RAID 1 vs RAID 5: A Race Where Speed Isn’t Everything

The vast majority of modern businesses have heavily integrated computer systems into their everyday workings. While this has rocketed many companies to greater heights, the systems that are truly responsible for their success are their central servers, storing and distributing vast amounts of data whenever required. In order for these servers to exist, they must use RAID technology, allowing them to seamlessly interlink multiple hard drives for purposes such as greater performance and data protection. In this article, we are going to look at RAID 1 vs RAID 5, and the key differences between the two setups.

What Is RAID 1: Data Replication

Raid 1 was designed with data recovery in mind, and uses a protocol called mirroring in order to achieve it. Mirroring causes the computer to write a copy of any information saved to it on a second hard drive, creating a perfect replica. This means that if one hard drive fails, the other can be used to recover any data that was lost. Due to a higher cost, this setup is typically used by businesses with larger budgets.

RAID 1 drive setup illustration


Let’s say you have a file of 100 GB in size, and you are saving it to a computer with two hard drives using a RAID 1 setup. Whether you save the file to the computer, or create the file on the computer, a copy will be simultaneously created on the second drive. This means that any file will require twice the storage space, but will be easily recoverable if lost.

Advantages of RAID 1

  • Excellent read/write speeds. Can use a RAID controller with multiplexing to read data from multiple disks.
  • You do not need to rebuild data if a drive fails, just copy the data over to the replacement drive. The recovery process is simple and rapid, making it an excellent option for those who need cheap, high fault tolerance.
  • RAID 1 is simple technology to implement since it does not use a disk with a parity check system.
  • Expandable with more disks to add extra redundancy.

Disadvantages of RAID 1

  • Since data is written multiple times, the storage capacity is half or 50% of the total capacity of the smallest drive.
  • If a disk fails, the system must be shut down so that the failed disk can be repaired or swapped out.

What Is RAID 5: Recovery Without Redundancy

The creation of the RAID 5 system was meant to bridge the gap between drive performance and redundancy. Much like RAID 0, it uses a process called striping, which separates data into equal portions and distributes them sequentially across multiple drives. Additionally, It utilizes a feature called parity, which is data used to calculate what a file would contain if the original file is lost.

Parity is not a backup system, rather a filing system that knows what data is where, allowing it to check whether the information in a given file contains everything it’s supposed to. For added security, RAID 5 builds on earlier RAID levels by also striping its parity system, meaning the parity data for a given file is stored on a separate drive than the file itself.

RAID 5 drive setup illustration


Raid 5 is fundamentally different from RAID 1, so we’ll have to change our example slightly. Consider several files, A, B and C, each to be broken in half and stored on a computer using three drives and a RAID 5 setup. What you would see would resemble the chart below:

Disk 1Disk 2Disk 3
A1A2A Parity
B1B ParityB2
C ParityC1C2

As you can see, the file A, B and C are still stored sequentially, but with parity portions among each. This looks confusing at first, but actually allows the computer to run almost as quickly as a similar RAID 0 setup, while still maintaining data security comparable to that of RAID 1 without needing to copy any information.

Let’s take this a step further and say that disk 2 fails and all the data is lost. This means we’ve lost files A2, C1 and the Parity data for file B. The parity data for files A and C still exists on the other drives, so those files can be recovered, and since only the parity data for file B was lost, it can simply be rebuilt once a new drive is installed.

Advantages of RAID 5

  • Has excellent read speeds and can provide services to multiple users at once.
  • Has good data redundancy.
  • Parity information is used to rebuild data during disk failure. No need to shut down the system. You can still access the data even if you replace the failed drive.
  • In a RAID 5 set up, the RAID controller uses the parity information to rebuild the data, so there is no data duplication required. This is why more of your disk storage space is accessible.

Disadvantages of RAID 5

  • You need a minimum of 3 disks to implement this setup.
  • The writing performance can be a little slow.
  • It can take quite a lot of time to rebuild data if a large disk fails. If another disk is damaged during the recovery process, all data is lost.
  • During a drive failure, the read/write speeds will be significantly reduced as the system is actively restoring information.

RAID 1 vs RAID 5 Comparison Chart

Key FeatureDisk MirroringDisk Striping With Parity Check System
Storage Disks Required23 or More
Storage Capacity50%80%
Parity Check SystemNoYes – Parity Data is Across All Drives
Fault ToleranceYesYes – 1 Drive Can Fail
Data RecoveryYesYes – Using the Parity Check System
Overall CostMuch Less ExpensiveExpensive
Disk Read PerformanceSame or Slightly Higher Than a Single DiskFairly Quick
Disk Write PerformanceVery SlowFairly Quick
Write Penalty?Yes – ModerateYes – Slightly Due to Writing to the Parity Block
Appropriate PurposeData Security – Where Data Loss is UnacceptableA Balance Between Speed & Data Security

RAID 1 vs RAID 5 Critical Distinctions

  • RAID 1 uses disk mirroring, while RAID 5 uses parity striping.
  • RAID 1 is cheaper to set up because minimum disk requirements is 2, while RAID 5 can be a bit more expensive due to needing a minimum of 3 disks.
  • RAID 1 storage is 50%, while RAID 5 can achieve 80%.
  • Raid 1 has a relatively slow write speed, slower than using a single disk. RAID 5 has a write speed much faster than a single disk, but lags slightly due to the need for creating parity data.
  • RAID 1 has a higher write penalty as it has to write a copy of all data for every additional disk present. RAID 5 has a comparably lower write penalty due to using striping, but the need for parity data raises the penalty slightly.
  • Both RAID 1 and 5 use striping, so all data is stored across all drives, however, RAID 5 has to spread non sequential data out more to make room for parity data.

Use Cases: When to Use RAID 1 in Real Life Scenarios

RAID 1 is a must where critical data is being stored and the risk of loss has to be minimized. For this reason, it is generally used by massive organizations like hospitals, schools, and law firms.

Electronic Databases

RAID 1 can easily deal with the traffic from multiple users.

Financial Systems

In circumstances like payroll and accounting systems, data loss would be catastrophic, and so these systems need a storage set up that will protect them against data loss.

Enterprise Web Servers

If key tools of these web servers were to be lost, this would severely cripple operations.

Use Cases: When to Use RAID 5 in Real Life Scenarios

RAID 5 is a great balance between speed and safe storage, making it great for businesses with higher needs and expectations. Commonly used for enterprise and business file and application servers that have a limited number of data drives in use.

Frequently Asked Questions

Why is RAID 5 not always recommended?

If you are running a RAID 5 setup that has a lot of large disks, and the data information gets lost, you have a greater risk of losing your entire array. This is because there is no duplicated information in a RAID 5 setup, meaning you are solely relying on the parity check information to rebuild the correct data. If it doesn’t, you may lose another disk in the array and thus subsequent data.

Should you choose RAID 1 or RAID 5?

Although RAID 1 and 5 are fundamentally different, aspects such as speed and recovery potential can still be compared fairly easily. While the final decision should be made based on your needs, RAID 5 has proven appropriate where speed is still essential but recovery potential is necessary.

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