Max log buffer size with SSD disk for Fortigate 400E

Hi, guys,

I am still quite new to Fortinet device, and we are using Fortigate 400e HA with FortiOS V6.4.2.

https://docs.fortinet.com/document/fortigate/latest/administration-guide/574979/log-buffer-on-fortigates-with-an-ssd-disk

Document states Log buffer can be configured for temp event log storage, so some questions for me:

1. What is the max log buffer size I can configure ( for example, Forti400e ), with min. consumption of device resource (min. impact to the device).

2. If no FortiAnalyzer & FortiManager ( no any external log devices ), can I configure the "log buffer" for local reports ( as the Forti100D )

Many thanks in advance.