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.
| Configuration: | Maximum capacity | Recommended RG size |
| Target maximum RG size: | 14 | 10 |
| RAID type: | RAID 4 | RAID 4 |
| Total number of drives: | 28 | 28 |
| Number of hot spares: | 2 | 2 |
| Total number of drives per aggr.: | 26 | 26 |
| Number of RAID groups per aggr.: | 2 | 3 |
| RAID group configuration: | 2 x 13(12D+1P) | 1 x 8(7D+1P); 2 x 9(8D+1P) |
| Number of data drives per aggr.: | 24 | 23 |
| Number of parity drives per aggr.: | 2 | 3 |
| Fault tolerance (disk drives per RAID group): | 1 | 1 |
| Drive model: | 800 GB SSD | 800 GB SSD |
| Right-sized drive capacity (GiB): | 744 | 744 |
| Total aggregate space (GiB): | 17856 | 17112 |
| Usable aggregate space (GiB): | 16963.200 | 16256.400 |
| Total FlexVol space (GiB): | 16115.040 | 15443.580 |
| Usable FlexVol space (GiB): | 12892.032 | 12354.864 |
How to Use
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.
Note:
This tool does not take into account Maximum Aggregate Size parameter which varies between controller
models and ONTAP versions. Maximum Aggregate Size (64-bit) can be in the range between 120 TB and 400 TB.
A similar tool, computing usable capacity based on the given aggregate configuration and disk size is also available.
For GB vs GiB comparison see the Gigabyte (GB) to Gibibyte (GiB) converter.
Recommended RAID Group Sizes
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]
RAID group sizes for RAID-TEC:
| Drive Type | Min | Default | Max | Recommended |
| SATA / MSATA / NL-SAS | 7 | 21 | 29 | 19-23 |
| SAS | 7 | 24 | 29 | 22-26 |
| SSD | 7 | 25 | 29 | 23-27 |
RAID group sizes for RAID-DP:
| Drive Type | Min | Default | Max | Recommended |
| SATA / MSATA / NL-SAS (< 6TB) | 3 | 14 | 20 | 12-16 |
| SATA / MSATA / NL-SAS (6TB, 8TB) | 3 | 14 | 14 | 12-14 |
| SAS | 3 | 16 | 28 | 14-20 |
| SSD | 3 | 24 | 28 | 20-28 |
RAID group sizes for RAID-4:
| Drive Type | Min | Default | Max | Recommended |
| SATA / NL-SAS | 2 | 7 | 7 | 5-7 |
| SAS / SSD | 2 | 8 | 14 | 6-10 |
Information source:
[1] Storage Subsystem Configuration Guide