Creating a vault mirror

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Before you begin

CAUTION:
The individual vaults can differ in settings (such as IDA and SecureSlice). The mirror displays data that is stored in both underlying vaults with two caveats:
  • Usable Capacity is limited to the size of the smaller vault.
  • Used Capacity is reported as the greater used capacity of the vaults.

It is highly recommended that the storage pools are equal usable capacity, as any "extra" capacity in one or the other storage pools is unusable by the vault mirror.

Attention: Vault mirrors cannot be created if the system has reached the vault limit.

If you want to create a protected mirror, see Creating a protected vault mirror.

Procedure

  1. Navigate to the Configure tab.
  2. Click Create Mirror under the Summary heading.
    The Create Mirror page appears.
  3. Enter a name for the vault mirror in the Name field.
  4. Enter an optional description in the Description field.
  5. Select from one of the three Mirror Write Configurations: Asynchronous, Synchronous, or Hard Synchronous:
    Asynchronous

    (Writes and Synchronous Deletes)

    A write response is returned once either vault has confirmed the write was successful. A delete response is returned once both vaults have responded, only one vault needs to confirm the delete was successful.

    Synchronous

    (Writes and Deletes)

    A response is returned once both vaults have responded, only one vault needs to confirm the operation was successful. This means the mirror can handle one vault being inaccessible and hence is more tolerant to outages.

    Hard Synchronous

    (Writes and Deletes)

    A response is returned once both vaults have responded, both vaults need to confirm the operation was successful. This means the mirror cannot handle any vaults being inaccessible and hence is not tolerant to outages.

  6. If a vault exists that should serve as the first vault in the vault mirror, select that vault from the Vault drop-down menu.

    There are two primary use cases associated with seeding a vault mirror with an existing vault:

    • Migrate an existing vault to be part of a persistent vault mirror. This workflow uses the vault mirror synchronization capability to migrate from a single vault to a vault mirror.
    • Migrate existing vaults to a new vault. This workflow uses the vault mirror synchronization capability to migrate data. The vault mirror is temporary and is deleted after the data is migrated to the new vault.
      CAUTION:
      To make this transition transparent to the client, a short outage is needed.
      CAUTION:

      When seeding a mirror, it is possible that writing data from one vault to the other can take precedence over the background mirror scanning process, which may result in unwanted "Mirror synchronization has not made progress" alerts. If you intend to seed a large amount of data into a mirror, contact IBM Support to so we can ensure that you avoid these warnings.

      CAUTION:
      While it is always possible that both sides of a mirror are not in sync, the risk is even higher when seeding a mirror and may result in potential data loss or inconsistency. Contact IBM Support if you are seeding a large amount of data into a mirror.
    In both use cases, perform the following steps:
    1. Rename the existing vault to something new.
    2. Create a vault mirror with the existing vaults original name.
    3. Create second vault.
    4. Perform an I/O operation on the vault mirror to initialize the synchronization.
    With the second use case, also perform the following steps:
    1. Allow the synchronization process to complete.
    2. Delete the vault mirror.
    3. Delete the original vault.
    4. Rename the new vault with the original vaults name.
  7. Click Save to create the vault mirror.
    The Mirror:<Mirror Name> page displays with an alert that indicates:
    Mirror creation successful
  8. If an existing vault was used as the basis of a mirror, skip to Step 9, otherwise follow these steps:
    1. Click Create Vault 1 to add the first vault to the vault mirror.
      The Create New Standard Vault page displays.
    2. Click Continue to begin creating the vault.
    3. Follow the steps in Creating vaults to create the standard vault.

      When the width of the pool for this vault is 3 - 6, you can also choose to enable Extended Availability for a mirror with Concentrated Dispersal vaults. Enable Extended Availability to ensure that you can read and write to the mirror if a Slicestor device outage occurs on one side and the other side is unavailable. However, this reduces usable capacity.

      The Mirror:<Mirror Name> page displays.
  9. Click Create Vault 2 to add the second vault to the vault mirror.
    The Create New Standard Vault page displays.
  10. Click Continue to begin creating the vault.
  11. Follow the steps in Creating vaults to create the standard vault.

    When the width of the pool for this vault is 3 - 6, you can also choose to enable Extended Availability for a mirror with Concentrated Dispersal vaults. Enable Extended Availability to ensure that you can read and write to the mirror if a Slicestor device outage occurs on one side and the other side is unavailable. However, this reduces usable capacity.

    The vault mirror is now complete.