Estimating FMC capacity to expand an existing pool
When you need to install additional FMC drives to expand an existing pool, use the following workflow to estimate the required capacity.
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Estimate the pool capacity to be added.
Estimate the pool capacity required for user data in the same way you estimated capacity when creating a pool. If you are expanding a pool, also estimate the additional capacity.
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Check the Saving %.
The Saving % is displayed in the Pools window. View the Saving % by clicking .
NoteIf the 14-TB FMC is used and the Saving % confirmed in this step exceeds 75%, apply 75% for "Saving %" in the formula of the next step. -
Estimate the required FMC capacity.
Use the following formula to calculate the required FMC capacity:
Required FMC capacity = Required pool capacity × [100% - (Saving % - 10%)]
The buffer in the above formula is as follows:
- - 10%: Buffer representing expected increase in capacity because of degradation in Saving %
Estimate the additional FMC capacity to be purchased according to the required FMC capacity calculated using the above formula, and the free capacity assured for writing.
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Check the free capacity assured for writing.
In the Pools tab of the Pools window, check the value of FMC Pool Volumes Capacity. The free capacity reserved for writing is the difference between the Total and Used values.
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Estimate the additional FMC capacity to be purchased.
If the space calculated in step 4 is sufficient, this step is unnecessary. If the space is insufficient, use the following formula to calculate the required FMC capacity:
Required FMC capacity to be purchased = (Required FMC capacity - free capacity assured for writing in step 4) × 110%