NetApp Usable Space Calculator 2

This calculator allows to compute and compare usable space for two NetApp FAS storage system configurations. The first configuration is aimed at achieving the maximum usable disk space for the given number of disk drives. The second configuration is aimed at keeping the number of drives per RAID group within the recommended range.

RAID type:
Drive model: 
or Right-sized capacity (GiB): 
Total number of drives: 
Number of hot spares: 
WAFL overhead (%):
Aggregate snapshot reserve (%): 
Volume snapshot reserve (%): 
Fractional reserve (%):

Configuration: Maximum capacity  Recommended RG size 
Target maximum RG size:2828
Total number of drives:2828
Number of hot spares:22
Total number of drives per aggr.: 2626
Number of RAID groups per aggr.: 11
RAID group configuration:1 x 26(24D+2P)1 x 26(24D+2P)
Number of data drives per aggr.: 2424
Number of parity drives per aggr.: 22
Fault tolerance
(disk drives per RAID group):
Drive model:800 GB SSD800 GB SSD
Right-sized drive capacity (GiB):744744
Total aggregate space (GiB):1785617856
Usable aggregate space (GiB):16070.40016070.400
Total FlexVol space (GiB):15266.88015266.880
Usable FlexVol space (GiB):12213.50412213.504


To perform calculation select one of the drives from the Drive model list. The tool will use the proper right-sized drive capacity value to perform calculations. If drive is not on the list use the Right-sized capacity field and the adjacent drive type list. If entered, the Right-sized capacity value overrides the selection from the Drive model list.
To use the Drive model list, clear the Right-sized capacity field.

This tool does not take into account Maximum Aggregate Size parameter which varies between controller models and OTAP versions. Maximum Aggregate Size (64-bit) can be in the range between 120 TB and 400 TB.

A simplified version of this tool is also available.

For GB vs GiB see Gigabyte (GB) to Gibibyte (GiB) converter.

RAID group sizes for RAID-TEC:

Drive TypeMinDefaultMaxRecommended
SATA / MSATA / NL-SAS7212919-23

RAID group sizes for RAID-DP:

Drive TypeMinDefaultMaxRecommended
SATA / MSATA / NL-SAS (< 6TB)3142012-16
SATA / MSATA / NL-SAS (6TB, 8TB)3141412-14

RAID group sizes for RAID-4:

Drive TypeMinDefaultMaxRecommended
SATA / NL-SAS2775-7
SAS / SSD28146-10

The general rule is to keep the raid group size close to the default (+ or - 2 drives/raid group). If multiple RAID group sizes achieve an even RAID group layout, NetApp recommends using the higher RAID group size value within the range. It is also preferred to achieve an even RAID group layout so that no single RAID group is deficient more than a single drive. [1]

Information source:
[1] Storage Subsystem Configuration Guide