We’ve all been suckered into buying form over function throughout our lives.  Once again it’s happened to me.  I saw the Seagate FreeAgent Pro with all of its purported features and its sexy enclosure and I decided I should have one.  I wanted a big drive with eSATA connectivity because I’m always moving my 30-60GB SharePoint virtual machines all over the place.  Watching Vista copy files is a real drag, so shaving off 20 minutes here and there would be of tremendous value. 

Immediately after receiving the drive from NewEgg, I hooked it up.  Plugging it in yielded no response from my Vista box.  I guess I expected it to work much like an external USB drive.  I know that from the computer’s perspective it doesn’t know the eSATA drive from an internal one, so I didn’t expect it to show up in the “Safely Remove Hardware” list, but I figured it would at least be recognized.  Unfortunately from a technology perspective, eSATA has not yet matured.  To get the drive to be recognized, I had to boot with the drive on.  This is not very handy, but at least it works.  You have to be care not to lose data too.  You can’t just unplug it after copying files as most frequently the operating system will still have part of the files your were writing stuck in a buffer and not yet committed to the disk.  In contrast to the USB and Firewire external busses, there is no way to tell the OS to go ahead and finish up that task so you can unplug it.  The OS will do it at its own lazy schedule.  So don’t count on it working right. You’ll have to power down the box in order to remove the drive safely.  While I was able to use device manager to disable the device and coerce the system to flush its cache, at least on one occasion my entire computer locked-up tight.  Clearly this isn’t how it’s supposed to work.  The “eject” feature known to Mac users is simply missing in Windows.  UPDATE: Server 2008 R2 fixes the eject problem as long as you install with the AHCI option configured in your BIOS.  You'll get the option to eject all SATA drives regardless of whether or not they are external.

To work best, eSATA requires a technology called “hot plugging”.  As it turns out, Microsoft doesn’t think eSATA is ready yet (even though most high-end motherboards and southbridge chipsets have supported it for years).  They don’t load the driver by default.  Curiously in Vista and Windows 7, as it turns out, the driver is installed, just not loaded.  Maybe Microsoft is hoping that by dragging their feet on eSATA, USB 3.0 will become more entrenched when it becomes available.

To enable hot plugging you have to turn it on in your computer’s BIOS.  There are typically three settings: Emulate IDE (or simply IDE), AHCI, and RAID.  Most computer’s default to emulate IDE even with SATA drives installed.  I’m not certain why, but my guess is that Windows support wasn’t ready yet when SATA drives were becoming more prevalent.  Both AHCI and RAID are modern enough to support the hot plugging feature of SATA drives.  AHCI is an acronym for Advanced Host Controller Interface.   You would select AHCI unless you plan to use the redundancy or striping features of RAID (RAID can improve performance, reliability, or both by using drive redundancy).  For most applications, AHCI is the correct choice.  One caveat, if you enable the feature in the BIOS after installing Windows, you’ll encounter the infamous BSOD (blue screen of death).  That’s because as I said earlier, the right drivers won’t load and Windows is too obstinate to just recover from the mishap and load the more appropriate drivers.  Read on to learn the trick to remedy this problem  

My initial experience with the drive was horrible.  I’ve learned a few “tricks” to get the best performance and overall experience in Vista.  Don’t expect an “advanced” section in the manual to tell you what you need to know.  You can toss that little booklet into the trash.  For those inclined to get eSATA going on their machines, the online forums are their source for knowledge.  While there are a lot of people out there giving the wrong advice, there are at least a few who know the real deal.  Some of the wrong things you’ll be told: “You have to reinstall the OS”, “You need to repair the OS installation”, “You need to buy another eSATA card”, “eSATA is not supported in Vista”.  Shockingly some of those suggestions came from Seagate’s own technical support.

I stumbled across the answer after hours of frustration and disbelief.  “Surely the eggheads at Microsoft wouldn’t be this stupid”, I thought as I searched the TechNet knowledge base.  I finally found a partial answer in this article: http://support.microsoft.com/kb/922976.   I performed the reg hack described in that article and also enabled AHCI in my BIOS.  After booting I plugged in the drive and magically the drivers loaded and the drive was recognized.   The system still doesn’t know this drive is “removable” so I still have to figure out a way to safely remove the drive.  It does appear now that when I use the soft switch on the drive enclosure that it *might* be flushing the cache first.  I presume the AHCI protocols support the drive alerting the OS that is is about to be ejected.  If this is not the case, then I need to figure out a way to set the “removal policy” of the drive to support safe removal.  Hopefully I will find a third-party tool to allow this.

In terms of performance, I had been using the new Firewire 800 (1394b) on my Macbook Pro, so I knew that even doubling the bandwidth of USB 2.0 would be a significant improvement.  Still my expectations for eSATA were far better.  Here is the general breakdown on theoretical performance based on the specifications of each bus:

To get a general vibe for performance, I copied the Windows 7 ISO (3,387,011,072 bytes) onto my Western Digital 10,000 RPM Velociraptor, which should yield a transfer time close to the read time of the Seagate since it is the bottleneck device.  It took exactly 1 minutes and 7 seconds.  My initial assessment is that the drive is getting nowhere near the 3.0 GBits/sec that it should.  It seems that it is getting 50MB/sec which is closer to the 1394a (Firewire) specification.  What a disappointment after all of that effort.

Later I’m going to try some real benchmarks and see if there is a way to safely remove the device.  I also have some other drives to try.  I want to test them using all of the various interfaces (USB 2.0, 1394a, 1394b, eSATA, mounted internally to see if wire length has anything to do with it). 

So far no joy :(