i think you know the "storage path" => \Storage Card USB\
I think your Problem is, that you want to archive 500 tags.
If you look into the online help (System linits > perfomance feature) than you will see, that Siemens did not tell a "quantity" how many tags you can archive!
You can do following:
Save all data in STEP7 in a "datablock" (for sample DB10)
Create a recipe in WinCC flexible with this datablock (DB10).
Whith the system function "GetDataRecordFromPLC" and after then "ExportDataRecords" you can save the data to the USB stick as a "*.csv file".
I have do this and its works good.