BIOS of this vendor "normally" takes some MB of space for saving a copy of its own image for recovery purposes without asking the customer to be allowed to do so.
It hides the occopied area by the device configuration overlay method / hardware protected area (DCO/HPA) which means the max available LBA will be reduced and at each POST the BIOS of this vendor blocks the device for further changes until power-off. Operating system access to the so hidden area is denied by the drive logic, because it seems to be out of the range of disk.
The decision, what drive will be modified, seems to depend on the order of the boot device or on the appearance in device list when the boot order is reset by some type of changes in BIOS i.e.SATA controller mode.
In the case the shrink occurs, this is caused by an erronoeus BIOS version where the downsize calculation for the large number of LBA's of a 1TB disk is in error.
The corrected version, which only occupies some MB of space, may cause problems with special formatted disks (Partition Magic, dynamic Volumes) of all sizes transferred to this boards and results in inaccessibility of the whole volume and destroyment of important data (i.e. dynamic volumes database) on the high-end of volume.
Usually 2113 sectors from the max native size are stolen.
Under some very specific mistakes (like plugging RAID array disks to the wromg controller plug) the RAID array information is wiped out and the RAID controller no longer accept the HDD as member of the array - either resulting in long time array rebuild or complete loss of data from RAID0.
Due to undocumented and therefore unknown functionality logic of this BIOS-backup feature all above described damages may also occur in situations of BIOS checksum error or when board battery voltage drops too low to keep DMI pool data
Message Edited by ernstatat on
06-10-2008 02:07 AMMessage Edited by ernstatat on
06-10-2008 02:10 AMMessage Edited by ernstatat on
08-23-2008 02:05 AM
