In-depth Insight into the Data Recovery on Nested RAIDs

In brief, nested RAIDs will combine two or more RAID configure levels, such as RAID 1+0, namely RAID 10, which will greatly improve data redundancy and server speed. But it can fail too. So this post will delve into data recovery on Nested RAIDs.

As an advanced data storage technology, redundant array of independent disks (RAID) has extensive popularity among businesses and the individuals who need to cope with a great deal of data in their daily work. When it comes to RAID levels, there are 10 standard levels, namely RAID 0 to RAID 9, which respectively stands for different configurations of a RAID array. RAIDs in different levels will have the different data write patterns, fault tolerance and space efficiency, etc. Apart from the 10 ones, there is also a kind of level – Nested RAIDs, also called hybrid RAIDs. Here we will introduce it in detail.

Nested RAIDs

Brief Introduction of Nested RAIDs

As its name suggested, nested RAIDs indicate that two or more different RAID levels get “nested” – combined within one controller. Therefore, you can achieve much more from such RAIDs than from a single RAID. Thus, the Nested RAIDs is popular for mission-critical systems. The most frequently-used nested RAIDs are RAID 1+0, or RAID 5+0. Some users may be used to eliminating the central “+” sign, resulting in RAID 10 or RAID 50. But you should never think that they are referring to “RAID ten” or “RAID fifty”.

Reasons Why Nested RAIDs Fail

Although nested RAIDs offers greatly improved data redundancy, it doesn’t mean that you will never encounter data loss. They can get failed and leading to data inaccessible due to the following reasons:

1) Media Failures:

In general, the nested RAIDs are designed with improved media failure tolerance. That is to say, they can sustain a number of hard drive failures. But if unluckily you have a nested RAID with limited failure tolerance, media failure is also one of the potential risks.

2) Controller Damage

In reality, controller damage is the most common causes for nested RAID failures. As you can imagine, a control is responsible for organizing and controlling all the internal hard drives. If it malfunctions, various problems can occur, such as parity issues, which will directly blocking data access.

3) Human Errors

Human errors, such as improper handling, mistaken file deletion or putting the data on your RAID server to the viruses, can lead to data loss in a nested RAID as well.

Hence, you should make regular data backups for your server data. It is similar to back up PST data on your PC, which will greatly simplify future PST recovery. So for instance, as long as you back up your RAID server data to the Cloud, even the RAID server gets corrupt, you still can recover them from the backups with ease.

Steps to Recover Data from Failed Nested RAIDs

When you realize the data loss on the failed nested RAIDs, what you proceed to do will affect the chance of data recovery. Here are some critical steps which you can take as reference.

1) Turn off System Right Now

First of all, you have to turn off the system immediately to prevent new data from getting written in the system. Otherwise, it is very likely that you will suffer the risk of data overwriting.

2) Never Try to Rebuild Array on Your Own

Then you should not try to rebuild the corrupted RAID array by yourself. If you’re not familiar with the RAID, you may make further damage on the RAID array and complicate the subsequent data recovery.

3) Write down the Symptoms

Moreover, when you are confronted with the damaged RAID server, you’d better take a note of any symptoms, which will be greatly important and helpful if you intend to consult professionals.

4) Seek Help from Professional Data Recovery Service

Chances are that you entirely have no idea about why your server fails and how to dispose of them. In this situation, the most appropriate method is to contact an experienced and well-proven data recovery service.

Author Introduction:

Shirley Zhang is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including corrupt sql and outlook repair software products. For more information visit

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