FYI, W520 eSATA and dock eSATA are independent :-)

[davidhbrown]

Just a FYI....

For some reason, I had presumed it would just be a pass-through, but it turns out that the eSATA port on the ThinkPad Mini Dock Plus Series 3 is completely separate and can be used simultaneously with the ThinkPad's own eSATA port. (At least on the W520; don't know how it's handled on any other ThinkPad models compatible with this dock.)

My first clue was noticing an extra port listed in the Intel Rapid Storage Technology application's Storage System View sidebar. 0=the regular 2.5" [H|S]DD bay, 1=ultrabay; 2=Mini-PCI mSATA; 3=onboard eSATA; 4=dock's eSATA.

I use a lot of external storage, so having the capacity is really nice. For example, I can leave my continuous backup drive on the dock's eSATA and put the drive with whatever video project I'm working on on the computer's eSATA. I'd been thinking I'd have to leave the backup on USB like it had been on my T61p which occasionally bogged things down. And that's not even getting into USB 3.0.

[ExcursionPSD]

Are you getting SATA III (6.0Gb/s) speeds out of the external eSATA port or the Dock eSATA port?

[davidhbrown]

Definitely not, for two reasons. One, I have only rotating-platter hard drives available to hook up to it, and their sustained speeds can't even hit their SATA II interface's speed. But more importantly, the SATA III / 6Gbps ports are the ones that hook to the internal hard drive bay and to the Ultrabay (numbered 0 and 1). Ports 2 and up are 3Gbps. Seems most appropriate for a notebook.