RAID, which stands for Redundant Array of Independent Disks, also referred to as Redundant Array of Inexpensive Disks - is a technology that employs the simultaneous use of two or more hard disk drives to achieve greater levels of performance and reliability while catering to large sizes of data volume.

RAID, which stands for Redundant Array of Independent Disks, also referred to as Redundant Array of Inexpensive Disks - is a technology that employs the simultaneous use of two or more hard disk drives to achieve greater levels of performance and reliability while catering to large sizes of data volume.

 

RAID 5 arrays are used by many companies because they are cost-effective and provide a high level of fault tolerance and protection against drive failure. However, companies should be aware that RAID 5 servers can and do fail:

 

RAID 5 servers are very likely to fail when it experiences two or more disk failures.

When a RAID 5 server fails, all data will be lost. This makes it not a good alternative for data back-up as it cannot prevent data loss during a server crash. In short, RAID 5 can survive only one disk failure at any given time.

 

Data stored in these drives may still become damaged or destroyed - even when the drives are intact,

This may occur due to system malfunctions that result in part of the data being overwritten, damaged files or user errors, such as deletion of critical files, that may go unnoticed for several days or weeks.

 

RAID 5 servers also suffer the issue of correlated failures – when one disk fails, there is a high chance that the second disk will fail as well.

The theory behind the error corrections in RAID assumes that failures of drives are independent. In practice however, the drives are often of the same age with similar wear. This means the failures of these drives are statistically correlated and the chances of there being a second failure after the first failure are significantly higher.

 

Corrupted data, degraded RAID 5, deleted files, missing partitions and RAID 5 controller failure.

Apart from disk failures, RAID 5 servers may also experience failures in other ways, such as corrupted data, degraded RAID 5, deleted files, missing partitions and RAID 5 controller failure.

 

So what do you if your Raid 5 system crashes?

 

1. Your first step is to identify whether the crash is due to one disk failure or multiple disk failures.
For a situation involving one disk failure, the RAID server is running at a degraded mode. Critical data should be copied out as soon as possible before any rebuild attempt is performed. Once the critical data is copied out, standard rebuild process can then be carried out.

 

In the event that the RAID server is used as an application and data server, it may not be sufficient to recover just the data as re-configuration of application may not be possible.

 

a) In the case of single disk failure, data should still be intact. It is a normal practice to rebuild the degraded RAID volume.

However, it is advised that one should back up the disk image from all working disks before the rebuild is performed. This is because the rebuild process is rather IO intensive and there is a good likelihood that another disk may fail during the process. To do this, I suggest you may follow the emergency guide for RAID Server data recovery <hotlink to http://www.adrc.com/raid_emergency_measures.html>  to backup the disk images of all working disks. The tools are free and will save your life even if the rebuild fails.

 

b) In the event that the crash is due to multiple disks failure, system crashes, power surge, lost of RAID configuration settings, or any other unknown reason; you may need to seek assistance from a qualified RAID data recovery service provider.

Before sending in for recovery, you may want to back up the disk image of all working disks. If the RAID volume is no longer accessible, do not attempt an rebuild as it may worsen the situation.

 

To prevent losses in the event of a server crash, businesses can consider hedging their risks with a data recovery insurance plan such as the ServerInsure 10x offered by Adroit Data Recovery Centre (ADRC).

 

 

ServerInsure

 

ServerInsure is a service that allows businesses to customise their data recovery plan so they can determine how best to protect their most precious information.  ServerInsure functions like a flexible insurance plan for companies to protect their servers against crashes within their budget constraints.  Companies simply pay an annual subscription amount and they will receive extra coverage for data recovery.

 

The coverage applies to all servers covered under the plan and guarantees return of dollar value. Most importantly, it ensures that critical data is quickly recovered with minimum interruption and inconvenience.

 

Please speak to Adroit Data Recovery Centre (ADRC) consultants for estimated pricing range based on RAID configuration and circumstances and recovery process. 

 

Adroit Data Recovery Centre is able to offer ServerInsure 10x at such low cost with much shortened turnaround time as it owns the first “class 100” clean lab in Singapore, and have developed proprieta