RAID controller failure

RAID can be created by software means like Linux md-RAID and LVM technologies or by using a standalone hardware component – a RAID controller. Both software and hardware RAIDs can fail leaving you with a bunch of disks and terabytes of data lost.

A hardware RAID may fail either due to a disk problem and associated with it rebuild or due to a controller failure when the RAID stops detecting by the PC at start. An usual situation is the simultaneous failure of these two RAID parts.

What to do if the PC stops detecting the RAID controller and virtual disks at the start? The obvious answer is to replace the failed controller with a new one. As ever, theory is fine, but practice is much more complicated. Often, RAID array metadata is tied to a particular controller; that’s why the new controller may not be detected by a PC, or the controller may refuse to work with the original disks. The worst situation is when replacing a controller initiates a RAID rebuild; in this case, most likely you lose all the data.

The most correct way in case of a RAID controller failure is:

1. Recover RAID array configuration using special software.
2. Copy the recovered data to a safe location (you can use, say an external drive(s) or other RAID/NAS if you have it).
3. Replace the failed controller with a new one.
4. Configure a new RAID array and copy the data back.

How to recover RAID configuration in case of a RAID controller failure

1. Remove all the disks from the failed controller and connect them to a PC separately. It is recommended to connect hard disks directly to a PC motherboard using SATA ports.
2. Download, install, and launch ReclaiMe Free RAID Recovery.
3. Select all the RAID member disks and click Start RAID0, or Start RAID5, or select other RAID type.

4. Wait till the software detects RAID configuration parameters - note that it may take a long time.
5. Once the RAID configuration is restored, you can:
   • Run ReclaiMe File Recovery to recover data. You can recover all your data using this software.
   • Save layout to the XML file. Using this option, you can save the parameters of the RAID configuration.
   • Use with other data recovery software. Provides step-by-step instructions on how to transfer the recovered parameters to certain well-known data recovery tools. Note that the instructions are created for each particular case of RAID and you should follow them exactly.

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