andrewabc said: Well in my case, I have external enclosure, and connected via 'esata' (on enclosure) to my motherboard.
So I guess it is really connected directly to sata port on motherboard in my case.
Motherboards that have ports designed for eSata use, have a way to identify them as such, so the OS can tell the difference between the internal and external ports.
In Windows for example a drive that is attached to an eSata port will be idetified as a removable drive and you will have the option to stop or eject it. If it is a regular SATA port, it won't give you those options.
Also it doesn't matter what formatting options you use when you create an ext2/3/4 partition, it's just a file system, it's the options in fstab that determine who can and can't mount and/or create directories on a partition, it's the permissions on the directories that determine who can or can't create files or subdirectories within the parent directory.
I'm not 100% sure, but I think if you install mountmanager it provides options that are relevant for that type of use or at the very least allows you to specify the mount options you want to use and whether you want regular users to be able to mount/unmount the partition. It doesn't look like the utility that shows up at 'System --> Administration --> Disk Utility' does that.
The way I handle my internal drives is to create a directory, then depending on what type of use is intended I will create a group, make that group the owner of the directory, then add the users to that group. If you want everyone to be able to access/edit these then you would change the group ownership to 'users', but I don't know if you can rely on that group always getting the same numerical ID in cases where you are re-installing or using the same external drive on multiple systems.
Later, Seeker