[ root@centos68 ~]# fdisk /dev/sdb
Command(m for help): p
Disk /dev/sdb:53.7 GB,53687091200 bytes
255 heads,63 sectors/track,6527 cylinders
Units = cylinders of16065*512=8225280 bytes
Sector size(logical/physical):512 bytes /512 bytes
I/O size(minimum/optimal):512 bytes /512 bytes
Disk identifier:0xb5c926a7
Device Boot Start End Blocks Id System
/dev/sdb1 13917314632715 Extended
/dev/sdb5 1654525319283 Linux
/dev/sdb6 65513085253223+83 Linux
/dev/sdb7 130919625253223+83 Linux
Command(m for help): t
Partition number(1-7):5
Hex code(type L to list codes): fd
Changed system type of partition 5 to fd(Linux raid autodetect)Command(m for help): t
Partition number(1-7):6
Hex code(type L to list codes): fd
Changed system type of partition 6 to fd(Linux raid autodetect)Command(m for help): t
Partition number(1-7):7
Hex code(type L to list codes): fd
Changed system type of partition 7 to fd(Linux raid autodetect)Command(m for help): p
Disk /dev/sdb:53.7 GB,53687091200 bytes
255 heads,63 sectors/track,6527 cylinders
Units = cylinders of16065*512=8225280 bytes
Sector size(logical/physical):512 bytes /512 bytes
I/O size(minimum/optimal):512 bytes /512 bytes
Disk identifier:0xb5c926a7
Device Boot Start End Blocks Id System
/dev/sdb1 13917314632715 Extended
/dev/sdb5 16545253192 fd Linux raid autodetect
/dev/sdb6 65513085253223+ fd Linux raid autodetect
/dev/sdb7 130919625253223+ fd Linux raid autodetect
Save and exit
Command(m for help): w
The partition table has been altered!
Force to reread the disk partition table (run several times)
[ root@centos68 ~]# partx -a /dev/sdb
[ root@centos68 ~]# fdisk /dev/sdb
Command(m for help): n
Command action
l logical(5 or over)
p primary partition(1-4)
l
First cylinder(1963-3917,default1963):
Using default value 1963
Last cylinder,+cylinders or +size{K,M,G}(1963-3917,default3917):+5G
Command(m for help): t
Partition number(1-8):8
Hex code(type L to list codes): fd
Changed system type of partition 8 to fd(Linux raid autodetect)Command(m for help): p
Disk /dev/sdb:53.7 GB,53687091200 bytes
255 heads,63 sectors/track,6527 cylinders
Units = cylinders of16065*512=8225280 bytes
Sector size(logical/physical):512 bytes /512 bytes
I/O size(minimum/optimal):512 bytes /512 bytes
Disk identifier:0xb5c926a7
Device Boot Start End Blocks Id System
/dev/sdb1 13917314632715 Extended
/dev/sdb5 16545253192 fd Linux raid autodetect
/dev/sdb6 65513085253223+ fd Linux raid autodetect
/dev/sdb7 130919625253223+ fd Linux raid autodetect
/dev/sdb8 196326165253223+ fd Linux raid autodetect
Command(m for help): w
The partition table has been altered!
# Force reread partition table
[ root@centos68 ~]# partx -a /dev/sdb
[ root@centos68 ~]# mdadm -C /dev/md0 -a yes -n 3-x 1-l 5/dev/sdb{5,6,7,8}
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
View the data synchronization process
[ root@centos68 ~]# watch -n1 'cat /proc/mdstat'
View the status of all md type devices
[ root@centos68 ~]# cat /proc/mdstat
Personalities :[raid6][raid5][raid4]
md0 : active raid5 sdb7[4] sdb8[3](S) sdb6[1] sdb5[0]10498048 blocks super1.2 level 5, 512k chunk, algorithm 2[3/3][UUU]
unused devices:<none>
View RAID details
[ root@centos68 ~]# mdadm -D /dev/md0
/dev/md0:
Version :1.2
Creation Time : Thu Jun 2503:49:102020
Raid Level : raid5
Array Size :10498048(10.01 GiB 10.75 GB)
Used Dev Size :5249024(5.01 GiB 5.38 GB)
Raid Devices :3
Total Devices :4
Persistence : Superblock is persistent
Update Time : Thu Jun 2503:53:072020
State : clean
Active Devices :3
Working Devices :4
Failed Devices :0
Spare Devices :1
Layout : left-symmetric
Chunk Size : 512K
Name : centos68:0(local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events :18
Number Major Minor RaidDevice State
08210 active sync /dev/sdb5
18221 active sync /dev/sdb6
48232 active sync /dev/sdb7
3824- spare /dev/sdb8
[ root@centos68 ~]# mke2fs -t ext4 /dev/md0
View
[ root@centos68 ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_centos68-lv_root
50 G 861M 46G 2%/
tmpfs 931M 0 931M 0%/dev/shm
/dev/sda1 477M 39M 413M 9%/boot
/dev/mapper/vg_centos68-lv_home
45 G 52M 43G 1%/home
/dev/md0 9.8G 23M 9.3G 1%/data
Achieve automatic mounting at boot
[ root@centos68 ~]# blkid /dev/md0
/dev/md0: UUID="e2303c17-62a6-4938-aa7a-d5b9c52ab4ea" TYPE="ext4"
# It is recommended to use UUID for mounting or LABEL volume label mounting
[ root@centos68 ~]# tail -1/etc/fstab
UUID=e2303c17-62a6-4938-aa7a-d5b9c52ab4ea /data defaults,acl 00
[ root@centos68 ~]# mdadm /dev/md0 -f /dev/sdb5
mdadm:set/dev/sdb5 faulty in/dev/md0
View the synchronization process of the spare disk
[ root@centos68 ~]# cat /proc/mdstat #Or use watch-n1 'cat /proc/mdstat'Observe the recovery process dynamically
Personalities :[raid6][raid5][raid4]
md0 : active raid5 sdb7[4] sdb8[3] sdb6[1] sdb5[0](F)10498048 blocks super1.2 level 5, 512k chunk, algorithm 2[3/2][_UU][=>...................] recovery =6.8%(359808/5249024) finish=0.6min speed=119936K/sec
unused devices:<none>
View RAID details again
== The spare disk sdb8 has replaced the bad disk sdb5==
[ root@centos68 ~]# mdadm -D /dev/md0
/dev/md0:
Version :1.2
Creation Time : Thu Jun 2503:49:102020
Raid Level : raid5
Array Size :10498048(10.01 GiB 10.75 GB)
Used Dev Size :5249024(5.01 GiB 5.38 GB)
Raid Devices :3
Total Devices :4
Persistence : Superblock is persistent
Update Time : Thu Jun 2504:07:212020
State : clean
Active Devices :3
Working Devices :3
Failed Devices :1
Spare Devices :0
Layout : left-symmetric
Chunk Size : 512K
Name : centos68:0(local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events :37
Number Major Minor RaidDevice State
38240 active sync /dev/sdb8
18221 active sync /dev/sdb6
48232 active sync /dev/sdb7
0821- faulty /dev/sdb5
Copy test data to RAID-5 mount point /data
[ root@centos68 ~]# cp /etc/passwd /data/[root@centos68 ~]# ll /data/passwd
- rw-r--r--.1 root root 887 Jun 2504:13/data/passwd
[ root@centos68 ~]# cat /etc/passwd
Simulate bad disk /dev/sdb8, observe the state state
[ root@centos68 ~]# mdadm /dev/md0 -f /dev/sdb8
mdadm:set/dev/sdb8 faulty in/dev/md0
[ root@centos68 ~]# mdadm -D /dev/md0
/dev/md0:
Version :1.2
Creation Time : Thu Jun 2503:49:102020
Raid Level : raid5
Array Size :10498048(10.01 GiB 10.75 GB)
Used Dev Size :5249024(5.01 GiB 5.38 GB)
Raid Devices :3
Total Devices :4
Persistence : Superblock is persistent
Update Time : Thu Jun 2504:15:232020
State : clean, degraded #Degraded operating mode
Active Devices :2
Working Devices :2
Failed Devices :2
Spare Devices :0
Layout : left-symmetric #The default layout is left symmetrical
Chunk Size : 512K
Name : centos68:0(local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events :39
Number Major Minor RaidDevice State
0000 removed
18221 active sync /dev/sdb6
48232 active sync /dev/sdb7
0821- faulty /dev/sdb5
3824- faulty /dev/sdb8
Test whether the data is normally accessed
[ root@centos68 ~]# cd /data
[ root@centos68 data]# cat passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
[ root@centos68 data]# mdadm /dev/md0 -r /dev/sdb5
mdadm: hot removed /dev/sdb5 from/dev/md0
[ root@centos68 data]# mdadm /dev/md0 -r /dev/sdb8
mdadm: hot removed /dev/sdb8 from/dev/md0
[ root@centos68 data]# mdadm -D /dev/md0
/dev/md0:
Version :1.2
Creation Time : Thu Jun 2503:49:102020
Raid Level : raid5
Array Size :10498048(10.01 GiB 10.75 GB)
Used Dev Size :5249024(5.01 GiB 5.38 GB)
Raid Devices :3
Total Devices :2
Persistence : Superblock is persistent
Update Time : Thu Jun 2504:19:052020
State : clean, degraded
Active Devices :2
Working Devices :2
Failed Devices :0
Spare Devices :0
Layout : left-symmetric
Chunk Size : 512K
Name : centos68:0(local to host centos68)
UUID : be5cb284:275497f7:be5982ec:ce03ed15
Events :45
Number Major Minor RaidDevice State
0000 removed
18221 active sync /dev/sdb6
48232 active sync /dev/sdb7
[ root@centos68 data]# mdadm /dev/md0 -a /dev/sdb5
mdadm: added /dev/sdb5
View the data synchronization process
[ root@centos68 data]# watch -n1 'cat /proc/mdstat'
Every 1.0s: cat /proc/mdstat Thu Jun 2504:23:042020
Personalities :[raid6][raid5][raid4]
md0 : active raid5 sdb5[3] sdb7[4] sdb6[1]10498048 blocks super1.2 level 5, 512k chunk, algorithm 2[3/2][_UU][================>....] recovery =82.0%(4309708/5249024) finish=0.1min speed=1
00386 K/sec
unused devices:<none>
Reference document: https://cloud.tencent.com/developer/article/1562726
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