RAID:
Strong fault tolerance to ensure data security;
Better I/O transmission rate, effectively matching the speed of CPU and memory;
Large storage capacity ensures the storage of massive data;
Lower performance price ratio.
RAID 0
Strip mode
Data cutting, placing different disks in order
The free disk space is the number of disks * the minimum disk size
RAID 1
Mirror mode
Data replication
Disk free space is the number of disks * Minimum disk size / 2
RAID 5
Three or more disks form a disk array. Each time data is written, a disk is randomly selected for verification
The free disk space is: (number of disks - 1) * the minimum disk size
RAID 10(RAID 1 + RAID 0)
That is, a combination of RAID 0 and RAID 1
Disk free space is the number of disks * Minimum disk size / 2
1. Basic environment configuration
Prepare a virtual machine equipped with Centos7.2-1511 system and add four 20G hard disks.
(1) Configure the Yum source (I added the software package related to the mdadm tool in the Centos image)
① Remove the original networking source
mv /etc/yum.repos.d/* /media
② Write the local Yum source file local.repo
vi /etc/yum.repos.d/local.repo [centos] name=centos baseurl=file:///opt/centos enabled=1 gpgcheck=0
③ Mount image
mkdir /opt/centos mount CentOS-7-x86_64-DVD-1511.iso /opt/centos/ //Single mount mode is adopted here mount: /dev/loop0 is write-protected, mounting read-only
④ Turn off firewall and selinux
systemctl stop firewalld //The following all adopt single closing mode setenforce 0
⑤ Install mdadm tools using yum or up2date
yum instal -y mdadm
View current disk information
[root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 50G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 49.5G 0 part ├─centos-root 253:0 0 47.5G 0 lvm / └─centos-swap 253:1 0 2G 0 lvm [SWAP] sdb 8:16 0 20G 0 disk sdc 8:32 0 20G 0 disk sdd 8:48 0 20G 0 disk sde 8:64 0 20G 0 disk sr0 11:0 1 1024M 0 rom loop0 7:0 0 4G 0 loop /opt/centos
Create RAID 0 mode disk array (experiment with sdb and sdc disks this time)
[root@localhost ~]# mdadm -Cv /dev/md0 -l 0 -n 2 /dev/sd[b-c] mdadm: chunk size defaults to 512K mdadm: Defaulting to version 1.2 metadata mdadm: array /dev/md0 started.
md0: Created RAID Grade is RAID 0 of md0((device name) -C v: Create a device and display information. -l 0: RAID The level of is RAID 0. -n 2: establish RAID There are 2 pieces of equipment.
View RAID details
[root@localhost ~]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Wed Nov 24 09:09:35 2021
Raid Level : raid0
Array Size : 41910272 (39.97 GiB 42.92 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Wed Nov 24 09:09:35 2021
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Name : xnode1:0 (local to host xnode1)
UUID : a6c10beb:31a3423d:ad6c618a:adcd42dc
Events : 0
Number Major Minor RaidDevice State
0 8 16 0 active sync /dev/sdb
1 8 32 1 active sync /dev/sdc
Create and mount the file system for the created RAID
[root@localhost ~]# mkfs.xfs /dev/md0
meta-data=/dev/md0 isize=256 agcount=16, agsize=654720 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=10475520, imaxpct=25
= sunit=128 swidth=256 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=5120, version=2
= sectsz=512 sunit=8 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@localhost ~]# mkdir /raid0/
[root@localhost ~]# mount /dev/md0 /raid0/
[root@localhost ~]# df -Th /raid0/
Filesystem Type Size Used Avail Use% Mounted on
/dev/md0 xfs 40G 33M 40G 1% /raid0
Delete RAID operation
[root@localhost ~]# umount /raid0/ [root@localhost ~]# mdadm -S /dev/md0 mdadm: stopped /dev/md0 [root@localhost ~]# mdadm --zero-superblock /dev/sd[b-c] [root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 50G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 49.5G 0 part ├─centos-root 253:0 0 47.5G 0 lvm / └─centos-swap 253:1 0 2G 0 lvm [SWAP] sdb 8:16 0 20G 0 disk sdc 8:32 0 20G 0 disk sdd 8:48 0 20G 0 disk sde 8:64 0 20G 0 disk sr0 11:0 1 1024M 0 rom loop0 7:0 0 4G 0 loop /opt/centos [root@localhost ~]# rm -r /raid0/ rm: remove directory '/raid0/'? y
Simple raid 0 creation and deletion have been completed, as described above
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RAID 5 operation and maintenance operations are as follows
Simulate a RAID 5 disk array with four disks, one of which is a hot spare
[root@localhost ~]# mdadm -Cv /dev/md5 -l 5 -n 3 /dev/sd[b-d] --spare-devices=1 /dev/sde mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: chunk size defaults to 512K mdadm: size set to 20955136K mdadm: Defaulting to version 1.2 metadata mdadm: array /dev/md5 started.
View RAID details
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Wed Nov 24 09:35:24 2021
Raid Level : raid5
Array Size : 41910272 (39.97 GiB 42.92 GB)
Used Dev Size : 20955136 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Wed Nov 24 09:35:24 2021
State : clean, degraded, recovering
Active Devices : 2
Working Devices : 4
Failed Devices : 0
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Rebuild Status : 5% complete //Pay close attention to this prompt. At present, RAID5 disk array is still under construction. If the simulated hard disk is damaged, the whole RAID disk array will collapse. Enter the mdadm -D /dev/md5 command repeatedly to check the completion degree until 100%, and then you can carry out subsequent operations.
Name : localhost:5 (local to host localhost)
UUID : e15ef8c6:1eac185f:ce147026:ed3a88bd
Events : 1
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 spare rebuilding /dev/sdd
3 8 64 - spare /dev/sde
Analog hard disk failure
[root@localhost ~]# mdadm -f /dev/md5 /dev/sdb mdadm: set /dev/sdb faulty in /dev/md5
View the process of hot spare participating in raid reconstruction
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Wed Nov 24 09:35:24 2021
Raid Level : raid5
Array Size : 41910272 (39.97 GiB 42.92 GB)
Used Dev Size : 20955136 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Wed Nov 24 09:39:13 2021
State : clean, degraded, recovering
Active Devices : 2
Working Devices : 3
Failed Devices : 1
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Rebuild Status : 44% complete //Note here, ibid
Name : localhost:5 (local to host localhost)
UUID : e15ef8c6:1eac185f:ce147026:ed3a88bd
Events : 27
Number Major Minor RaidDevice State
3 8 64 0 spare rebuilding /dev/sde
1 8 32 1 active sync /dev/sdc
4 8 48 2 active sync /dev/sdd
0 8 16 - faulty /dev/sdb
Delete failed disk
[root@localhost ~]# mdadm -r /dev/md5 /dev/sdb mdadm: hot removed /dev/sdb from /dev/md5
View RAID details (failed disk removed)
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Wed Nov 24 09:35:24 2021
Raid Level : raid5
Array Size : 41910272 (39.97 GiB 42.92 GB)
Used Dev Size : 20955136 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Wed Nov 24 09:41:00 2021
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : localhost:5 (local to host localhost)
UUID : e15ef8c6:1eac185f:ce147026:ed3a88bd
Events : 38
Number Major Minor RaidDevice State
3 8 64 0 active sync /dev/sde
1 8 32 1 active sync /dev/sdc
4 8 48 2 active sync /dev/sdd
Create and mount the file system for the created RAID
[root@localhost ~]# mkfs.xfs /dev/md5
meta-data=/dev/md5 isize=256 agcount=16, agsize=654720 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=10475520, imaxpct=25
= sunit=128 swidth=256 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=5120, version=2
= sectsz=512 sunit=8 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@localhost ~]# mount /dev/md5 /mnt/
[root@localhost ~]# df -Th /mnt/
Filesystem Type Size Used Avail Use% Mounted on
/dev/md5 xfs 40G 33M 40G 1% /mnt
Delete RAID 5 and restore the clean state
[root@localhost ~]# umount /mnt/ [root@localhost ~]# mdadm -S /dev/md5 mdadm: stopped /dev/md5 [root@localhost ~]# mdadm --zero-superblock /dev/sd[c-e] [root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 50G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 49.5G 0 part ├─centos-root 253:0 0 47.5G 0 lvm / └─centos-swap 253:1 0 2G 0 lvm [SWAP] sdb 8:16 0 20G 0 disk sdc 8:32 0 20G 0 disk sdd 8:48 0 20G 0 disk sde 8:64 0 20G 0 disk sr0 11:0 1 1024M 0 rom loop0 7:0 0 4G 0 loop /opt/centos