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It depends on utility called mdadm
(multiple disk administration)
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I can use more than one hard disk and manage them as a
compact unit called RAID device.
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Go to VM tabe, add hard disks of the same size, and it
should be the same size. Then reboot.
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So we will have three hard disks sdb, sdc, sdd
Configuration
Steps:
1-
fdisk –l
//it will show all
hard disks with their already
//created partitions.
2-
fdisk –cu /dev/sdb
//c: makes sure that
the partition label is mbr
//u:disk spaces
counter by sectors.
m:help
n:new partition
p:primary
1:partition number
fisrt sector: default
last sector:default
t: system id=fd(Liunex raid autodetect)
//repeat
this for the two other hard disks with the same conf.
*mark: if the disk size it by TB, you
should change the partition’s label type to GPT( parted, mklabel gpt)
*all partitions should have the same
size.
*partition type should be RAID
3-
partprobe /dev/sdb1
partprobe /dev/sdc1
partprobe /dev/sdd1
// informs os about
partition table changes on disk
//use partition
without reboot
4-
man mdadm (manage MD devices) also known as
linux sw RAID
5-
mdadm --create /dev/md0 --level=5 –raid-devices=3 /dev/sdb
/dev/sdc /dev/sdd
6-
mdadm --detail /dev/md0
7-
watch cat /proc/mdstat
//shows RAID
statistics
8-
mkfs.ext4 /dev/md0
//make file system to
raid, now you are dealing with partitions through the md0 layer.
9-
mkdir /myriad
10-
mount /dev/md0 /my raid
11-
vi /etc/fstab
/dev/md0
/myraid /ext4 defaults
0 0
12-
mount –a
13-
cp –r /etc/ /myraid/
cp –r /usr/ /myraid/
//we will try to write
data on the array disk
*mark: at raid 5 at
least one hard disk that can be faulty.
14-
mdadm /dev/md0 –f /dev/sdc1
//we will fail a hard
disk sdc
15-
cat /proc/mdstat
// sdc1 will be faulty
and down
*try to write data it will be written
normally
16-
df –h
17-
mdadm /dev/md0 –r /dev/sdc1
//hot remove
18-
mdadm /dev/md0 –a /dev/sde1
//add new device to
array
Normally Linux system doesn’t automatically remember
components that are part of RAID. This info should be added to /etc/mdadm.conf.
19-
mdadm --detail --scan
mdadm --detail /dev/md0
20-
mdadm --detail --scan > /etc/mdadm.conf
//append the conf. file
