RAID6 AND ITS COFIGURTION

In this tutorial we are going to learn about Raid6 and how to configure.
Raid6 also known as double parity.It requires four disk so if two disk crashes can take data from two disk. Fault tolerance is low as compared to raid 5.
Drawback- Data transactions are slowed down due to the parity rebuilding an array in which one drive failed can take a long time so its a complex technology.

RAID6
Now how to configure it-
1. Create four partitions.
2. Change its type to Raid linux:

[root@localhost ~]# fdisk /dev/sda
The number of cylinders for this disk is set to 2640.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): t
Partition number (1-8): 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 (1-8): 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 (1-8): 7
Hex code (type L to list codes): fd
Changed system type of partition 7 to fd (Linux raid autodetect)

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/sda: 21.7 GB, 21719023616 bytes
255 heads, 63 sectors/track, 2640 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        1912    15358108+  83  Linux
/dev/sda2            1913        2167     2048287+  82  Linux swap / Solaris
/dev/sda4            2168        2640     3799372+   5  Extended
/dev/sda5            2168        2229      497983+  fd  Linux raid autodetect
/dev/sda6            2230        2291      497983+  fd  Linux raid autodetect
/dev/sda7            2292        2353      497983+  fd  Linux raid autodetect
/dev/sda8            2354        2415      497983+  fd  Linux raid autodetect
Command (m for help): w
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.
Syncing disks.

[root@localhost ~]# partprobe /dev/sda
 3. After making partition raid we are going to create raid6
[root@localhost ~]# mdadm --create /dev/md6 --level=6 --raid-devices=4 /dev/sda5 /dev/sda6 /dev/sda7 /dev/sda8

mdadm: array /dev/md6 started.

In this entry – -level what type of raid we want it to be ,- -raid-devices means how many devices you want to connect.

Your raid 6 is ready you can can check it by typing

[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md6 : active raid6 sda8[3] sda7[2] sda6[1] sda5[0]
      995712 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU]
unused devices: 

RAID1 AND ITS CONFIGURATION

Raid0 AND ITS CONFIGURATION

RAID5 AND ITS CONFIGURATION

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