It depends on the bios, if you can mark ports as external or not. Only very few boards support this, best download the manual and look for those before buying.
In a motherboard with a true eSATA port, does Linux actually distinguish between the eSATA port and the internal SATA ports?
I have a USB hard drive enclosure with both USB2 and eSATA connectors. Since SATA is nominally faster than USB2, I'm thinking if I can get away with installing a cheap mechanical adapter that can extend the internal SATA connector to an ad hoc eSATA port. Or do I need to upgrade to a new motherboard with a built-in eSATA port?
Aside from the physical connectors, are there any other differences, hardware or software-wise, between plain SATA and eSATA?
It depends on the bios, if you can mark ports as external or not. Only very few boards support this, best download the manual and look for those before buying.
As Kano has pointed out, largely it doesn't care.
If you've got a spare port on your motherboard, you can do a cheap mechanical connector (in fact, at my day job, I've done this...) with the only proviso on things being that unless your motherboard does hot-swap, you'll have to force a rescan of that channel's drive(s) via pushing "0 0 0" to the scan edge of the sysfs interface.I have a USB hard drive enclosure with both USB2 and eSATA connectors. Since SATA is nominally faster than USB2, I'm thinking if I can get away with installing a cheap mechanical adapter that can extend the internal SATA connector to an ad hoc eSATA port. Or do I need to upgrade to a new motherboard with a built-in eSATA port?
If you don't, the aftermarket add-in cards typically will work for you since they're almost all the same chipsets. Do a bit of research, though, as there might be a few that aren't supported still.
At least some of the eSATA adapters will do hot-plug correctly would be the only real big difference. eSATA is more of a connector/cable spec than much of anything else right at the moment. The next iteration of the spec will support powering the drives via the connector, so eventually there will be something a bit different.+Aside from the physical connectors, are there any other differences, hardware or software-wise, between plain SATA and eSATA?
Usually it is not that critical when you unmount and remove the device. New devices are automatically recognized on my systems - don't know if it has something to do with the external setting or not in the bios as Linux does not treat the hd as removeable device, Win does. All that happens is that you get a new name for it when you reattach it or put another drive to it, then sdb can become sdc.