How does RAID 5 work?
RAID 5 is one of the most common RAID levels used by many people for home data storage and business (enterprise) data storage. This is because RAID 5 offers parity and redundancy to a reasonable extent, and it’s quite easy to set up compared to its closely similar alternative, RAID 6.
But, if you’re setting up RAID 5, you should be aware that its redundancy capability is not as reliable as normal backups; so, this shouldn’t make you feel lazy to do backups regularly. Interestingly, there are many software programs that let you back up RAID drives for free. This article explains everything you should know about RAID 5.
What is RAID 5 and How It Works?
RAID 5 is a type of RAID level that supports parity and data striping. When data is written into a RAID 5 array, the data is striped into bits and saved across all member drives, along with parity data. Each drive in RAID contains a unique bit of every data written into the logical storage and has a reserved block for parity data storage.
Unlike in RAID 0 where data striping is supported too, RAID 5 can survive single drive failures, thanks to the parity data it saves each time a new data is written to the logical volume. However, in a scenario where two drives fail in a RAID 5, your data in the array will become inaccessible and probably lost.
When a single drive fails in RAID 5, you can rebuild the array by simply removing the failed drive and installing a new one. No data will be lost because the system will read the parity data from the other drives to automatically recover the lost data and store it back on the new drive. This procedure may take quite some time to complete.
Advantages of RAID 5
The fault tolerance support and ability to recreate lost data in a RAID 5 system make it a good choice for most people. When a drive fails in RAID 5, you can replace it and the system will rebuild/recover the lost file automatically. Generally, RAID 5 is considered an overall good RAID system suitable for use in applications or file server storage. This RAID level offers faster read speed and data protection more than other RAID levels.
Disadvantages of RAID 5
No system is 100% perfect without a fault. While RAID 5 might offer faster read speeds, it offers slow write speeds; this is because parity data need to be stripped and written along with the actual data sent to the storage. Also, RAID can tolerate a single drive failure, but the process to rebuild the array after you have replaced the failed drive could take long hours, or even days to complete – depending on the data size to be rebuilt and RAID controller speed.
RAID Requirements for Disks
RAID 5 isn’t too complex to set up, but it requires at least three disks. It is advisable to use disks of the same specs, interface, and storage capacity. If you can, purchase, high-performance SSDs for the setup to improve write speed to a significant extent.
Features of RAID 5
The core features of RAID 5 are data redundancy (fault tolerance) and parity distribution which comes in to help when there’s a single failed drive in the array. However, there are other features of RAID 5 worth talking about.
1. How Data Striping and Parity Occurs in RAID 5
Being the core features of RAID 5, it is important that you understand how striping and parity work on this RAID system. As you write new data to a RAID 5 storage, the storage picks up the data and strips it into bits, which are distributed to all drives used in the array. However, as the RAID strips the original data, it also creates parity data, which it distributes evenly across the entire disks in the array, too.
So, every drive in the array will contain a chunk of data bits along with a reserved block of parity data. The parity data is distributed across the member drives to serve as a “failsafe” the system could fall back if a sudden catastrophe hits the array and one drive fails; now, with the help of the parity data, the system will continue to function even with the failed drive – this is helpful for business continuity even in an event of critical hard drive failure.
2. Multiple Advantages for Home and Business Use Cases
- Allows more storage space to be used since there is no dedicated drive for parity data.
- Fosters business continuity in scenarios where a hard drive fails suddenly with no prior signs shown.
- Cost-friendly and can be built with just three drives
- Offers a good balance between speed, performance, fault tolerance, and redundancy
- Suitable for many use cases in home and business environments
- Automatically reconstructs lost data from the saved (distributed) parity data.
- Faster read speed due to striping
3. Two Drives Failure Can Lead To Total Data Loss
One of the appraised features of RAID 5 is the fault tolerance against single drive failures. On the flip side, if two drives fail simultaneously in a RAID 5 system, the RAID will shut down and your data will be lost. Even if you replace the two drives, the system won’t rebuild itself – you have to do the rebuilding manually, which is more like reconfiguring the RAID 5 from scratch.
Also, even if two drives didn’t fail, and it’s just one drive, so the system remains functional – you will need to replace the one drive that failed pretty soon before another one joins the suite and causes total loss. But then, when you replace a failed drive in a RAID 5 system, it takes so much long time for the system to rebuild and restore lost data.
Although RAID 5 allows you more storage than RAID 2 and some other RAID levels, it does not allow you to utilize the full storage capacity of your data drives because it needs some space for storing parity data.
4. RAID 5 Use Cases
RAID 5 is typically used in applications where data continuity is needed; so, if even a drive in the array fails, data can still be accessed without any important file getting lost. That said, RAID 5 is the go-to RAID-level system for enterprise data centers, NAS systems, and most server environments. Of course, this RAID level can be used for other applications, including home data storage; it is flexible to an extent and offers a good amount of advantages over other RAID levels.
Differences Between RAID 5 Software vs. Hardware RAID 5
Compare and contrast software and hardware RAID 5 implementations, including performance implications, cost differences, and suitability for various applications.
| Feature | Software RAID 5 | Hardware RAID 5 |
|---|---|---|
| Cost | Typically less expensive as it uses existing CPU and system resources. | More expensive due to the need for dedicated RAID hardware. |
| Performance | Can be CPU intensive, potentially impacting overall system performance. | Generally offers better performance, especially for write operations, as it offloads operations from the CPU. |
| Setup and Management | Managed through the operating system or software tools, which can be less intuitive. | Often managed through a BIOS interface or dedicated software, potentially offering a more user-friendly and robust management interface. |
| Compatibility | Dependent on operating system support and might have limitations on portability between systems. | Usually independent of the operating system, offering a higher degree of compatibility and portability. |
| Reliability | Can be affected by system crashes or software issues, potentially leading to data corruption. | Generally more reliable as it is less susceptible to system crashes and often includes features like battery backup to protect data in case of power failure. |
| Features | May lack advanced features such as dedicated caching, battery backup, and hardware error correction. | Typically includes advanced features like RAID level migration, dedicated cache memory, battery backup, and hardware error correction, improving performance and data integrity. |
| Scalability | Limited by the host system's resources and capabilities. | Often supports expansion options like additional RAID arrays or larger disk configurations without taxing the host system's resources. |
| Bootability | Booting from a software RAID 5 configuration can be complex and is not always supported. | Hardware RAID allows for booting directly from the RAID array, offering more flexibility in system configuration. |
| Power Consumption | May increase overall power consumption due to the CPU handling RAID operations. | Power consumption is offloaded to the RAID controller, potentially reducing the load on the system's CPU. |
| Recovery | Recovery can be more challenging and dependent on the operating system's tools and support. | Often includes built-in diagnostic tools and recovery options, simplifying the process of data recovery in case of disk failure. |
What Other Common RAID Levels Are There?
There are many RAID levels that exist, each offering unique benefits and data processing techniques. Here are some popular RAID levels you need to know about:
- RAID 0: This RAID level supports data striping just like in RAID 5, but RAID 0 does not write parity data. So, upon a single drive failure, the enter RAID system will shut down and your data will be lost. However, this RAID level offers good read speeds.
- RAID 1: In RAID 1, data is mirrored across all member drives. This means all drives used in the array have the same data stored in them; thus, as long as there’s still one good drive in the array, the RAID storage system will continue to function. You only lose your data when all drives in the array have failed, and automatic rebuilding is not supported in RAID 1 as in RAID 5.
- RAID 2: Although RAID 2 is a standard RAID level and offers high speeds, it is not often used by many due to its complexity. This RAID supports bit-level stripping and uses Hammer Code parity for data recovery.
- RAID 3: This RAID level uses a dedicated parity disk to store parity information generated by the RAID controller, unlike in RAID 5 where parity information is stripped and distributed to the member drives along with the original data. Since parity data is saved differently, RAID 3 tends to offer slow read performance in small data requests. But this RAID level appears to be the best for applications requiring long sequential data transfers like video editing and streaming.
- RAID 4: This RAID level uses a dedicated parity drive too, and supports block-level striping across member disks in the array. RAID 4 shares similarities with RAID 5, but uses a dedicated parity drive, which could lead to a bottleneck for sequential write requests.
- RAID 6: In RAID 6, two drives are used for storing parity information, so you need at least four hard drives to set up this RAID level. Also, RAID 6 can survive multiple drive failures and still recover the lost data when the failed drives are replaced. But RAID 6 is slower than RAID 5 due to the additional parity drive.
RAID 10: RAID 1 + 0 (commonly written as RAID 10) is a combination of RAID 1 and RAID 0. You first set up RAID 1 pairs, then stripe both pairs as RAID 0. This RAID setup offers fast read and write speeds (due to the RAID 0 striping) and high redundancy (due to the RAID 1 mirroring).
Is Data Recovery from RAID 5 Possible?
Yes, sure. As long as it’s just one drive that failed when you replace the failed drive with a new one, the system will rebuild itself and reconstruct the lost data. But if you had multiple drive failures on your RAID 5 setup, then you need a third-party RAID recovery solution to recover your files from the RAID drives, individually.
Need RAID 5 Data Recovery?
Professional solutions like the DiskInternals RAID Recovery software can help retrieve files lost from RAID 5 drives. This RAID recovery software supports all known file systems and RAID controllers (both software and hardware controllers). It also features an intuitive interface, plus a Recovery Wizard to help users get through with the recovery processes, swiftly.
What Does Parity Do in a RAID 5 Array?
Parity information is used for data reconstruction and automatic rebuilding of the array in the event of a failed drive; this scenario is also called a “Hot Spare.” RAID 5 does not read or access parity information until there is a failed drive in the system.
How Does a Hot Spare Work in a RAID 5 Array?
A hot spare is a scenario whereby a RAID level is able to continue functioning even though one of the data drives has failed and stopped responding. This is possible because the RAID controller reads the parity data on the remaining good drives and uses this information to reconstruct the lost data on the failed drive and still allow the user to access the data. In data centers, this can minimize server downtime to the lowest possibility.
What is the Main Reason for Your Data Loss?
There are many reasons why data loss could occur, including human error and virus attacks on the system. RAID levels, although may offer data resilience and redundancy, are not immune to fatal data loss scenarios.
Some common causes of data loss in RAID levels are hardware failure, software problems, OS/system crashes, and power surges leading to logical damages to the hard drive partitions or dynamic volumes.
Well, most data loss situations can be reverted if you act quickly and use a professional data recovery software. DiskInternals RAID Recovery is a reliable RAID recovery software to keep handy for these scenarios.
Conclusion
What more? RAID 5 is one of the commonly used RAID levels, thanks to its performance speeds, data protection capabilities, and flexible configurations. You need only but three drives to set up RAID 5 using a hardware or software RAID controller. The automatic rebuilding capability is only possible when there’s just one failed drive.
FAQ
- How many drives for RAID 5?
RAID 5 ensures data protection and enhances read speeds, necessitating a minimum of three disks. It is designed to withstand the failure of one disk, maintaining data integrity by rebuilding the lost information using parity data distributed among the surviving disks.
- Is RAID 5 still being used?
It remains a popular choice for many organizations and individuals due to its effective balance between storage efficiency, fault tolerance, and performance. RAID 5 allows for one drive's worth of storage to be used for parity data, providing data protection against the failure of a single drive. This setup makes it a cost-effective solution for servers and NAS (Network Attached Storage) systems where data integrity and uptime are important, but the absolute highest levels of performance and redundancy may not be necessary.