RAID vs. non-RAID Storage - Difference & Comparison

RAID vs. non-RAID Storage - Difference & Comparison

There are storage technology options that you can choose to get better performance and redundancy. RAID storage is one of the options that can be considered against regular hard drives. The article tries to compare the two options and highlight some of the pros and cons of each.


RAID Storage System

RAID, an acronym for Redundant Array of Independent Disks, is a technology that allows combining several disks into a one contiguous storage. Thus, the general difference between a RAID and typical hard drive is that using a RAID you can create some really big data storage. As of now, the maximum capacity of a typical hard drive you can buy is 4 TB (Hitachi); combining disks into a RAID, you can get almost any reasonable capacity. Also, recently new technologies based on RAID have become widely available; it is about Storage Spaces and a thin provisioning feature of Windows 8.1 and Windows Server 2012 R2 that allow creating virtually unlimited data storage.

Another difference between RAID and non-RAID systems is complexity. In RAIDs, data is being placed not only according to commands of the file system driver, but also following the pattern of the particular RAID layout. More than that, there are RAID types for which there is no generally accepted standard layout pattern. For example, RAID 6 arrays created by different controllers use different block placement pattern and sometimes even compute parity differently.

On the one hand, a RAID ensures more reliability with respect to disk failure; on the other hand, RAID arrays still have a single point of failure - controller in case of a hardware RAID or managing software in a software RAID. When a controller fails, there is significant chance to lose all the data stored on the RAID. This also includes operator errors, for example wrong actions during the rebuild that nullify all reliability based on data redundancy.

If you need to place a large amount of data of an approximately similar purpose, for example backups that cannot be divided into logical groups (as it would be in case of movies and music) then stick to a RAID because it makes it easy for you to store data.


What Are Different Types Of RAID Systems?

There are many types of RAID hard drives. 

RAID 0 / Stripping - No Redundancy

RAID 0 system is simplest to implement. It just takes number of drives and combines them into an array of drives that can be accessed in parallel. 

RAID 0 Drives support high speed read and writes, however they do not support redundancy. This means if a single drive in the RAID array fails you will lose all the data. 

When Should I Use RAID 0 System?

Even though it may sound like RAID 0 is very risky to store data it can still be a good choice for storage for data that is non critical. Many systems use it for caching the data for faster read access. In such systems loss of data is not a problem since the cache data is just a copy of original data.

RAID 1 / Mirroring - Mirrored Drives for Redundancy

RAID 1 resolves the data loss problem by introducing redundancy. Each drive in RAID 1 is mirrored for redundancy. This gives more reliable storage. 

Since RAID 1 uses double the number of drives its capacity reduces to half for the same hardware. 

When Should I Use RAID 1 System?

RAID 1 system gives a good balance of reliability and speed. This can be used as a good backup drive that works at high speed.

Can I Switch Between RAID 0 and RAID 1?

Switching between RAID 0 and RAID 1 may be possible, however it will require complete drive formatting since the two approaches have different way to store data. 

Converting a RAID 0 to RAID 1 will reduce the drive capacity to half since RAID 1 requires a mirror drive for redundancy.

There are some popular RAID 0/1 products in market that you can use based on your choice of storage preference. 

RAID 5 - Stripping with Distributed Risk Parity

RAID 5 systems use 3 drives for redundancy along with distribution of parity information across multiple disks. This makes it more reliable than RAID 1 system since you can lose one disk and still not lose your data.


When Should I Use RAID 5 System?


RAID 5 has faster read access that makes it a good choice for web application data to be stored and served at a good speed. 

RAID 5 systems are also good for hosting file servers like SFTP, FTP and similar for faster retrieval of large files. 

Even though RAID 5 achieves a better risk management, it offers reduced write speeds. This makes it a poor choice for write intense systems e.g. backups



What is the Minimum number of Disks / Drives Required for RAID 5 Systems?

RAID 5 Requires Minimum 3 Drives


What is the Maximum number of Disks / Drives Possible for RAID 5 Systems?

RAID 5 Can support up to a maximum of 32 drives to be implemented

RAID 6 - Stripping with Higher Distributed Risk Parity

RAID 6 systems improve the risk parity in RAID 5 system by using 4 drives for redundancy along with distribution of parity information across multiple disks. This makes it more reliable than RAID 5 system since you can lose two disk and still not lose your data.

When Should I Use RAID 6 System?

Just like RAID 5 systems, RAID 6 systems have same advantages of faster reading that makes it suitable for web server, file servers and any general purpose read intense services. 

Just like RAID 5, RAID 6 write speed is still lower as compared with RAID 1, therefore it makes a poor choice for any write intense systems.

What is the Minimum number of Disks / Drives Required for RAID 6 Systems?


RAID 6 Requires Minimum 4 Drives

What is the Maximum number of Disks / Drives Possible for RAID 6 Systems?


RAID 6 Can support up to a maximum of 32 drives to be implemented

RAID 10 - Combination of RAID 1 and RAID 0

RAID 10 gets best of both RAID 1 and RAID 0 by combining them in one system. This gives high speed read and write operations along with good redundancy. RAID 10 requires minimum of 4 drives. 

The capacity on RAID 10 system is just like RAID 1, it reduces to half due to redundancy of drives. 

When Should I Use RAID 10 System?

RAID 10 systems are good for places where high speed read and write is required. This is generally one of the best choice since disks are not expensive. 

These systems may be larger in size so you may want to consider other alternatives if this is being used at home for personal data backup systems. 

Can I Switch Between RAID 1 and RAID 10?


As of now, not many systems offer this. I recently noticed TERRAMASTER D5-300 on amazon that offers this feature.  

Non-RAID

When talking about non-RAID storage devices, we often imagine a regular hard drive meaning that this is a system limited by capacity. As mentioned above, nowadays, this is about several terabytes and the annual increase in the hard drive capacity is far from 1 TB. Obviously, non-RAID storage loses to a RAID system in terms of capacity.

Typical hard disks have relatively slow read and write speed. Creating a RAID of several disks typically improves performance somewhat. The notable exceptions from this are tasks where many write streams are used (for example video conversion). In case of multiple simultaneous data streams, assigning each stream to a designated hard drive provides better performance than combining all drives into a RAID array. 

Also, we shouldn't forget about solid state drives (SSD). An SSD drove the final nail into coffin of a RAID0 that was for a long time considered a perfect choice to place an operating system on it for maximum performance.


RAID/non RAID Failures

Many know that a hard drive can fail due to a logical or physical issue. With a RAID, people often think they are immune to data loss because they have a RAID that is usually redundant. In practice, it is not always true since there are failures affect the RAID itself. 

For example, if you deal with a hardware RAID, one of the common failures is a controller failure when you completely lost access to the data. Another common issue is an operator error, for example, wrong actions during RAID rebuild. In both these cases, before recovering data you need to restore RAID configuration: number of disks, disk order, block size, start offset at the member disks at which user data starts, and so on. If you ever face such a problem, look at ReclaiMe Free RAID Recovery, a free utility that is capable to detect RAID parameters automatically.


Conclusion

Nowadays, it becomes clear that RAID arrays are creeping up to home users. This is most clearly seen in the recently introduced Windows 8.1 that has special features to deal with large storage devices and RAID technology. Developers greatly simplify both the process of creation of such storage and the process of adding disks if free space comes to end. However, the life of non-RAID storage devices doesn't end at this point. If capacity of a typical hard drive is enough for you, use non-RAID devices for their simplicity and mobility.

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