RAID 1 Recovery

RAID 1 data loss? How to prevent consequential damage

• Keep calm if your RAID 1 is offline.  It happens very often, that one of the RAID1 array hard drives fail without any notice, the redundancy is in-existent. This error pattern is not uncommon, in most cases it only gets noticed when the second hard drive failed as well. So the data on both defective hard drives varies. Because of this, we always recommend to send all hard drives of the RAID1 array..
• Avoid playing back backups onto the RAID1 Array. If there is no more data access because of logical damages, we strongly recommend to not play back the backup on the affected hard drives. If this backup proves to be incomplete or corrupt, valuable raw data will already be overwritten by it. As a consequence, the data recovery of the RAID1 system will be even more complex and incomplete.

Causes for data loss of mirrored RAID Arrays

The RAID controller failed

A defective RAID-Controller is a possible reason, when there is no more access to the data of RAID 1 arrays. The cause can be physical damages or errors in BIOS or the software. Especially firmware updates can lead to data loss. Swapping the controller with an exact model will most of the time not lead to the desired result, normally there are individual configuration parameters for each controller. Chances for a RAID 1 data recovery with this error pattern are very high.

Accidentally deleted data

If data was deleted by accident, the data of all hard drives of the RAID 1 array will be synchronously deleted as well. Under certain circumstances, deleted data of RAID1 can be recovered.

One hard drive of the RAID 1 array failed before

As mentioned before, one of the hard drives of RAID 1 systems can fail without any notice. The redundancy is lost.

Errors in the file system, corrupt updates

Errors within the file system can also lead to data loss of RAID1 arrays. Also - especially with NAS systems - firmware updates or bugs can cause problems with the mirrored array.