RAID VS AHCI: Which Is Better? [Complete Guide]

RAID vs. AHCI, Which One Should I Choose?

"Two days ago, when I installed Windows 10 for the mechanical hard drive, I accidentally set the SATA operation mode to RAID. I felt that the boot speed was much slower than before. Compared with AHCI mode, will the performance of mechanical hard drives be affected in RAID mode? Can someone tell me which is better, RAID or AHCI?”

Since RAID allows you to create a bootable RAID volume, when your motherboard is set to RAID and booted, it will temporarily transfer control to the RAID BIOS. And it will find a bootable RAID volume, which may increase a few Start time in seconds, but it does not affect performance.

If you want to know which is better, RAID or AHCI, you need to understand the essential difference between the two.

What is RAID?

Redundant Array of Independent Disks, or RAID for short, was also called Redundant Array of Inexpensive Disks before. RAID is essentially is a data storage virtualization technology that combines multiple physical disk drive components into one or more logical units (arrays). It has the advantages of fast transmission rate, high security, and data protection, and is more suitable for mechanical hard drives than solid state drives.

RAID can also be used as a SATA control mode, and can be divided into Software RAID control mode and Hardware RAID control mode. The RAID levels supported by these two types of RAID control modes are also different. Under normal circumstances, Hardware RAID is more powerful than Software RAID, which is especially obvious in high-level RAID. So what are the levels of RAID? I will give you a detailed introduction next.

Differences in RAID Levels

Data is distributed on hard disks in a variety of ways, and RAID can be divided into multiple levels according to data redundancy and performance. Common levels are RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, etc. They all use a "parity check" protection scheme, which can provide a fault-tolerant mechanism for a given data set. In addition, the differences between these levels are not only reflected in their respective advantages and disadvantages, but also mean differences in working methods. You need to choose according to your own situation. Below I will introduce the common RAID levels to all of you.

RAID 0

This level allows you to write data to multiple hard drives. And multiple hard drives process the data together, which is also called "disk striping". In addition, RAID 0 also allows you to use a combination of software and hardware for configuration, which can support most controllers.

• Main Advantage: It can effectively improve server performance and has better compatibility.
• Main Disadvantage: This level does not have fault tolerance. When one of the hard disks fails, the entire strip will be affected, resulting in the loss of all hard disk data. Therefore, it is recommended that you make a backup in advance.

RAID 1

In the same RAID array, each hard disk can be used as a copy. When any one of the hard disks fails, the data will be copied directly to the other hard disk. Therefore, this configuration is also called "disk mirroring".

• Main Advantage: Compared with RAID 0, this level of fault tolerance is higher and can better protect your data security.
• Main Disadvantage: Since RAID 1 allows data to be stored across multiple hard drives, the writing speed is relatively slow and overall performance is insufficient. In addition, due to data redundancy, the total usable capacity of the array in this configuration is relatively small, only about 50% of the total capacity of the hard disk.

RAID 5

This level is essentially an improvement of RAID 1, consisting of block-level striping with distributed parity, and is mainly used for enterprise NAS devices and business servers.

• Main Advantage: It reduces the performance loss caused by RAID 1, and retains a high fault tolerance rate, reaching a relatively balanced state, suitable for professional data storage. In addition, RAID 5 also supports the server hard disk "hot swap" function, allowing you to swap hard disks into the array during system startup and operation.
• Main Disadvantage: If you are using a large server, when multiple users access an array and write data at the same time, the write performance will be insufficient.

RAID 6

This level is basically the same as RAID 5, the only difference is: RAID 6 uses two independent "parity check" protection schemes, consisting of block-level striping with dual distributed parity. The number of simultaneous hard disk failures can be controlled within two, so that data is not affected.

RAID 10

This level is essentially a hybrid RAID combination, which mainly implements stripe set mirroring through parity, and can also be seen as a combination of RAID 1 and RAID 0 (ie, RAID 1+0). Among them, RAID 1 is a redundant backup array with high security; RAID 0 is a read-write array of auxiliary data, which can improve performance.

• Main Advantage: By combining RAID 1 and RAID 0, complementary advantages are formed. While improving performance, it can also provide higher fault tolerance, which is very suitable for servers that require a large amount of data to be written.
• Main Disadvantage: This level requires too much cost, at least 4 hard drives are required, and the overall cost is at least twice that of other levels. In addition, RAID 10 can only use half the capacity of all hard disks. If a large amount of data is written, the demand for hard disks is very high.

What is AHCI?

The Advanced Host Controller Interface (AHCI) allows computer hardware vendors to exchange data between host system memory and storage devices. The technology adopted by AHCI is relatively advanced, with a variety of native functions of the SATA standard interface, such as Native Command Queuing (NCQ) and hot swap, etc., which can further improve the compatibility and performance of the device, so it is more common in newer computers.

AHCI is more suitable for hardware designers and software designers because it provides a standard method for detecting, configuring and programming SATA/AHCI adapters. It is worth mentioning that when AHCI is not enabled on the motherboard and chipset, the SATA controller will run in IDE (Integrated Drive Electronics) mode, which means that device functions that do not support the IDE standard will not be allowed to be accessed.

Currently, Windows, Linux, Unix and other operating systems all support AHCI. It should be noted that if you want to run Windows 10 on a solid-state drive, you need to enable AHCI before the system is installed. Otherwise, even if Windows 10 is successfully installed, you will still not be able to boot and a blue screen of death (BSOD) error will occur.

After understanding the concepts of RAID and AHCI, you may still have doubts about which one is better. Don't worry, I will introduce the difference between the two next.

RAID vs. AHCI

If you are still struggling with the question of which is better, RAID or AHCI, please continue to read the following content. We will introduce you to the difference between RAID and AHCI in terms of historical development and performance differences. First of all, we can use the table to list the differences between the two.

In short, RAID, as a widely used data storage technology, can enhance performance by combining multiple hard drives. And AHCI is an advanced SATA operation mode that can improve the compatibility and performance of the device.

History Development

AHCI was born in 2000 and has gradually replaced the traditional IDE model since 2007. The latest specification version is 1.3.1. With the rapid development of interface technology today, although AHCI is not an old technology and has some of the functions of the SATA standard, NVMe is a better substitute for current SSDs.

In contrast, the history of RAID development is much longer. As early as the 1970s, David Patterson proposed the concept of RAID. It was not until the development of RAID 1 that the technology was named Redundant Array of Inexpensive Disks. In 1977, IBM filed a patent later called RAID 4. In 1986, IBM again filed a patent that later became known as RAID 5. After RAID has really developed and grown, industry manufacturers have redefined the technology and changed its name to "Redundant Array of Independent Disks."

Performance Difference

Although AHCI and RAID modes have obvious effects on memory, motherboards and storage devices, for most users, the impact on hard drives is the key. Therefore, the following discussion on AHCI and RAID performance is limited to mechanical hard drives and solid state drives.

AHCI is widely used in storage devices with SATA interfaces. If you are using a SATA interface mechanical hard drive or SSD, you can choose to set it to AHCI mode, which is also a suggestion given by many SSD manufacturers. However, from the results of user feedback, the AHCI mode has little effect on the performance of the SSD, but will affect its service life. It is recommended to choose carefully.

RAID allows you to combine multiple mechanical hard drives or SSDs into an array, which can increase data read and write speed and provide data protection. Hardware RAID control mode and Software RAID control mode will directly affect performance, and different RAID levels will also cause performance differences.

Note✍: Although the RAID mode allows you to use both solid-state drives and mechanical hard drives at the same time, this method has little performance improvement and easily damages the stability of the array. Therefore, it is recommended to use the same type of hard drives in the RAID mode.

Is RAID Better than AHCI?

Which is faster, RAID or AHCI? It depends on the type and number of hard drives you are using. If you are using multiple hard drives, then RAID will be a better choice. It can combine multiple hard drives to form an array to provide you with faster read and write speeds and higher fault tolerance.

If you are using an SSD with a single SATA interface, then AHCI will be a better choice. Although this mode does not greatly increase the speed of the hard drive, it is still more suitable for a single SSD than RAID. To put it simply, you can choose RAID or AHCI according to the following scenarios:

✡ You are using an SSD with SATA interface, it is recommended to choose AHCI.
✡ You are using multiple hard drives (with SATA interfaces), and RAID is recommended.
✡ Your hard disk is already in RAID mode. Even if you continue to add new hard disks, it is still recommended to use RAID.

RAID vs. AHCI FAQ

You may still have some questions about RAID and AHCI, don't worry, we will answer common questions for you next.

How to Update SATA AHCI

1. Right-click on the Windows logo and select Device Manager from the expanded menu.
2. Find and expand IDE ATA/ATAPI controllers, right-click Standard SATA AHCI Controller, and select Update driver from the expanded menu.

3. In the pop-up window, select the option Search automatically for updated driver software, and wait for the search to complete and update automatically.

How to Switch from RAID to AHCI in Windows 10

1. Type cmd in the taskbar search box, find and select Run as administrator in the right window.
2. Type the following command in the command prompt window and press Enter to execute this command:

 ▶ bcdedit /set {current} safeboot minimal

3. Restart your computer, and press the corresponding button to enter the BIOS (the BIOS entry method for motherboards of different brands is different).
4. In the BIOS settings, change the SATA operating mode to AHCI, save and exit. And Windows will automatically enter the Safe Mode.
5. Right-click on the Windows logo and select Command Prompt (Admin) from the menu.
6. Enter the following command in the command prompt window and press Enter to execute this command:

  ▶ bcdedit /deletevalue {current} safeboot

7. Restart your computer again, at this time, your SATA operating mode will be changed to AHCI.

How to Set Up RAID

1. Restart your computer, and press the corresponding button to enter the BIOS (the BIOS entry method for motherboards of different brands is different).
2. Find SATA Mode under SATA Configuration. And click the option next to it to change the SATA mode to RAID mode. Save the changes and exit, just wait for the computer to restart.

Summary

If you are struggling with RAID vs. AHCI which is better, I suggest you read this article in detail. You can learn about the concepts of RAID and AHCI from the article, and have an in-depth understanding of their historical development and performance differences, allowing you to choose a more appropriate mode according to the type and number of hard drives used.

When you use a SATA interface SSD, it is recommended to choose AHCI. When you use multiple hard drives with SATA interface, it is recommended to choose RAID. In addition, it is not recommended to mix mechanical hard drives and solid state drives in RAID mode.