StallionTek Blog Post

Advantages and Disadvantages of RAID Levels

By | Aug. 09, 2018

Business owners have many features to consider when choosing the right system and infrastructure for your critical online applications. One of the features you have to consider when choosing the right server for your business is what type of RAID to choose to fit your technical needs. Below we will go through all the pros and cons of each RAID level and how it might affect your current set up as well.

RAID stands for Redundant Array of Independent Disks, and is a subsystem that stores your data across multiple disks to either increase the performance or provide fault tolerance to your system. Some RAID levels have the advantage of providing both however they also come with a larger requirement as well.

RAID can be configured either through hardware or through software. Hardware RAID is directly managed by a dedicated RAID controller that the drives are connected to. The RAID calculations are managed by an on-board processor which offloads the strain on the host processor CPU. RAID controllers do provide an extra failsafe element with its battery backup unit that protects your data in case of an unexpected power loss to the server.

RAID configured through software is part of the operating system and is a much easier process to accomplish. Configuring it through software also does not require any additional equipment beyond the operating system which makes it a cheaper option as well.

Below are the most used RAID configurations:

RAID 0 (Disk Striping):
RAID 0 splits data across the disks allowing higher data throughput. An individual file is read from multiple disks giving it access to the speed and capacity of all of them. RAID 0 benefit of increased performance and is referred to as stripping. The downside is that it does not facilitate any kind of redundancy and fault tolerance, as it does not duplicate data or store Information. It combines your disks into a single giant storage space however when one drive fails, so does the rest of the configuration and data is lost. RAID 0 is usually implemented for live streams and other files where speed is important and reliability/data loss is secondary.

Minimum number of disks: 2
Pros: Increased performance (Write and read speeds).
Cons: No redundancy.
Enterprise Purposes: Live streaming, IPTV, VOD Edge Server

RAID 1 (Disk Mirroring):
RAID 1 writes and reads identical data to pairs of drives. This is the most basic for of redundancy, it uses half of your disk space to create a mirror format storage process as is in the name. It saves onto both halves, and once one fails, the other continues to operate. This allows you to easily replace the defective drive and continue operations as normal. Once replaced it will mirror once again and go back to being redundant just like before.

Minimum number of disks: 2
Pros: Fault tolerance and easy data recovery. Increased read performance.
Cons: Lower usable capacity. Higher cost per megabyte (double the amounts of drives is required to achieve desired capacity).
Enterprise Purposes: Standard application servers where data redundancy and availability is important.

RAID 5 (Striping with parity):
RAID 5 stripes data blocks across multiple disks like RAID 0 while storing parity information. Parity is small data that is used to connect to larger data blocks and recover data when disk failure occurs. This gives the speed of a RAID 0 configuration while having some data safety. When the disk fails, the data is created from the parity information that was created for redundancy. Where RAID 1 uses half of your drive capacity, Raid 5 only uses 1/3.

Minimum number of disks: 3
Pros: Fault tolerance and increased performance (lower than RAID 0)
Cons: Lower performance with servers performing large amounts of write operations because of parity overhead.
Ideal use: File storage servers and application servers.

RAID 6 (Striping with double parity):
RAID 6 is the same as Raid 5 but has double the Parity storage. It protects in the case of 2 drives failing instead of 1 drive failure. This is why it also shares the same pros and cons as a Raid 5 Configuration.

Minimum number of disks: 4
Pros: Even higher redundancy than RAID 5. Increased read performance.
Cons: Lower performance with servers performing large amounts of write operations because of parity overhead.
Ideal use: Large file storage servers and application servers.

RAID 10 (Striping + Mirroring):
RAID 10 combines the mirroring of RAID 1 with the striping of RAID 0. This way it has the redundancy of the RAID 1 (which RAID 0 lacks) and the performance of a Raid 0 (which is what a Raid 1 tends to lack). Its like getting the best of both worlds. It is best suitable for needs where both high performance and security is required.

Minimum number of disks: 4
Pros: Very high performance. Fault tolerance.
Cons: Lower usable capacity/High cost. Limited scalability.
Ideal use: Highly utilized database servers/ servers performing a lot of write operations.

When it comes to RAID, there are a lot of benefits to protecting your data. As great as some of these RAID Configurations are, they are not a complete package. Critical data and important files should always be backed up on a separate drive or system. RAID is great for protecting against corruption and errors but ALWAYS create a backup of your information. The StallionTek team is always here to help you with any of your configuration requirements or technical support needs!

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