Recovery Procedures for DDD Drives
This section provides you with procedures for recovering from many different DDD scenarios. Topics include:
An Overview of Drive Replacement
For the IBM SCSI-2 F/W PCI-Bus RAID Adapter and the IBM F/W Streaming RAID Adapter/A, you perform drive replacement via the RAID Configuration Utility. To begin, select Replace Drive and Rebuild Drive options under Replace/Rebuild on the RAID Configuration Main Menu. With this action, the RAID Adapter sends a start unit command to the drive. Once the drive starts successfully, the drive state changes from defunct (DDD) to either hot-spare (HSP) or offline (OFL). The drive state is HSP if an HSP has already taken over for this DDD drive. The drive state is OFL if no HSP drive was present when the drive went DDD. The logical drive will be in a critical state and a rebuild is necessary to bring this drive into the array as online (ONL). Once the rebuild completes successfully, the logical drive indicates OKY status.
Software Replace vs. Physical Replace
When the RAID Adapter communicates with the hardfile and receives an unexpected response the adapter will mark the drive defunct in order to avoid any potential data loss. For example, this could occur in the event of a power loss to any of the components in the SCSI RAID subsystem. In this case, the RAID adapter will err on the side of safety and will no longer write to that drive although the drive may not be defective in anyway.
Different circumstances warrant either a software replace or a physical replace, as discussed in the following bullets:
IF YOU USE THE WRONG ORDER WHEN YOU ATTEMPT A SOFTWARE REPLACE, DATA CORRUPTION RESULTS.
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