With RAID technology, we can combine multiple disks in some way to improve performance or reliability.

Frequently Used Levels

  • RAID0
  • RAID1
  • RAID5
  • RAID10
  • RAID50
  • JBOD

RAID 0

Here are some common features of RAID 0:

Feature Description
Read write performance Upgraded
Available spaces N * min(S1, S2, …)
Fault tolerance None
Minimum disk numbers 2 or more disks
  • N = Number of disks.
  • min() = The minimal space disk between disks.
  • S{1|2|N} = Disks.
img

Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509075

RAID 1

Here are some common features of RAID 1:

Feature Description
Read performance Upgraded
Write performance Degraded
Available spaces 1 * min(S1, S2, …)
Fault tolerance N - 1 disk.
Minimum disk numbers 2 or more disks
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Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509082

RAID 2 (OBSOLETE)

RAID 2 is deprecated.

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Image created by knakts. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10648378

RAID 3 (OBSOLETE)

RAID 3 is replaced by RAID 5.

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Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509118

RAID 4

Multiple diskettes of exclusive or calculated values are stored on a checkout disk, any of which can be used to calculate the damaged disk’s data by using another disk when it is damaged, but if the checksum disk is also broken, then the data isn’t able to be recovered. Therefore, the reliability of this combination is very low.

Here are some common features of RAID 4:

Feature Description
Read performance Upgraded
Write performance Degraded
Available spaces (N - 1) * min(S1, S2, …)
Fault tolerance One disk.
Minimum disk numbers 3 or more disks
img

Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509154

RAID 5

Here are some common features of RAID 5:

Feature Description
Read write performance Upgraded
Available spaces (N - 1) * min(S1, S2, …)
Fault tolerance One disk.
Minimum disk numbers 3 or more disks
img

Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509158

RAID 6

Here are some common features of RAID 6:

Feature Description
Read write performance Upgraded
Available spaces (N - 2) * min(S1, S2, …)
Fault tolerance Two disks.
Minimum disk numbers 4 or more disks
img

Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509166

Nested RAID

RAID 10

Here are some common features of RAID 10:

Feature Description
Read write performance Upgraded
Available spaces N * min(S1, S2, …) / 2
Fault tolerance One faulty disk at most in every image.
Minimum disk numbers 4 or more disks
img

Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22591138

RAID 50

Here are some common features of RAID 50:

Feature Description
Read write performance Upgraded
Available spaces N * min(S1, S2, …) / 3
Fault tolerance One faulty disk at most in every image.
Minimum disk numbers 6 or more disks
img

Image created by Kauberry. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6895750

RAID 60

Here are some common features of RAID 60:

Feature Description
Read write performance Upgraded
Available spaces N * min(S1, S2, …) / 4
Fault tolerance One faulty disk at most in every image.
Minimum disk numbers 8 or more disks
img

Image created by Rusl. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30106105

Non-RAID drive architectures

JBOD

One of the Non-RAID drive architectures. The space of multiple disks is combined into a large continuous space.

Here are some common features of JBOD:

Feature Description
Read write performance Unknown
Available spaces sum(S1, S2, …)
Fault tolerance None
Minimum disk numbers 2 or more disks
  • sum() = The summation of all disk spaces.
img

Image created by Cburnett. CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1509098

Manage Linux Software RAID

The used partitions’ systems should be set to Linux raid autodetect.

Linux supports LINEAR md devices:

  • RAID0 (striping)
  • RAID1 (mirroring)
  • RAID4
  • RAID5
  • RAID6
  • RAID10
  • MULTIPATH
  • FAULTY
  • CONTAINER.

Here are some mode specific options for mdadm command:

Option Description
-A Assemble a pre-existing array.
-C Create a new array, -n #: Specify the number of active devices in the array. -l #: Set RAID level. When used with –create, options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container.
-F Select monitor mode.

Here are some manage mode options for mdadm command:

Option Description
-a Hot-add listed devices.
-r Remove listed devices.
-f Mark listed devices as faulty.

Here are some misc mode options for mdadm command:

Option Description
-D Print details of one or more md devices.
-S Deactivate aray, releasing all resources. 
1

mdadm [MODE] <raiddevice> [OPTION] <component-devices>

View md status

1

cat /proc/mdstat

References Standard RAID levels, Nested RAID levels, Non-RAID drive architectures, MDADM(8)

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