https://docs.fortinet.com/document/fortianalyzer/6.2.5/upgrade-guide/669300/checking-reports

Reference:
Logs are received and saved in a log file on the FortiAnalyzer disks. Eventually, when the log file reaches a configured size, or at a set schedule, it is rolled over by being renamed. These files (rolled or otherwise) are known as archive logs and are considered offline so they don't offer immediate analytic support. Combined, they count toward the archive quota and retention limits, and they are deleted based on the ADOM data policy. FortiAnalyzer_7.0_Study_Guide-Online page 140

FortiAnalyzer_7.0_Study_Guide-Online.pdf page 217: Threat hunting consists in proactively searching for suspicious or potentially risky network activity in your environment. The proactive approach will help administrator find any threats that might have eluded detection by the current security solutions or configurations.

Pg 70: "after you add and register a FortiGate device with the FortiAnalyzer unit, you must also ensure that the FortiGate device is configured to send logs to the FortiAnalyzer unit."
https://docs.fortinet.com/uploaded/files/4614/FortiAnalyzer-5.4.6-Administration%20Guide.pdf Pg 45: "ADOMs must be enabled to support the logging and reporting of NON-FORTIGATE devices, such as FortiCarrier, FortiClientEMS, FortiMail, FortiWeb, FortiCache, and FortiSandbox."