How to use your laptop’s combination USB/eSATA port to temporarily run another operating system

If you're lucky enough to have a laptop with a combined eSATA/USB port, aka eSATAp, then this $19.95 cable from Amazon might be of interest to you. Especially if you temporarily wish to try another operating systems on your laptop, without affecting the primary operating system in any way.

So here's the scoop. USB 2.0 provides the power.  SATA II (3Gbps) provides the data channel. That's what eSATAp is, also known as:

• Power over eSATA
• Power eSATA
• eSATA/USB Combo
• eSATA USB Hybrid Port (EUHP)

Your laptop "thinks" it's an internal drive, and it works at the full SATA2 speed, with red LEDs on the cable indicating power. In my experience with cloning a variety of drives (using Acronis, Ghost, etc. for migrations to SSD for example), using SATA2 is generally roughly 1.25X faster than the same drive attached via a USB 3.0 to SATA adapter. Only the newest SATA3 (6Gbps) SSDs will be held back a bit by the SATA2 limitation, but nobody seems to have SATA3 eSATA ports, nor do SATA3 eSATAp cables seem to exist. All eSATA/USB combo ports may already be on the decline in popularity unfortunately, given Lenovo seems to be dropping the eSATAp themselves. One example is the move from 2011's Lenovo W520 model (mine) to 2012's W530 model. There is a potential workaround listed here, but I doubt that'd be available as easily available as a bootable operating system installation drive.

Why does OS boot compatibility matter? Well, here's a good example. I attended a recent Windows Server 2012 Loadfest event at a beautiful Microsoft facility in Cambridge, MA last Saturday. Just $45 for an all-day event. When getting ready, I faced a problem. How to use my laptop for a non-destructive, entirely temporary install of a server operating system? My tZilla laptop, fully described here, has an mSATA drive that isn't particularly easy to remove.

So here was my solution, good for intermediate or advanced computer users who wish to avoid messing with their primary operating system's boot manager/boot.ini entirely. It's always your responsibility to have a full system image backup first.

Ok, so you've been warned. Now here's the straight-forward steps:

Temporarily change to another boot drive (Setup)

Written with a Lenovo ThinkPad W520 in mind. The same concepts should apply when working with other brands, as long as it's also equipped with eSATAp.

1. Attach an available 2.5" hard drive (SSD would work too) to the eSATAp cable
2. Attach the eSATAp cable to the powered-off Lenovo W520 laptop
3. Attach external DVD reader to a USB 2.0 port, with Windows 2012 Server Evaluation DVD inserted
4. Power up, pressing F1 at the "Lenovo" logo'd boot screen, taking car to not touch the cabling, or the exposed, live circuitry on the drive
5. Leaving my system in Legacy BIOS (not UEFI BIOS), I then changed the boot order, so that the DVD drive was at the top of the list, and the eSATA drive next, making sure the mSATA drive was further down the list
6. Press F10 to Exit and Save Changes (to the BIOS)
   Alternatively, I could have disabled the mSATA port temporarily in the BIOS, preventing any chance of my Windows 8 C: drive getting messed up in any way
7. Power up, install Windows Server 2012 to the eSATAp attached 2.5" temporary drive, perform the hands-on lab exercise
8. When the temporary OS testing testing was done, shutdown

Change back again, to your original boot device (Revert to normal)

1. Ensure power is still off
2. Detach all external drives and USB keys
3. Power up, pressing F1 at the "Lenvo" logo'd boot screen
4. Change boot order (and be sure mSATA interface re-enabled), to ensure Windows 8 C: drive is back at the top of the list
5. Press F10 to Exit and Save Changes (to the BIOS)
6. Windows 8 comes right back up, untainted, untouched, no boot sectors or boot.ini edits made, just as clean as it was before the whole exercise

Below you'll find a detailed video of the changing of the BIOS settings:

Dec. 08, 2012 Update:
There is a $5.47 cable from Monoprice here that may offer similar or identical functionality, but doesn't list if it's SATA1 or SATA2. So it's not known-good, not sure it'd work identically. But the description offers this appropriate warning:

Warning! Because the drive is not enclosed, the circuit board is exposed and can be easily shorted out if you allow it to come into contact with a conducting surface or object. DO NOT place the drive on a metal surface or allow metal objects (such as screws) to come into contact with the circuit board. It is best to place the drive circuit board side down on top of a nonconducting surface. The box for this converter cable serves as an excellent surface on which to place the drive.

Nov. 05, 2013 Update:
It would appear that folks in the UK searching for an equivalent cable might want to try the eSATA-Kabel. I haven't tested it myself, however.

It would appear that folks who don't have eSATAp, but do have eSATA, might want to try this ESATAUSBMM3 cable out, which borrows a nearby USB port for the needed power. I haven't tested it myself, however.