Redundant array of independent disks (RAID) is the logical grouping of two or more disks to give you benefits such as enhanced performance, fault tolerance, data redundancy, and more. These benefits depend to a large extent on the way you configure these disks, with some of the popular RAID configurations or levels being RAID 0, RAID 1, RAID 5, RAID 6, and RAID 10. In this article, let’s pitch RAID 1 against RAID 5 to understand which of the two is better in which situations.
RAID 1 configuration is a fairly simple one as it stores identical data on two or more disks for better data redundancy. In a RAID 1 configuration, every data is written to both the disks simultaneously while the read operations are fast as the data is read from two or more disks at the same time. This offers data redundancy and works well when you’re dealing with mission-critical data. Simply put, RAID 1 does mirroring where the same data is copied to two or more disks. Let’s take a brief look at its advantages and disadvantages.
The advantages of RAID 1 are:
- RAID 1 offers fast read performance at speeds comparable with RAID 0, especially if the RAID controller uses multiplexing to read data simultaneously from many disks.
- It is ideal for mission-critical data where data loss can have disastrous consequences.
- It provides improved performance, even if the write operations tend to be a bit slower.
The disadvantages of RAID 1 are:
- RAID 1 requires twice the storage space, and this can prove to be expensive.
- Accessing data from the failover disk is not automatic, and the system has to be shut down to fix the secondary disk, in case of failure of the first one.
- There are no security measures in place.
RAID 5 also offers fault tolerance like RAID 1, but instead of using mirroring, it uses parity and checksum where the data is striped and stored evenly across all disks, along with their parity, so the data can be reconstructed at any time.
The advantages of RAID 5 are:
- Read operations are fast and can serve multiple users at the same time.
- Provides a high level of data redundancy.
- Efficient utilization of disk space since the RAID controller uses parity to rebuild data. There is no data duplication, and hence, disk space can be used better.
- The system doesn’t have to be shut down when a disk fails as the parity information is used to rebuild this data.
Some of the disadvantages of RAID 5 are:
- The write operations are a bit slow because parity has to be calculated. Of course, this parity information is also distributed, so there are no bottlenecks like RAID 4.
- Requires a minimum of three disks.
- Recovery operations are a bit slower because of parity calculations.
Now that we have a fair idea of RAID 1 and RAID 5, let’s stack it up against each other to assess the performance.
RAID 1 vs. RAID 5
Let’s compare the performance of RAID 1 and RAID 5 through common operations and features.
|Read||Read is fast in RAID 1 because read requests are sent to parallel drives and the one with the fastest performance returns the data first||Read is extremely fast in RAID 5 too because data is accessed quickly and sent back to the user.|
|Write||Write operations are slower than reading since the same data has to be written across multiple disks||Write operations are slow in RAID 5 too because the parity information has to be calculated during each write and this takes time.|
|Fault tolerance||Fault tolerance is good since more than one disk contains the same data. However, in the case of a write operation, both the disks can get corrupted which will eventually result in a data loss.||Even if one system fails, the data will be reconstructed using the parity information. Though read and write operations may be slow during this data reconstruction, there is no need to power down the system.|
|Data storage||Only 50% of the data capacity can be used since the same data has to be written across both the disks||About 4/5th of the disks will be used and only the remaining one will be used for storing parity information.|
|Applications||Data archival and any other application that stores or uses mission-critical data||File and application servers as they require a good balance between storage, performance, security, and failure resistance.|
|Data storage||Data is not divided into two disks and the same data is just mirrored, so each disk has an identical copy.||Data is split evenly across all disks.|
|Number of drives||If you plan to use only two drives, RAID 1 is the most efficient implementation.||RAID 5 can support up to 16 drives.|
|Extra cache||Implementing extra cache is difficult in RAID 1 because it is hardware-based||An extra cache can be easily implemented in RAID 5|
|Security||Low security||Good security and decent performance because of parity checking.|
So far, we have seen the two RAID levels, their advantages and disadvantages, and how they stack against each other in common operations. Let’s now take a look at some real-time scenarios and which of the two would work best in each.
File and application servers
RAID 5 works best for file and application servers because storage is optimized and highly efficient. Also, RAID 5 servers don’t use mirroring, and even the parity is split across different disks, depending on the setup. Hence, RAID 5 can be easily implemented even if the file servers have lesser drives.
Continuous data access
If you need continuous data access, RAID 5 is the best choice as the data is automatically reconstructed in the event of a disk failure. In RAID 1, you have to turn off the system to replace the corrupted drive with the secondary one. In other words, hot-swapping the corrupted drive with a secondary one is easy in RAID 5, and it comes with parity checks as well. Though you can implement hot swapping in RAID 1 with hardware controllers, it’s not easy.
RAID 1 is the right choice for those who are setting up a RAID 1 at home or for basic applications at work. This is a simple technology that requires no complex set up and hence, works well for basic read/write operations.
Installing an operating system
You can install an operating system only on RAID 5 and not on RAID 1.
As you know, any RAID level can be implemented through hardware or software, and each comes with its share of advantages and disadvantages. If you’re looking to tap into the advantages of a hardware-based configuration, RAID 1 is your choice because RAID 5 is best implemented through software.
If you’re on a tight budget and can choose from either level, go for RAID 5 as it is cost-effective since it optimizes storage. Also, it has zero downtime.
Accounting systems handle critical data, and undoubtedly, RAID 1 is the choice because of its high reliability. Thus, these are some of the real-time scenarios when you can use these RAID levels.
RAID 1 or RAID 5? Now you know
To conclude, RAID 1 is a simple implementation, whereas RAID 5 is a more complex one because of the varying underlying technologies in each of the implementations. The exact choice depends on the scenario and what features or aspects it needs.
We hope the above information will help you to make an informed choice between RAID 1 and RAID 5. Please tell us in the comments section the scenarios in which you have used either to better help our readers to decide between the two RAID levels. And check out the rest of our series on RAID levels by clicking on the links below.
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More RAID levels articles
- Hackers: the New Ghosts in the Machine
- RAID 5 vs. RAID 6: When to use each level and why
- RAID 10 vs. RAID 5: When to use each level and why
- RAID 0 vs. RAID 1: When to use each level and why
- Hardware RAID vs. software RAID: Pros and cons for each