First see System Recommendations and Requirements - Large/Medium/Small Scale Environments - Disk Space needed on site:
Also see Data Retention information:
Out of Data Retention timestamp you can removed the oldest files on folders:
And regards Historical Archive Data – 15-minute summarized data (archive15 database). Typically keep 1 year of this data. (install_path\Netflow\datafiles\ReaperArchive15 ) you can remove folders that are not being used
For example in this directory has the folder 010002000250 this represents the following Device IP Address 10.2.0.250
If this device doesn't exist more in your environment or you cannot to generate reports then you can remove this device following this step:
1) On NFA web page Administration/Enable Interfaces select the Router Address 10.2.0.250 and "Delete"
2) remove the folder 010002000250 in ReaperArchive15 directory
Note: If you have a doubts regards if the device is receiving Flow check the LastFlow with this query on NFA Console machine database:
select deviceName,name,ifDescr,from_UNIXTIME(LastFlow) from routers,interfaces where routers.id=interfaces.routerID;
Open the C:/Windows/temp/query.txt and check the "from_UNIXTIME(LastFlow)" column
Also you can remove files from \NFA\Netflow\Logs folder
How does the new Data Retention Service work?