When swapping chassis, hard drives, or adding new shelves to an active Data Domain system you may encounter a Foreign Disk error.

A disk in Foreign state in a Data Domain head unit or expansion shelf indicates that the disk contains a valid Data Domain file system data and is intended to alert to the presence of this data to make sure it is attended properly.

These instructions apply to all Data Domain systems and software releases. Use this guide at your own risk. SPS Pros is not responsible for faults, failures, data loss, etc. as a result of following this guide.

Resolving Data Domain Foreign Drive Errors

  1. ContentConfirm the disk is reporting as Foreign by identifying the disk state.
  2. If drives are Foreign after a chassis swap, DO NOT run disk unfail on any of the disks as this can cause data loss. The Foreign state is normal after a chassis swap where the head swap was done in the “System Misconfigured” menu. Follow the instructions in the chassis replacement documentation by running the system headswap command. This will push down the main board serial number to the drives and allow them to be used by the system.
  3. When adding an expansion shelf to a system that was previously attached to a different Data Domain system, the drives will report a Foreign state if the enclosure was not removed properly.To add the enclosure to the new system, the drives must be in a Spare or Unknown state.
    1. Match the serial number of the enclosure to the Foreign drives. Run the command enclosure show summary to locate the enclosure serial number. Then run the command disk show raid-info and make sure the drives reporting Foreign are in the new enclosure before proceeding. If they do not correspond, DO NOT proceed with the next steps as it can result in data loss.
    2. Unfail all the drives in the enclosure one at a time to set them to a Spare state. Then run disk show raid-info to verify the drives are Spare.
    3. Add the enclosure

How to Unfail a Data Domain Disk

CAUTION: The disk unfail command will repartition the drive and any data on that drive will be irrevocably lost. Only run disk unfail if absolutely certain that whatever is on that drive is not needed. Replacing a single drive in a system may result in a /foreign/ state where it is expected to use the disk unfail command or attaching an enclosure from another system to an existing active system may require the use of disk unfail; however, this procedure should not be used during a chassis swap.

  1. Verify the disk is not defective by replacement or by validating the drive has not failed.
  2. From the command line run the following:
    disk unfail
    Where enclosure and disk are numerical values, 1.15 for example.
  3. Depending on your version of DD OS, run the command below to verify disk status:
    For: DD OS 4.x
    Run disk show raid-info (to verify the disk has become part of the spare pool). The disk should come back as status spare.
    For: DD OS 5.x
    Run disk show state (to verify the disk has become part of the spare pool). The disk should come back as status spare.

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