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  1. How long do reallocations take?

    As all reallocations are throttled, the rate of the reallocation can be computed:

    T = (Y / (X+Y)) * U * C * R

    Table 1. Variables and their Values for Reallocation
    Variable Description

    X

    Aggregate Capacity of Existing Pool (all sets)

    Y

    Capacity of New Set

    U

    Utilization Percentage of Storage Pool before Expansion

    C

    Largest Slicestor Node’s Capacity

    R

    Reallocation Throttle Rate (MBps)

    T

    Reallocation Time
    It implies that you:
    1. Multiply the capacity per drive by the number of drives per Slicestor® Node.
    2. Multiply this result (TB per node) by the amount of Slicestor® Nodes.
    3. Divide this result (TB per pool) by 2 to get the amount of storage to be reallocated.
    4. Multiply this result (TB reallocated) by the average percentage of utilization of each Slicestor® Node.
    5. Multiply this result (TB used) by capacity size of the largest Slicestor® Node.
    6. Multiply this result (TB to reallocate) by 1 million.
    7. Divide this result (MB to reallocate) by the Throttle Level.
    8. Multiply this result (Amount of time to reallocate in seconds) by the product of seconds per minute then minutes per hour then hours per day.
    9. It gives you the total days to reallocate.

      Example 2. Reallocation Time

      Add a Device Set with 24 Slicestor 2400 appliances with 40 ├ 4 TB drives to a Device Set composed of the same number, type and configuration of Slicestor appliances throttled to 500 MBps.

      T = (Y / (X+Y)) * U * C / R

      T = ((4 TB * 40 * 24) / ((4 TB * 40 * 24) + (4 TB * 40 * 24))) * 80% * (4 TB * 40) / 20 MBps

      T = ((3,840 TB / 7,680 TB) *  80% *  160 TB) / (20 MBps)
      T = (0.5 * 80% *  160 TB) / (20 MBps)
      T = (64 TB) / (20 MBps)
      T = (3,200,000) / (60 *  60 * 24)
      T = (3,200,000) / (86,400)
      T = 37.04

  2. Is there a maximum number of expansions supported?

    Storage Pools have no limit on how many times they can be expanded. Limit Vault Mirrors to five Device Sets for performance considerations.

  3. Do only certain types of data move?

    All types of data are treated identically for purposes of reallocation and proxying.

  4. Are certain storage types supported?

    The source or destination Slicestor® Nodes can use Zone Slice Storage, Packed Slice Storage or File Slice Storage. When a Storage Pool is expanded, the Slicestor® Nodes in the new Device Set use the same storage type as the other Slicestor® Nodes.

  5. Are only certain APIs supported?

    The SOH, CSO, and OpenStack APIs are supported.