Estimating the required capacity of pool-VOLs with System Area in the pool of the data direct mapping attribute

If you want to expand a pool of the data direct mapping attribute, you must free up space in the pool. Make sure that the estimated capacity of free space is available before expanding the pool.

Use the following mathematical formulas to estimate the capacity of free space required in the pool:

Formula 1

Required-free-space-for-a-pool-to-be-added-of-one-external-volume-of-the-data-direct-mapping-attribute [in MB] = 
(ceil (pool-VOL-capacity [in MB] / 3,145,548) × 4 pages × 42 MB) + 
      ( ceil (pool-VOL-capacity [MB] / 42 MB) - 
      floor (pool-VOL-capacity [in MB] / 42 MB) ) × 
42 MB

Formula 2

Required-capacity-of-pool-VOL-with-system-area-in-one-pool-of-a-data-direct-mapping-attribute [in MB] = 
Total-of-calculated-values-by-the-Formula-1-for-each-volume + 
Management area (4200) [in MB] + 
42 [in MB]

The (ceil) indicates the number enclosed by brackets must be rounded up to the whole number.

The (floor) indicates the number enclosed by brackets must be rounded down to the whole number.

Note
  • One DP-VOL of the data direct mapping attribute uses the following capacities:
  • Mapped capacity uses multiples of 42 MB in the capacity of the pool volume, as well as the capacity for one page (The area of the capacity other than multiples of 42 MB).
  • Control information (168 MB is used per 3,145,548 MB)

    The pool-VOL with system area contains the one page capacity and the control information.

Parent Topic
  • Dynamic Provisioning

    Thin provisioning is an approach to managing storage that maximizes physical storage capacity. Instead of reserving a fixed amount of storage for a volume, capacity from the available physical pool is assigned when data is actually written to the storage media.