To meet the customer's requirement for 450 TB of block storage with a 4:1 data reduction ratio, we need to calculate the effective usable capacity required and select the appropriate array configuration.
Step-by-Step Calculation:
Effective Usable Capacity Needed:
The workload requires 450 TB of logical storage.
With a 4:1 data reduction ratio, the physical storage required is:
Array Selection:
The selected array must provide at least 112.5 TB of usable capacity after accounting for overhead and RAID protection.
Let's evaluate the options:
A). FlashArray//C40R3 247 TB:
The FlashArray//C40R3 provides 247 TB of raw capacity. After accounting for overhead (typically ~20%), the usable capacity is approximately:Usable Capacity=247TB×0.8=197.6TB.
This exceeds the required 112.5 TB, making it a valid option.
B). FlashArray//C60R3 878 TB:
The FlashArray//C60R3 provides 878 TB of raw capacity, which is significantly larger than needed.
While it meets the requirement, it is not the minimum configuration.
C). FlashArray//X70R3 228 TB:
The FlashArray//X70R3 provides 228 TB of raw capacity. After overhead, the usable capacity is approximately:Usable Capacity=228TB×0.8=182.4TB.
While this also meets the requirement, it is more expensive than the C40R3.
D). FlashArray//C60R3 366 TB:
The FlashArray//C60R3 with 366 TB of raw capacity is overkill for this requirement and not cost-effective.
Recommendation:
The FlashArray//C40R3 247 TB provides the minimum required usable capacity while meeting the customer's needs.
Final Recommendation:
The correct answer is
A). FlashArray//C40R3 247 TB.
Reference: FlashArray//C Series Product Overview:
FlashArray//C Series
Details the capacity and use cases for FlashArray//C models.
Capacity Planning Guide:
Pure Storage Capacity Planning
Provides guidance on calculating usable capacity based on data reduction ratios.