What is a broken RAID?

Broken hardware RAID

A hardware RAID is implemented in hardware, either directly on the motherboard or on a separate RAID controller. The operating system sees the entire RAID as a single disk. The individual component disks are controlled by the hardware and not accessible to the operating system. For example, a RAID 0 composed of three 1-GB disks will be displayed in Windows® Disk Management (a built-in administrative tool) as a single 3-TB disk.

A hardware RAID can be broken if the controller loses the configuration information. You usually see error messages during BIOS initialization at boot time, before Windows® is started. Windows® will not detect the RAID at all.

In this case, see Example 2 in Recover hardware RAIDs.

If Disk Management still displays the RAID disk, it is not broken and can be handled like any ordinary disk. The disk status may be "Unallocated", "Unformatted", "Raw", "Unknown", etc.

In this case, see Example 1 in Recover hardware RAIDs.

Broken software RAID

A software RAID is created in Windows® Disk Management. The individual component disks are displayed in Disk Management.

Common reasons for a broken software RAID are:

• The RAID is deleted in Disk Management.
• A disk failure causes Windows® to lose the configuration.
• Windows® is upgraded or reinstalled.

When a RAID is broken, the disk areas allocated to it will be displayed in Disk Management as "Unallocated" or "Unknown". In this case, see Recover software RAID.

Spanned volumes are also configured in Disk Management and the same discussion applies.