]

3142656 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

格式化与挂载使用RAID

[root@server3 ~]# 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=384 blocks

196608 inodes, 785664 blocks

39283 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=805306368

24 block groups

32768 blocks per group, 32768 fragments per group

8192 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912

Allocating group tables: done

Writing inode tables: done

Creating journal (16384 blocks): done

Writing superblocks and filesystem accounting information: done

[root@server3 ~]# cd /mnt/

[root@server3 mnt]# ls raid/ <==自行创建

[root@server3 mnt]# mount /dev/md0 raid/

[root@server3 mnt]# df

Filesystem 1K-blocks Used Available Use% Mounted on

/dev/vda3 20243456 3441540 16801916 18% /

devtmpfs 493580 0 493580 0% /dev

tmpfs 508248 84 508164 1% /dev/shm

tmpfs 508248 13564 494684 3% /run

tmpfs 508248 0 508248 0% /sys/fs/cgroup

/dev/vda1 201380 133424 67956 67% /boot

tmpfs 101652 20 101632 1% /run/user/42

tmpfs 101652 0 101652 0% /run/user/0

/dev/md0 3027728 9216 2844996 1% /mnt/raid

4.错误救援模式

首先设置磁盘为错误

[root@server3 mnt]# cp -a /var/log raid/ *复制一些东西到/mnt/raid中去

[root@server3 mnt]# df /mnt/raid/ ; du -sm /mnt/raid/

Filesystem 1K-blocks Used Available Use% Mounted on

/dev/md0 3027728 15404 2838808 1% /mnt/raid

7 /mnt/raid/

假设/dev/vdb5出错了

[root@server3 mnt]# mdadm --manage /dev/md0 --fail /dev/vdb5

mdadm: set /dev/vdb5 faulty in /dev/md0

[root@server3 mnt]# mdadm --detail /dev/md0

/dev/md0:

Version : 1.2

Creation Time : Mon Jan 21 15:41:42 2019

Raid Level : raid5

Array Size : 3142656 (3.00 GiB 3.22 GB)

Used Dev Size : 1047552 (1023.00 MiB 1072.69 MB)

Raid Devices : 4

Total Devices : 5

Persistence : Superblock is persistent

Update Time : Mon Jan 21 16:18:46 2019

State : clean, degraded, recovering

Active Devices : 3

Working Devices : 4

Failed Devices : 1

Spare Devices : 1

Layout : left-symmetric

Chunk Size : 512K

Rebuild Status : 11% complete

Name : server3:0 (local to host server3)

UUID : 4c7f9840:5a192f12:004c417e:29d8c02e

Events : 21

Number Major Minor RaidDevice State

0 253 18 0 active sync /dev/vdb2

1 253 19 1 active sync /dev/vdb3

4 253 23 2 spare rebuilding /dev/vdb7

5 253 22 3 active sync /dev/vdb6

2 253 21 - faulty /dev/vdb5

[root@server3 mnt]# mdadm --manage /dev/md0 --fail /dev/vdb5

mdadm: set /dev/vdb5 faulty in /dev/md0

[root@server3 mnt]# mdadm --detail /dev/md0

/dev/md0:

Version : 1.2

Creation Time : Mon Jan 21 15:41:42 2019

Raid Level : raid5

Array Size : 3142656 (3.00 GiB 3.22 GB)

Used Dev Size : 1047552 (1023.00 MiB 1072.69 MB)

Raid Devices : 4

Total Devices : 5

Persistence : Superblock is persistent

Update Time : Mon Jan 21 16:18:46 2019

State : clean, degraded, recovering

Active Devices : 3

Working Devices : 4

Failed Devices : 1 **有一个出错了

Spare Devices : 1

Layout : left-symmetric

Chunk Size : 512K

Rebuild Status : 11% complete

Name : server3:0 (local to host server3)

UUID : 4c7f9840:5a192f12:004c417e:29d8c02e

Events : 21

Number Major Minor RaidDevice State

0 253 18 0 active sync /dev/vdb2

1 253 19 1 active sync /dev/vdb3

4 253 23 2 spare rebuilding /dev/vdb7

5 253 22 3 active sync /dev/vdb6

2 253 21 - faulty /dev/vdb5

5.将出错的磁盘删除并加入新磁盘

建立新的分区

[root@server3 mnt]# fdisk /dev/vdb

Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.

Be careful before using the write command.

Command (m for help): n

All primary partitions are in use

Adding logical partition 8

First sector (12593152-41943039, default 12593152):

Using default value 12593152

Last sector, +sectors or +size{K,M,G} (12593152-41943039, default 41943039): +1G

Partition 8 of type Linux and of size 1 GiB is set

Command (m for help): wq

The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table. The new table will be used at

the next reboot or after you run partprobe(8) or kpartx(8)

Syncing disks.

[root@server3 mnt]# partprobe

加入新的磁盘拔除由问题的磁盘

[root@server3 mnt]# mdadm --manage /dev/md0 --add /dev/vdb8 --remove /dev/vdb5

mdadm: added /dev/vdb8

mdadm: hot removed /dev/vdb5 from /dev/md0

[root@server3 mnt]# mdadm --detail /dev/md0

/dev/md0:

Version : 1.2

Creation Time : Mon Jan 21 15:41:42 2019

Raid Level : raid5

Array Size : 3142656 (3.00 GiB 3.22 GB)

Used Dev Size : 1047552 (1023.00 MiB 1072.69 MB)

Raid Devices : 4

Total Devices : 5

Persistence : Superblock is persistent

Update Time : Mon Jan 21 16:26:07 2019

State : clean

Active Devices : 4

Working Devices : 5

Failed Devices : 0

Spare Devices : 1

Layout : left-symmetric

Chunk Size : 512K

Name : server3:0 (local to host server3)

UUID : 4c7f9840:5a192f12:004c417e:29d8c02e

Events : 38

Number Major Minor RaidDevice State

0 253 18 0 active sync /dev/vdb2

1 253 19 1 active sync /dev/vdb3

4 253 23 2 active sync /dev/vdb7

5 253 22 3 active sync /dev/vdb6

6 253 24 - spare /dev/vdb8

6.开机自动启动raid并自动挂载

[root@server3 mnt]# vim /etc/fstab

/dev/md0 /mnt/raid ext4 defaults 1 2

[root@server3 mnt]# mount -a *检测一下是否有问题

7.关闭软件raid

[root@server3 mnt]# umount /dev/md0

[root@server3 mnt]# vim /etc/fstab *删除刚刚写入的那一行

[root@server3 mnt]# mdadm --stop /dev/md0

mdadm: stopped /dev/md0

unused devices: <none>

[root@server3 mnt]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]