Monday, 18 April 2011

Phantom drives in Disk Management

Occasionally, you can get a hard drive which is indicated Missing in Windows Disk Management. The reason for this behavior is simple: the information about the dynamic disks is replicated across all hard drives on a PC. The dynamic disks are assigned to "disk groups", and every disk in a group holds a copy of information about all the other disks in that group.

This is useful in RAID setups: should a controller or channel fail taking two or more RAID 5 members with it, the array is declared failed and cannot be mounted. Once the controller problem is resolved, the member disks are recognized back and the RAID can be brought online again.

The MBR-based (basic) disks, if removed, just disappear from the system, because these are not tracked.

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