A Tale Of Two Thunderbolt Storage Devices: Seagate's GoFlex Desk and Western Digital's Thunderbolt Duo
by Brian Dipert on May 13, 2012 7:52 PM EST- Posted in
- Thunderbolt
- Seagate
- WD
- Western Digital
My initial assumption had been that WD put a hardware RAID controller between the Thunderbolt interface and the two SATA HDDs, akin to what Promise had done with the Pegasus, and as has also been the case with any number of other dual-drive enclosures I've tested and otherwise used over the years. The fact that the Thunderbolt Duo didn't have configuration switches (an O/S-agnostic and otherwise convenient means of setting the RAID mode in hardware versus via a software utility) gave me pause, but not all hardware RAID controller-based enclosures I've used have had them.
However, after powering up the Thunderbolt Duo for the first time, I happened to fire up Mac OS X's built-in Disk Utility and received clear indication that the enclosure was (as with the LaCie Little Big Disk) instead leveraging Mac OS X's native software RAID facilities:
As previously mentioned, I promised my WD PR contact that I wouldn't take the enclosure apart. But I'm guessing that, akin to the LaCie Thunderbolt eSATA Hub that Anand saw at CES 2012, WD has built into the Thunderbolt Duo a Thunderbolt to dual SATA controller. Such a feature allows the system-side Thunderbolt controller to "see" each Thunderbolt Duo as a single bus peripheral, thereby enabling WD to accurately claim that you can daisy-chain numerous drives to each other and the system before you violate Apple's six-max specifications.
WD includes the installer for WD Drive Utilities, a status-and-configuration program, right on the Thunderbolt Duo, although I found (and downloaded, installed and used instead) an updated version of the utilities at the company's support website:
However, I found myself using Mac OS X's Disk Utility in this study instead, for several reasons (and with WD's official sanction, as it turns out). For one thing, Disk Utility offers the auto-rebuild-on-error option for RAID 1 (mirrored), a setting that isn't exposed in the WD program. Also left unexposed in the WD utility are the five block-size options (16KB, 32KB, 64KB, 128KB and 256KB) that Disk Utility supports for both RAID 0 and RAID 1; I'm assuming (but don't know for sure) that WD's program uses Mac OS X's 32KB default block size setting.
WD's program offers the "JBOD" ability to use the two HDDs as discrete drives, even optionally putting HFS+ on one and exFAT on the other, which is convenient for dual-O/S-booting purposes. However, surprisingly, the WD utility does not expose Disk Utility's 'Concatenate' option, which combines the two drives in a non-striped fashion. Although SPAN (i.e. BIG) is not an official RAID mode, it's commonly supported by RAID utilities. And curiously, although the WD utility doesn't support configuring the drives in SPAN mode, it correctly identifies a two-drive array that's already been concatenated via Disk Utility:
One historical reason (of many) for going with hardware RAID is that (versus software RAID) it didn't excessively burden the CPU, with both resultant system battery life and performance impacts. Thankfully, if my experiments are indicative of a broader conclusion, those days are over. Note that the kernel_task process reports using only around 6% of one core of the CPU during heavy use of the Thunderbolt Duo in RAID 0 mode, and that the system reports four cores (thanks to HyperThreading virtualization):
Given that kernel_task typically consumes 3-4% of a CPU core under normal operating conditions, an extra few-percent load for heavily utilized software RAID is, in my opinion, quite acceptable.
Facebook
Twitter
RSS
46 Comments
View All Comments
Death666Angel - Wednesday, May 16, 2012 - link
This sentence is a bit misleading:"a specific RPM at any particular time is dependent on both access requirements and sensed operating temperature." - This would suggest that this HDD runs with varying RPMs. This is not true. One HDD runs with one RPM. However, between the various HDDs among one charge there can be different RPM settings. So one Caviar Green "IntelliPower" runs with 5400 while the next runs with 5900. You will not see one 5400 unit suddenly run at 5900 because the temperatures are particularly low.
bdipert - Saturday, May 19, 2012 - link
Dear Death666Angel, I don't think you're correct. WD has told me on many occasions that the IntelliPower algorithm varies a drive's rotational speed over time as a function of performance demand and operating temperature. And past AnandTech writeups make similar statements:http://www.anandtech.com/show/2385/2
for example
wolfgang123usa - Thursday, July 12, 2012 - link
The real advantage of Thunderbolt should be that it carries power, but special this feature is very limited, as the power pin on the connector is very small and shall carry 10Watts, Sata connectors, USB and other have bigger contact surfaces and/or multiple pins to carry power. The display port adapter was designed for a lot less power then 10watts, that's the current issue with Thunderbolt today. Some details can be found here:http://technology.coolodman.com
When a self powered thunderbolt device is used it works fine and uses only about 22% overhead to encapsulate the PCIe bus, so the speed with fast SSD's like Samsung 830 series is really not bad.
marmot_animal - Friday, July 13, 2012 - link
Two months after this article was written, I find Thunderbolt options at the same phase, quite limited. So I bought the Seagate GoFlex Thunderbolt adapter for $$$ from B&H, plus the cable. Although expensive, it seems for the time being the least expensive approach, albeit a DIY approach, to use raw hard drives, of which I have an expanding collection for my video and audio projects.If my research is correct, there are no official generic Tbolt docks, unlike the common USB3 (and earlier interfaces) docks on Tiger Direct. Although LaCie 2big bays appear to physically allow users to swap raw hard drives, LaCie voids the warranty in doing so. Obviously LaCie discourages a DIY approach and of course favors consumers to procure LaCie's aftermarket harddrive-installed bays. This is less of a diehard obstacle as opposed to WD's Caviar requirement. Conversely, I'm not into opening up enclosures to swap drives. It requires tools, is time-consuming, and is semi-permanent. My preference is to swap raw drives on-the-fly.
At least the GoFlex DIY hacker method works, and I secure the drive on the dock via rubber band technology. I report 'so far so good' with raw drives. I don't know precise speed details as long as I'm able to put the Tbolt bus to use, and it appears faster than any other bus I've used with FCPX. Too many companies try to hijack Tbolt by instilling proprietary constraints. Nevertheless, I find the GoFlex design with its generic SATA interface to be an extremely niche approach because most consumers won't want to seat a raw hard drive somewhat precariously in a dock not designed for such use.
spanading - Saturday, October 6, 2012 - link
Honestly peps,Why are people compairing the two. Yes USB is great if you are conneting things like HHD, Mice, Tablets, and the like, but remember you only have 5Gb in a single channel, one way maximum to play with, while thunderbolt has 20Gb when using both channels. True neither USB 3 nor Thunderbolt would be maxed out by a single HDD, but when connecting several data hungry devices at once, (which with thunderbolt can include monitors, and possible legacy port hubs, if they ever arrive) then USB will show the strain a lot quicker than thunderbolt.
Hence why you need a thunderbolt port? Well if all you are doing is plugging in one HHD over it it is probably overkill, BUT, if you like to have one of those new shiny Ultra books to use on the run but then want a fully fledged PC when you get home, Thunderbolt gives you this potential, but only having to connect 1 cable, rather than 3 or 4. Plus with it being compatible with PCi then you can have expansion cards to further enhance performance with out the need for a completely separate PC. Now before you complain ultra books have low spec CPUs, go and play with one that uses a SSD and see how much speed a traditional HDD sucks up while the system waits for data. As an example, my 2011 Mac book air has a 1.7 GHz dual core i5 with integrated graphic and only 4GB of memory, and on day to day tasks, is faster than my 2011 mac min server with a 2.0Ghz Quad core i7 with the same integrated graphics but 16 GB of RAM. In fact my macbook only struggles when the RAM is all used up, which is not very often .
I guess this is exactly what Dan Neely meant. Good on you Dan, I guess the USB people have not quite grasped the fundamental difference yet.
biswa60 - Saturday, October 19, 2019 - link
Each Thunderbolt port handles 40 Gbps of aggregate bandwidth, consisting of two pairs' worth of distinct 10 Gbps transmit and receive laneshttps://theprintcalendar.com/
https://vicschoolholidays.com/