here is my situation.
I made a bootable USB 500 hdd (hdd and case were bought separately) with lots tools in it. such as bartpe, reset pwd tools and so on.
I use it to boot up workstations or laptop and perform troubleshoot/maintenance works, but once a while, it gets corrupted or accidentally written by workstation during boot up or infected by virus, which cause me big time to re-create the tools and copy data over to external hdd again.
so I'm looking for a solution that can enable write-protect on regular external hdd.
note: setting up permissions on hdd does not seem to work since write operation seems happen accidentally during boot up.