If you want to increase the amount of data you want to store you need to perform the following steps:

1. first make sure you have enough free space in your disks mounted to the /data path.  
   The maximum amount you can increase is equal to the total free space of /data - 15GB.
   you can see the /data storage information under the OS screen.
   
   
2. To calculate how to increase your Index set you need to understand 3 parameters that can be retrieved from the Store screen :
   1. The amount of time (in days) you are currently storing - Index Sets table (Newest Document Time - Oldest Document Time)
   2. The amount of storage you are using  - Index Sets table (size)
   3. the amount of indexes allocated  - Index Sets table (Indices count)
3.