Recovery from RAID Adapter Failure

Recovery from RAID Adapter Failure

When a RAID adapter failure occurs, you must replace the RAID adapter and then place the new RAID configuration onto the RAID adapter. For the IBM SCSI-2 Fast/Wide PCI-Bus RAID Adapter and IBM Fast/Wide Streaming Adapter/A, there are two ways to restore the RAID configuration:

If you have the most recent backup of the current RAID configuration, then perform the following steps:
1. Boot to the RAID Option Diskette.
2. Select Advanced Functions.
3. Select Restore RAID Configuration.
4. Enter the backup configuration filename and press Enter.
5. The RAID adapter saves the new configuration.
If no backup of the current RAID configuration is available, then perform one of the following steps:
- Remove the NVRAM module from the old RAID adapter and place it on the new RAID adapter. Boot the system. At the Mismatch Configuration screen, you see a prompt to choose the configuration to use. Select the NVRAM configuration.
  -OR-
- Manually configure the new RAID adapter via the Create/Delete Array menu of the RAID Option Diskette Main Menu. To do this, you must know what the configuration was when the RAID adapter failed. You can determine the configuration by reading the RAID log. In addition, understanding how the array was originally configured before the DDD failures will help you complete this step.

NOTE: Do not Initialize this logical drive.
When you have a defined hot spare and the RAID log is not available, remember that the hot spare becomes part of the array as soon as the first drive is marked defunct. The initial drive that went defunct is DDD in the configuration and is no longer part of the array. However, the hot-spare drive, until it is completely rebuilt, is marked as write only in the configuration. If the configuration is lost, then you must remember that the hot spare may or may not have completed rebuilding. Therefore, take this into account when replacing RAID adapters where the NVRAM is also corrupted, the known state of the array is uncertain, the RAID log is not available, drives are DDD, or a hot spare was defined.

Manually define the array according to your best estimate, including the original HSP drive as part of the array. You include the HSP drive because other drives were defunct besides the HSP. Therefore, the HSP has most likely taken over for the original drive.
Before booting to the configuration, pull the original HSP drive and mark it as defunct. This ensures the logical drive is running in the CRT state. This in turn eliminates problems if the HSP could not have completed rebuilding.

Note: The information above is to help guide you to make the best choices when servicing RAID problems. However, there will be times when data is not recoverable.

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