https://kb.fortinet.com/kb/documentLink.do?externalID=FD46446#:~:text=On%20FortiAnalyzer%2FFortiManager%20devices%20that,to%20exchanging%20the%20hard%20disk.
If a hard disk on a FortiAnalyzer unit fails, it must be replaced. On FortiAnalyzer devices that support hardware RAID, the hard disk can be replaced while the unit is still running - known as hot swapping. On FortiAnalyzer units with software RAID, the device must be shutdown prior to exchanging the hard disk.

Reference:
Using FortiAnalyzer, you can enable log fetching. This allows FortiAnalyzer to fetch the archived logs of specified devices from another FortiAnalyzer, which you can then run queries or reports on for forensic analysis.
The FortiAnalyzer device that fetches logs operates as the fetch client, and the other FortiAnalyzer device that sends logs operates as the fetch server. Log fetching can happen only between two FortiAnalyzer devices, and both of them must be running the same firmware version. A FortiAnalyzer device can perform either the fetch server or client role, and it can perform two roles at the same time with different FortiAnalyzer devices at the other end.
FortiAnalyzer_7.0_Study_Guide-Online pag. 168

When in analyzer mode, FortiAnalyzer supports event management and reporting features.
In analyzer mode, FortiAnalyzer provides full support for log analysis, event management, and reporting capabilities.
Analyzer mode is the default operating mode.
By default, FortiAnalyzer operates in analyzer mode, which allows for log analysis and reporting.
The other options are incorrect because:
In collector mode, the FortiAnalyzer primarily stores logs and forwards them to another FortiAnalyzer in analyzer mode, not the other way around.
In collector mode, most disk space is usually allocated to storage rather than analytics, as the logs are primarily stored for forwarding.

Reference:
FortiAnalyzer_7.0_Study_Guide-Online.pdf page 54: View the tasks FortiAnalyzer administrators have performed, including progress and status.