Calculate the size needed for your extended datastore

The extended datastore must have enough space to contain the amount of data generated by the Discover appliance. The following procedure explains how you can calculate approximately how much free space you need for your extended datastore.

1. Log into the Web UI of your Discover appliance.
2. Click the System Settings icon, and then click System Health.
3. Scroll down to the Datastore section.
4. In the Store Lookback chart, note the Rate and Estimated Lookback for each metric cycle (or time period) that you want to store on the external datastore. The rate for 5-minute metrics in our example figure below is 27.85 KB/s.
   
5. Calculate the amount of required space by applying the following formula: <rate> x <lookback_time>, and then convert the value to standard units.
   1. Convert the rate from seconds to days: 27.85 * 60 (seconds) * 60 (minutes) * 24 (hours) * 30 (days) = 72187200 KB for 30 days of lookback.
   2. Convert the rate from kilobytes to megabytes: 72187200 / 1024 = 70495 MB for 30 days of lookback.
   3. Convert the rate from megabytes to gigabytes:70495 / 1024 = 68 GB for 30 days of lookback.
   To store all of the 5 minute metrics from this appliance for 30 days, you need 68 GB of free space.