Hardware RAID vs Software RAID
RAID, commonly known as a “redundant array of independent disks,” is a method that’s used for virtualizing multiple independent hard disks into one or more arrays to increase performance, increase capacity, add fault tolerance, and improve reliability. RAID can be performed via hardware or software. This post will explain what hardware and software RAID are, as well as discuss the differences between hardware RAID vs. Software RAID in much detail. Also, we will explore the different RAID configurations that are available to you.
What is Hardware RAID?
Hardware RAID uses a dedicated RAID controller to manage a raid configuration. That is, the RAID controller manages and performs all tasks related to the RAID independent of the OS (operating system). With hardware RAID, the RAID controller configures the physical array, virtual disks and initializes them for use.
Also, the RAID controller is responsible for checking the disks for consistency and allocating the data between the physical drives. If one of the physical drives fails, the RAID controller is responsible for rebuilding a failed array for data consistency.
Hardware RAID controllers are what control hardware-based RAID. Typically, hardware RAID controllers are inserted into the PCIe slot of a PC’s motherboard. RAID controllers usually support a variety of different RAID configurations.
Now that we have explored hardware RAID let’s take a quick look at software-based RAID.
What is Software RAID?
True software RAID is usually performed via software deployed on an operating system. That said, software RAID can also be performed outside the OS using BIOS-based software RAID. BIOS-software RAID is configured via software on the BIOS level. Regardless of whether RAID is configured via the operating system or the BIOS, both forms are considered as software RAID, and both place a burden on a system’s CPU. This is different from hardware RAID, where processing occurs on a separate RAID System.
What are the Differences Between Hardware RAID vs. Software RAID?
The major difference between hardware vs. software RAID is that with software RAID, the software is responsible for managing RAID, whereas, with hardware RAID, a dedicated piece of hardware known as a RAID controller is installed in a system to manage RAID. Those who oppose software-based RAID cite the reason that software RAID places a burden on the CPU, reducing the system’s compute performance since processing power is taken away from the main system to manage RAID. However, such claims are overstated, especially when performing simple RAID applications, such as RAID 0 and RAID 1. This is so because computer processing power has come a long way and CPUs are extremely powerful. So, performing software RAID will not have a noticeable impact on the performance of the system.
Software RAID (Pros & Cons)
Let’s explore some of the advantages and disadvantages of using software RAID.
Advantages of Software RAID
Cost – The biggest advantage that software RAID has over hardware RAID is the cost. Since there is no need to invest in a hardware RAID controller because you are using software-based RAID, you will save money.
Processing Power – Most systems today are equipped with powerful processors, allowing them to manage RAID without having a noticeable impact on the system’s performance.
- Supports More Drives – Software RAID supports more drives than hardware RAID.
Disadvantages of Software RAID
Speed – Software-based RAID is sometimes slower than hardware-based RAID. This is so because hardware RAID utilizes dedicated hardware to manage a RAID configuration. Software RAID is slower because the CPU is tasked with running the operating system, applications, and managing RAID. Thus, it takes away performance from the main system.
Compatibility – Software RAID does not work very well for disks that are shared by different operating systems.
Support – Some operating systems only support a limited amount of RAID configurations. For all configurations, you should invest in a decent RAID controller.
Replacement – Replacing a failed disk can be quite complicated with software RAID.
Migration – RAID can only be implemented on a single system, making it difficult to migrate the RAID array to a different OS or even other versions of the same OS.
- Algorithm – Software RAID requires a good algorithm to achieve decent performance. Without a good algorithm, software RAID performance will suffer.
Hardware RAID (Pros & Cons)
Let’s explore some of the advantages and disadvantages of hardware RAID.
Advantages of Hardware RAID
Performance – Hardware RAID tends to be faster than software-based RAID because it has a dedicated RAID system to manage the RAID independent of the operating system (OS), which means that it will not bog down the main system since the RAID processing is offloaded from the main system to a dedicated RAID controller card. Hardware RAID is especially beneficial for use in legacy equipment that has limited processing power. This is so because add-in RAID controllers will take on the task of managing the RAID array, which means less strain on the CPU of the system.
Additional Configurations – Hardware RAID often has more configurations than those offered by software-based RAID. Motherboards often offer a few options, so investing in a hardware RAID card will provide you with additional RAID configurations that would otherwise be unavailable to you.
Compatibility – Hardware RAID offers better compatibility across different operating systems than software RAID. For example, if you plan on accessing your RAID system from two different operating systems, such as Mac and Windows, you’re better off choosing a hardware RAID configuration.
Less Use of System Resources – Hardware RAID places less stress on the system when performing backups and recovery operations. This is so because such processes are handled by a dedicated RAID system that does not stress the main system’s CPU.
Battery Backup – Hardware RAID offers protection from data loss and data corruption in the event that a power outage occurs because RAID cards often have batteries that protect the cache and memory.
Viruses – Hardware RAID Cards are not vulnerable to viruses since the RAID system is completely separate from the host system.
- Encryption – New raid controllers come with hardware-based encryption mechanisms to protect the data on the drives.
Disadvantages of Hardware RAID
Cost – Hardware RAID cards are more costly than software RAID because you have to invest in dedicated hardware to manage your RAID array. Additional hardware is not needed for software RAID, making it a less costly alternative.
Replacing a RAID Card – Another disadvantage associated with using a dedicated RAID card can be seen in the event that a RAID controller fails. If the RAID controller fails, you will need to find a compatible RAID card to replace it with to maintain your previous configuration.
- Bottleneck – The performance of a system can be bottlenecked by the performance of the RAID card.
What are the Different RAID Configurations?
The two most popular RAID configurations are RAID 0 and RAID 1. If you’re using either of these RAID configurations, you will not notice a significant difference between using software or hardware RAID. We will now discuss the most popular RAID configurations.
1. RAID 0 (Striping)
RAID 0 is known as striping or a striped volume, and it involves dividing data into blocks and spreading the blocks of data across multiple storage devices. This results in the contents of a single file to be striped across a number of disks, increasing the speed of data write speeds. However, the increase in performance comes at a cost. This is so because if one of the drives in the array fails, all of the data is lost since data is striped (distributed) across multiple disks. RAID 0 is ideal for extracting the most performance from your storage devices. However, RAID 0 should only be used for non-critical data storage. For example, if you have a system that you use for editing videos, you can use RAID 0 because of the performance boost it offers in terms of reading and writing data. However, you should not store critical information because a failure of one drive will cause you to lose all of your data.
2. RAID 1 (Mirroring)
RAID 1 is known as mirroring, and it involves duplicating the data on one drive to another drive for redundancy. Raid 1 is excellent for making a copy of your data onto another drive, offering you the ability to recover your data in the event that a single drive in an array fails. Simply stated, RAID 1 involves writing the same data to two drives. If one of the drives fails, the RAID controller can use the good drive to duplicate the data to a new drive, thus making data recovery quick and simple.
This makes RAID 1 great for critical data because you will always have a copy in the event that one of the drives fails. That said, by utilizing RAID 1, your drive capacity is half of the total drive capacity because the same data is written twice. For example, if you install two 500GB SSDs to your system and choose a RAID 1 array, your system will see a single 500GB hard drive while writing the same data to both storage devices.
Again, RAID 1 is great in the event that one of your drives fails, the data will immediately be available on the second drive, allowing your system to continue to operate without experiencing any downtime.
Furthermore, another advantage of RAID 1 is the increased speed in data reads. This is so because your system can read the same data from both drives simultaneously, increasing the read speed of your system. Unfortunately, write speeds are not increased because your system must first write data one drive, and then mirror the data onto the second drive.
3. RAID 5 (Striping with Parity)
RAID 5 requires three or more hard drives. It uses RAID parity to protect your data while providing you with a performance boost. RAID 5 stores data on multiple drives, allowing the system to read data from multiple drives. However, in a RAID 5 configuration, you will lose the capacity of one drive. For example, if you add three hard drives, RAID 5 will stripe data across the drives and store parity bits across all three drives, splitting the data among all three drives. In the event that one of the three drives fails, the data will not be lost as the RAID controller can use RAID parity (bonus data) to reconstruct the data that was lost on one of the drives. Of course, to store parity data, you will need to sacrifice a single hard drive’s storage. Thus you need a minimum of three hard drives for RAID 5 to work.
4. RAID 6 (Striping with Double Parity)
RAID 6 is just like RAID 5, but it requires a minimum of four hard drives to function. This is so because it uses two sets of parity data instead of the one set used by RAID 5, allowing RAID 6 to sustain a loss of two drives without an organization losing any of its data. That said, it is highly unlikely that two of your drives will fail at the same exact moment, but if they do, you will not lose any of your data, as your system can rebuild the data that was on the drive that failed. So, if you want more redundancy and security for your data, you should use a RAID 6 configuration because it is more secure than RAID 5. Furthermore, RAID 6 offers faster read speeds than RAID 5 because data is stored on more drives, allowing the system to read data simultaneously for increased read speeds.
5. RAID 10 (Combines RAID 1 & RAID 0)
RAID 10 combines RAID 1 and RAID 0, creating a hybrid RAID configuration. It provides security by striping data across each set of drives and mirroring the data on the second set of drives, offering organizations the best of both worlds. If any of the drives fails, RAID can rebuild a drive very fast since the data only needs to be copied from the surviving mirrored drive. That said, you will lose half of your drive storage since your mirroring data, making RAID 10 more expensive than RAID 5 and RAID 6.
Raw Capacity vs Usable Capacity
When using RAID, you should be aware that there may be a difference between the raw capacity of your drives and the usable capacity you will be able to use to store your data. The usable storage you will have depends on the RAID level that you decide to use. For example, if you use RAID 1, although it’s great for protecting your data, you will lose half of your drive capacity. For example, if you have two 1TB hard drives, giving you a total raw capacity of 2TB, you will be left with 1TB of usable storage capacity.
That said, with RAID 0, you do not lose any of your data because data is striped on both drives, making your usable capacity the same as your raw capacity. However, the downside is that if one of your drives fails, you lose all of your data.
With RAID 5, you need a minimum of three drives. When using RAID 5, if you have three drives, you will lose the capacity of one of the drives because some of the storage will be used to store parity bits. Parity bits are stored on all of the disks so that data can be reconstructed in the event that one of the disks fails. For example, if you were to place three 1TB drives in RAID 5, giving you a total raw capacity of 3TB, you will be left with 2TB of usable capacity.
RAID 6 is similar to RAID 5 with one difference, instead of using 1 parity stripe, RAID 6 uses two parity stripes. RAID 6 requires a minimum of four drives and can sustain a loss of two drives at the same exact time. For example, if you have 5x 1TB drives, providing you with a total of 5TB of raw capacity, 2 disks worth of parity data will be unavailable, providing you with a total usable capacity of 3TB.
Frequently Asked Questions (FAQs)
1. How many disks are required for RAID?
For RAID 0 and RAID 1, you need a minimum of two hard drives for it to work. However, for RAID 5, you need a minimum of three hard drives. For RAID 6, you need a minimum of four hard drives. The amount of hard drives or SSDs that you will need depends on the type of RAID that you’re using.
2. Which RAID offers the fastest read/write speeds?
RAID 0 is the fastest RAID type; however, it should only be used for non-critical information because if one of the drives fails, you will lose all of your data. This is so because data is striped on both drives, so the loss of one drive is equal to the loss of all of your data.
3. Which RAID offers the best storage capacity?
RAID 0 offers the best storage capacity because there is no redundancy and no reason to mirror data. Instead, RAID 0 only stripes data across two drives, allowing organizations to take full advantage of the entire storage capacity of all drives. However, RAID 0 should not be used for mission-critical information because a failure of even one drive will result in a total loss of data.
4. Is RAID 0 or RAID 1 Better?
The option that’s best for your workload depends on what you expect from your RAID arrangement. RAID 0 offers extremely fast data transfer speeds but offers no fault tolerance, nor does it offer data redundancy. RAID 1, on the other hand, offers mirroring, allowing the same data to be stored on two drives. Storage of data on both drives does offer a boost in performance for data read speeds; however, it results in a loss of half of your data storage to allow for the mirroring of the data. However, when it comes to write speeds, RAID 1 is slower than RAID 0 since the data has to be written twice for mirroring purposes.
5. How much storage do you lose with RAID5?
If you add three hard drives for a RAID 5 configuration, you will lose the equivalent of one storage drive. So, if you were to add three 2TB drives with a total capacity of 6TB, you would lose 2TB of capacity if you were to choose a RAID 5 configuration.
6. Which RAID is best?
If you want performance and redundancy, you should configure your system with a RAID 5 configuration. Redundancy is available because your system could sustain a loss of one drive without the loss of any data.
7. What is Intel chipset raid?
Intel chipset RAID is a firmware-based RAID solution that is built into a large number of Intel chipsets. It is capable of RAID 0, 1, 5, and 10.