Advantages and Disadvantages of RAID Levels

Summary – This blog highlights the advantages and disadvantages of RAID Levels. How different RAID levels help increase data availability by use of multiple hard disks, which further improves performance. It also suggests RAID Recovery solution in case of RAID server failure.

If you want to buy a RAID server for your business, then, you need to know the several RAID Levels. The reason being, there are several RAID Level, which may leave you confused. To set you at ease, let’s look at the RAID and its various levels that have gained popularity, and also touch upon RAID corruption and RAID data recovery. There is a brief of advantages and disadvantages of RAID Levels.

What is RAID?

Redundant Array of Independent Disks or RAID is a data storage virtualization technology in which multiple hard disks are combined together to form one or more logical unit. The performance is improved in such a way that if one disk fails, the redundant ones make up for the failed disk by making the data available.

Data is distributed in several ways across the disks and are referred to RAID levels such as RAID 0, RAID 1, RAID 2, RAID 3, RAID 4, RAID 5, RAID 6 and RAID 10, etc. Each RAID levels provides a different balance among the key RAID goals that are availability, reliability, capacity, and performance. RAID levels other than RAID 0 provide protection from unrecoverable sector read errors and from failures of entire physical drives.

Advantages and Disadvantages of Raid Levels

There are different RAID Levels and below is a brief of the advantages and disadvantages of RAID Levels.

1. RAID 0 –  Striping

RAID 0 uses striping and there is no use of disk mirroring or parity disk.RAID 0 – Striping

Due to striping, the data in RAID Level 0 is split equally into blocks that get written across all the disks in the array. Here, the storage capacity is the sum of the capacities of all the disks in the array same as with a spanned volume. By using at least 2 disks simultaneously, it offers superior input-output performance. This performance can be enhanced further by using multiple controllers; ideally,  one controller per disk.

There is no added redundancy or fault tolerance for handling disk failures, same as with a spanned volume. Thus, failure of one disk causes complete data loss and considerably reduces the possibility of Raid data recovery in comparison to a broken spanned volume. It is ideal for non-critical storage of data that have to be read or written at high speed such as on a video editing station or image retouching.

Advantages and Disadvantages of RAID 0

Advantages

Disadvantages

Good performance in both read and write operationsIt is not fault-tolerant. (If one drive fails then all data lost from RAID 0 Array)
Complete storage capacity is used. Here, overhead is not because of parity controlsNot used for mission critical systems
Easy-to-implement technology

2. RAID 1Mirroring

RAID Level 1 uses mirroring with no parity, striping, or spanning of disk space across multiple disks.

RAID 1– Mirroring

It has an exact copy or mirror of data on two or more disks belonging to the array. This means that data is stored two times by writing it on data disk and on the mirror disk. This array is useful when read performance is important as compared to write-performance. Moreover, it will continue to operate as long as one disk is in an operational state. If a drive fails, then the controller uses either the data disk or the mirror disk for data recovery and continues operation. This RAID level 1 is ideal for critical data storage and uses at least 2 drives in a RAID array.

Advantages and Disadvantages of RAID 1

Advantages

Disadvantages

Uses simple and easy-to-understand technologyUsable data storage capacity is only half of the total drive capacity because all data is written twice
Offers excellent read and write speed which is comparable to a single driveDoes not allow the swapping of the failed drive when it is hot. This means that the failed drive can be replaced only after powering down the computer to which it is connected. So, for a server that is used by many simultaneously, this is not possible at all times.
In the case of a drive failure, data can be copied to the replacement drive thus avoiding data rebuild.

3. RAID 5 – Striping with Parity

RAID Level 5 consists of block-level striping with distributed parity among drives, It is the most common and secure level.RAID 5 – Striping with Parity

Requiring a minimum of 3 drives, it can work with up to a maximum of 16 drives. Data blocks are striped across the disks, and on one disk a parity checksum of all the block data is written. The parity data is not written on a fixed drive but is spread across all the drives. With this data, the computer can recalculate the data of other blocks. That means this type of array can withstand the failure of a drive without losing data. Although it can be achieved in the software, it is recommended to use a hardware controller. The extra cache memory is used on these controllers to improve the write performance. Combining storage with security and performance, It is ideal for file and application servers.

Advantages and Disadvantages of RAID 5

Advantages

Disadvantages

Read data transactions are fast as compared to write data transactions that are somewhat slow due to the calculation of parity.Failed drives have adverse effects on throughput
Data remains accessible even after the drive failure and during replacement of the failed hard drive because the storage controller rebuilds the data on the new drive.It has a complex technology
If one of the drives of large size in the array fails, replacing and restoring the data (or the rebuild time) may take one or more day, depending on the array load and speed of the controller. If another disk gets damaged or corrupt, your data gets lost forever.

4. RAID 6 – Striping with Double Parity

RAID Level 6 is like RAID 5 with block-level striping with two distributed parity.RAID 6 – Striping with Double Parity

This means it requires a minimum 4 drives and provides fault tolerance up to 2 failed drives. It takes hours or days to rebuild raid array. During the rebuilding of RAID 5 If any other drive also fails then all data will be lost. But in RAID 6 the raid array will survive if the 2nd drives also failed. So RAID 6 is more secure than RAID 5

Advantages and Disadvantages of RAID 6

Advantages

Disadvantages

Read data transactions are very fast. Like in RAID 5Due to double parity write data transactions are slow.
Data can be easily accessible it two drives fail. Even while the failed drives are being replaced.Drive failures have an effect on throughput.
Rebuilding Raid array takes long time because of its complex structure.

5. RAID 10 (RAID 1+0) – Mirroring and Striping

RAID Level 10 is a combination of RAID 0 and RAID 1.RAID 10 – Mirroring and Striping

That means mirroring and striping are done in one single raid array. RAID 10 is a nested or hybrid and sometimes identified as RAID 1 + 0. It provides both security and performance by mirroring and striping data into multiple drives. It requires minimum 4 drives to build RAID Level 10 or (RAID 1+ 0) system.

Advantages and Disadvantages of RAID 10

Advantages

Disadvantages

Combination of two levels makes it fast and resilient at same time.As compare to RAID 5 and RAID 6 it is expensive to have redundancy because half storage goes to mirroring.
Mirroring makes RAID 10 secure.Not used for mission critical systems

Conclusion

All RAID servers are known for increasing data availability and reliability by the data redundancy. Still, they do fail to make data unavailable for use. In such situations, you can go for RAID data recovery services by Stellar Data Recovery as it is the best bet having experienced technicians for recovering data from failed RAID servers. With the kind of expertise they have, they can do RAID data recovery even in cases of severe corruption.

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