Server Disk RAID Configuration

 Unlike general PCs, servers and storage use a technology called RAID (Redundant Array of Independent Disks) to ensure disk stability, consistency, and data preservation.

The speed and stability vary depending on the configuration of RAID0, 1, 2, 3, 4, 5, 10, etc. by combining multiple disks.

To configure RAID on a server, you need a RAID Controller device, and the more expensive the product, the more RAID configurations you can have.

I would like to explain the most commonly used combinations, RAID 0, 1, 5, and 6.


RAID0 - The fastest but least stable method. As shown in the figure, assuming that 1,2,3,4 are one data, the data is arranged in a stripe shape on two disks, so it is fast to read or write data, but if one disk fails, the data will be broken. In other words, it can be said that there is no stability at all.

Availability: 500GB * 2ea = 1TB

RAID1 - The speed is the same as a general single disk, but since the same data is stored on two disks, the data is still alive even if one disk fails. As shown in the figure, it is a technology that stores the same data on disks, and is usually used in the OS area of ​​a server for data stability.

Availability: 500GB * 2ea = 500GB

RAID5 - When compared to a general single disk, the reading speed is fast, but the writing speed is slow. However, it has a certain level of stability, so even if one disk is lost, as shown in the figure above, the data on 1, 2, and 3 is still alive, so there is no data damage. It is usually used in the DATA area of ​​a server and the storage configuration. Availability: 500GB * 3ea = 1TB (n-1)

RAID6 - RAID configuration that emphasizes stability, although the speed is slow. As shown in the picture above, even if 2 disks are removed, data on 1, 2, 3, and 4 are still alive, so there is no data loss. However, the disadvantage is that the construction cost is high and an expensive RAID controller device must be used.
Availability: 500GB * 4ea = 1TB (n-2)

For a detailed speed comparison by RAID, please refer to Namu Wiki with the picture below.

Source : https://namu.wiki/w/RAID

And Global Hot Spare is commonly used in storage, and it also has a function that acts as a substitute when a problem occurs while using RAID grouping.

Of course, it can also be used as a RAID5 + Global Hot Spare configuration even if it is not grouped.

However, Global Hot Spare is a disk that cannot be used unless there is a failure, so it can be seen as a backup device that is not in operation.


Storage uses multiple disks, and for stability, RAID grouping + Hot Spare is often used as above.

Availability: 500GB * 11ea (configuration as shown) = 3TB
※ 1TB availability per group, Spare Disk is not used, but there is no data loss even if up to 5 disks fail

RAID configuration can be configured to suit each company's internal financial situation, environment, etc.

When I configure a server, I usually configure the server disk configuration as OS area (RAID1) + DATA area (RAID5).

For example, I purchase 5 500GB disks for a server, group 2 as RAID1 and use them as C Drive (500GB usable), and group 3 as RAID5 and use them as D Drive (1TB usable).

If you have a little more money, I think you can complete a highly stable server by adding 1 Global Hot Spare.

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