There is a known issue with the 6.9.1 and 6.9.2 branches where the agent is scanning the external drives even when scanning external drives is disabled.
Release : 6.9.1 & 6.9.2
The logic to scan external drive (enable/disable) setting is reversed in implementation
amdmanagement.scan.external.drive=enable
Workaround for customer:
Stop AMD service
sed -i 's/amdmanagement.scan.external.drive=disable/amdmanagement.scan.external.drive=enable/g' /opt/Symantec/sdcssagent/AMD/system/AntiMalware.ini
Start AMD service
OR
DCS "Scan External Drive" option can be updated from "Management Console" with below path
Management Console -> Configs -> Default Detection Parameters -> Select tab "AV Config" -> Enable (Check) option Scan External Drive
And on client machine verify that the option is updated in the following configuration file:
vi /opt/Symantec/sdcssagent/AMD/system/AntiMalware.ini
[AMDManagement]
...
amdmanagement.scan.external.drive=enable