Pool capacity estimations when using capacity saving

A

Amount of user data

(total-defined-capacity-of-DRS-VOLs¹ + total-used-capacity-of-snapshot-data)² × (100% - (saving-ratio (%)³)

B

Amount of metadata

(total-defined-capacity-of-DRS-VOLs + total-used-capacity-of-snapshot-data²) × 6% + (total-defined-capacity-of-DRS-VOLs + defined-capacity-of-parent-VOLs⁴× (the-number-of-pairs + the-number-of-vClone-VOLs)) × 0.016%

C

Amount of garbage data

(total-defined-capacity-of-DRS-VOLs¹ + total-used-capacity-of-snapshot-data²) × (100% - (saving-ratio (%)³) × 7%

D

Free capacity

(A + B + C) / pool-depletion-threshold (%) - (A + B + C)

If you perform the operation while the pool is almost full, the performance might not be stable due to an increase in the load of garbage collection. Make sure that you have enough free space.

1. The defined capacity obtained by subtracting the total used capacity of child volumes from the total defined capacity of DRS-VOLs.
2. The total differential amount per parent volume.

   Use the following equations to obtain the differential amount per parent volume, and then estimate it considering the future growth rates:

   • If the snapshot data operation has been performed on the migration source: the used capacity of snapshot data on the source parent volume
   • If the snapshot data operation has not been performed on the migration source:

     capacity-of-parent-volume × write-IO-flow-rate-of-parent-and-child-volumes × period-from-creation-to deletion-of-each-snapshot-data

3. The ratio of the capacity before and after capacity saving.

   You can obtain the saving ratio (%) of the migration source pool in PLS(%) of the raidcom get pool –key software_saving command.

4. Of the total defined capacity of DRS-VOLs, the total capacity of all parent volumes to which Thin Image Advanced is applied.

   The capacity of each parent volume can be obtained in VOL_Capacity(BLK) of the raidcom get ldev command.