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You should understand which limits exist for each of them so that you understand while one pool might be fine, another pool(s) could run out of storage and just monitoring at the system level is not appropriate if you have two or more pools. 

Figure 8-15 shows how to interpret the capacity and savings in a storage environment. 

<img src='content_image/1001120.jpg'>

The following metrics can be added to capacity charts for storage systems within capacity planning. Use the charts to detect capacity shortages and space usage trends. 

Alphabetical lists of the capacity and space usage metrics that you can add to charts are provided in the following sections: 

## 8.3.1 Storage system capacity metrics 

GLYPH<SM590000> Storage system capacity metrics 

GLYPH<SM590000> Pool capacity metrics 

GLYPH<SM590000> Volume capacity metrics 

The following are the system capacity metrics. 

## Allocated Space (GiB) 

The amount of space that is allocated to the regular and thin-provisioned volumes in the pools. If the pool is a parent pool, the amount of space that is allocated to the volumes in the child pools is also included. 

The space that is allocated for thin-provisioned volumes is less than their virtual capacity, which is shown in the Total Volume Capacity (GiB)  column. If a pool doesn’t have thin-provisioned volumes, the value for allocated space is the same as the value for total volume capacity. 

