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. 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: The following are the system capacity metrics. 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. GLYPH<SM590000> Storage system capacity metrics GLYPH<SM590000> Pool capacity metrics GLYPH<SM590000> Volume capacity metrics 8.3.1 Storage system capacity metrics Allocated Space (GiB) Figure 8-15 Understanding capacity information 290  IBM FlashSystem 9200 and 9100 Best Practices and Performance Guidelines