Data Loss from a RAID or Server: The Six Golden Rules of How to React in a Data Loss Situation
RAIDs (Redundant Array of Independent Disks) have become increasingly popular in recent years due to the demand for storage technologies with higher reliability. The advantage of a RAID is that it provides redundancy, which means the duplication of functions in order to create a failure-resistant system. Hence the theory underpinning the increased reliability of RAIDs is that independent failure of the constituent hard drives will not compromise the overall functionality of the system.
However RAIDs can and do fail; sometimes due to a loss of power, or the RAID losing its configuration for some reason. The drives are also subject to the same problems that can affect any hard drive e.g. mechanical, electrical, logical or firmware failures. Although the oft-cited advantage of a RAID system is that the system should survive the failure of one disk because of the redundancy, it is not uncommon for more than one drive to fail at once. This is probably because the drives are often the same age and have been subject to similar wear and tear both internally, through similar usage of component parts, and externally, through being in the same physical environment. Whatever the reason for a RAID failure, it is important to know how to respond in a data loss crisis.
1. Don't panic
The first rule of any data loss situation is not to panic. Panicking leads to poor decision-making and knee-jerk responses. The fact is that it is possible to fully or at least partly reconstruct the data in the majority of data loss situations as long as the correct approach is adopted.
2. Don't allow any disk checking software to run on the array, (e.g. Scandisk / Chkdsk etc)
These utilities deal with file system errors. However, some underlying hard drive problems can create file system errors as symptoms. The operating system will automatically run a utility to fix the file system errors and, in doing so, can damage or fragment previously retrievable data.
Earlier Windows operating systems offered users the choice whether to initiate these utilities, but more recent versions will run them automatically if the computer is shut down incorrectly. You can abort the utility by watching the boot process and pressing ESC to cancel it within ten seconds. The important files should then be copied to another type of media.
3. Don't change the disk order
It is extremely important not to change the disk order in the array. If the order has been changed, a professional data recovery company should be contacted. It should not be necessary to remove a disk from an array, but if a disk or disks have been removed, it is crucial that they are replaced in the same order.
4. Don't continue to run the system
The RAID BIOS may report that one or more of the constituent hard drives are faulty. This may be because of a physical problem with the hard drive or a configuration problem.
5. Don't reconfigure the array
If there is a problem with the configuration, it's crucial that the RAID is re-configured correctly. Incorrectly configuring the RAID will often make the data unrecoverable.
6. Do not attempt to rebuild the RAID
Under no circumstances attempt to rebuild the RAID. This could result in widescale data loss.
If you have any of the above problems and are unsure how to proceed, it is vital to contact a data recovery company for help. Any reputable company should be able to immediately understand the problem and offer advice and assistance.
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