Capacity design method (1)-1 : Logical capacity from physical capacity (for HPEC 4D+1P) (Bare metal)

Virtual Storage Platform One SDS Block Storage Administrator Guide

Version

1.17.x

Audience

anonymous

Part Number

MK-24VSP1SDS002-04

The following is assumed:

Each storage node (or drive) in the storage cluster has the same valid physical capacity.
The storage cluster does not have faulty storage nodes or faulty drives.
The configuration, the capacity of each storage node, and the number of drives meet the system requirements.

For details about storage node requirements, see Storage node requirements in the VSP One SDS Block Setup and Configuration Guide for the model that you are using.

The following example procedure assumes that the configuration consists of five storage nodes and each storage node has a capacity of 16 TB (1.6-TB drive × 10) with the rebuild capacity policy set to "Fixed" and the tolerable number of drive failures set to 1.

The following formula is an approximate expression and there might be a margin of error of up to 1 GiB.

Convert the unit for drive capacity to TiB:
```
1.6 × 1000⁴ / 1024⁴ = 1.4552[TiB]
```

Calculate the valid physical capacity per drive (1.6 TB) by using the expression in section Capacity design principles (1) : Physical capacity (for HPEC 4D+1P) (Bare metal) .

floor((1.4552 × 1024² × 512/(512+8)) - 2048[MiB] - 124110[MiB], 124110[MiB])
    = 1365210 [MiB/device]
    floor(value, reference value)
        : The value is rounded off to a multiple close to the reference
          value.

Calculate the valid physical capacity per storage node.
```
1365210 × 10 = 13652100[MiB/Node]
```
Calculate the physical capacity used as logical capacity of the storage cluster by using the expression shown in Capacity design principles (2) : Logical capacity (for HPEC 4D+1P) (Bare metal) .
```
RoundDown((13652100 - 620550 - 1365210) / 620550)× 620550 = 11169900[MiB]
       RoundDown(numerical value)
        : A numerical value is rounded down to an integer.
```
Calculate the logical capacity of the storage cluster by using the expression shown in Capacity design principles (2) : Logical capacity (for HPEC 4D+1P) (Bare metal) .
```
(11169900 / 620550 × 496440 - 4200) × 5 = 44658600[MiB/Cluster]
```