when using the UI or the CLI command
dfm host set <IP address> hostLogin=<username> hostPassword=<password>
is the password being reset on the filer?
No. This command only saves the credentials in the OnCommand database so we can execute APIs or commands on the storage system.
This command is used to set login and password from CLI (for each managed host that you want to run commands on). The other way is to use the Edit Settings link in the Operations Manager.
This information is for only DFM. Using these information, DFM get more information from filers for operation manager and other purpose.