Monday, June 4, 2012

Mac with Seagate Thunderbolt Adapter and 512 GB SSD


Samsung 830 Series 512GB SSD
in GoFlex case 

As some Thunderbolt devices are available now and the 512 GB   SSD's are a lot cheaper then a year ago (and still expensive), I thought it is time to try Thunderbolt with external SSD, to have a fast
Seagate GoFlex portable TB Adapter
Seagate TB desktop Adapter
external bootable hard disk. As Promise and Pegasus disk arrays are very expensive and the LaCie TB Adapter is also not cheap, I decided to get a Seagate desktop Thunderbolt adapter and a Seagate GoFlex portable Thunderbolt adapter and attach a Samsung 830 Series 512GB SSD to get some real speed and the ability to boot from this external drive.








What is Thunderbolt?

If you do not know what Thunderbolt is, read here  http://en.wikipedia.org/wiki/Thunderbolt_(interface)  and www.intel.com/technology/io/thunderbolt/index.htm  and for available Thunderbolt devices you find reports on this link http://thunderboltreviews.com/ Thunderbolt is a development by Intel, and Apple supplied the mini Displayport connector to be used for Thunderbolt connections and Apple had the right to use Thunderbolt for the first year exclusively. But now the number of motherboards for PC's with Thunderbolt ports is daily increasing, and not only a Mac technology anymore, see this page for devices and PC motherboards https://thunderbolttechnology.net/news/press 

Do NOT see the Thunderbolt I/F as a replacement for USB3, it is a external extension of the PCIe Bus and Displayport, this means a PCIe chipset or card can be used in a external Thunderbolt box with full speed. As the Thunderbolt link has NO connection to USB devices or USB controller on the motherboard, you need a PCIe USB controller to offer USB2 or USB3 ports on a external Thunderbolt box. So it could replace a USB3 link (when proper implemented), but it is a lot more versatile and can be used as single cable to a docking station with multiple different ports (like the Appel Thunderbolt Display or the Belkin Thunderbolt docking station)

As usual, first the disclaimer:
  • You are fully responsible for your modifications
  • Any modifications may damage your products
  • You loose the warranty on all products, when the products are used in a way they are not intended to be used, (like adding non Seagate HD to adapter, using a SATA extension cable etc)
  • You loose the warranty when opening the devices
  • The devices loose the FCC, EMI/EMC certification when used different then intended (using a SATA extension without shielding increases the EMI/EMC)
  • My results may differ from your results
  • This description is only for educational purpose
  • I am not affiliated to any company mentioned in this blog
  • I do NOT have any insider knowledge of Thunderbolt technology, Apple or Intel
  • All trademarks mentioned in this blog are owned by their respective owners
Equipment used:
I bought:
I removed the 500GB disk drive from the GoFlex case and replaced it with the Samsung SSD and moved the original 500GB drive in the cheap USB2 case to use it as a offsite backup solution. The plan was to use the red GoFlex case with the Samsung SSD sometimes with the USB3 adapter from Seagate, or the Seagate Thunderbolt desktop adapter and when travelling with the Seagate GoFlex Thunderbolt adapter.
Samsung 830 Series 512GB SSD in GoFlex case

As with a lot of plans, it did not work as imagined, the plan needed some modifications. As I found out, after buying all the pieces, the Seagate GoFlex disks do not fit on the Seagate Thunderbolt desktop adapter, because the SATA connector on the GoFlex case is a couple of Millimeters (about 1/4") inside the case and the Desktop adapter has only a short SATA connector and so does not go deep enough in the case to make connection. Read further down about the dis-connects and the resolution of the issue with Seagate GoFlex portable Thunderbolt adapter when connected directly to MBP.

I bought:
make sure you get a short cable and you can remove the cover on the disk side SATA connector that it fits in the slot of the GoFlex disk case. The reason to use the shortest possible cable is, that most SATA extensions do not specify if they are SATA III (6GB certified), on short cables there should be no problems with 6GB transfer rates and also to limit the increase of EMI caused by long cable runs. You can shorten the power wires of the connection, but not the SATA signalling connection.

Testing:

Now the first test, connected the Samsung SSD with the SATA extension to the Seagate desktop adapter, connect the external power supply to the TB adapter and to power and then  connect the Apple TB cable to my already booted MBP. Voila ! few second later the SSD appears on the desktop. Now starting the Black Magic Speed test, select the TB-SSD, set test size to 5GB and hit the start button.


About 328 MB write and 365 MB read speed.....not bad for a external disk! Copied multiple times 41 Gb vmdk file from my W7-VM from internal OCZ SSD (slower then my new external SSD) with 225 MB speed to external SSD, a couple of times.....all works fine.

Seagate TB desktop adapter with Samsung 830 series 512GB SSD

Now the next test, standard 1.5TB GoFlex disk on the Seagate TB Desk adapter and daisy chain with 50cm Elgato TB-cable the Seagate TB-GoFlex adapter with the Samsung SSD attached.

Seagate portable TB adapter as last point in Thunderbolt daisy chain
Now the Black Magic Speed test with the Samsung SSD shows 307 MB write and 361 MB read speed. So a bit slower, but still good enough :-) then again the 41 GB vmdk file multiple times copied with 220MB speed without any issues.

TB portable in daisy chain after desktop adapter



Also the standard 1.5TB GoFlex disks works fine on the desktop adapter when used with the SATA extension, but a lot slower.

Thermal Issues with standard configuration

The Seagate TB portable GoFlex adapter get's really hot after a short time. Seems to be a bad design decision to have the hot TB adapter below the disk, as the disk will be heated up even more. With a SSD attached, you can lay the disk head down to improve the thermal situation, but when you use a standard rotational GoFlex disk you can NOT lay the disk down, as a rotational disk shall never be operated head down as the bearing will wear out fast and error correction will kick in very often when the bearing does not work proper. I tested a standard GoFlex 1.5 TB with Acronis backup and SuperFlex Synchronizer software, meaning that the copy process runs maybe multiple hours, the disk gets so hot that you almost can not touch it, this means if you do not want to reduce drastically the live time of the rotational disk you have to use a SATA extension cable that the disk does NOT touch the TB adapter and so reduce the temperature stress.
GoFlex rotational drive mounted above Seagate TB adapter, as intended by Seagate and the disk gets additional heated up by the TB adapter
And now the real troubles start with the next test:

Seagate Thunderbolt GoFlex Adapter with Samsung 512Gb SSD and Elgato cable direct connected to MBP.

Seagate portable TB adapter with Elgato TB cable direct connected to MBP-pro

The SSD is shown on the desktop after a couple of seconds, then started Black magic Speed test.....and the SSD disconnects with error message. Sometimes before first speedtest is displayed, sometimes after. When you run the test immediately after you plug in the TB-cable (when TB connectors and Seagate adapter is cold) mostly the first Speed test works, but fails all the time when MBP gets hot around TB-connector, TB-cable connectors get hot and the Seagate portable TB connector gets hot. Don't forget, also the MBP close to the TB connector gets very hot (there is a power controller for the TB port in the MBP, not only in the Seagate adapter.....but we will discuss this later)

Then test with the 41 GB vmdk file.....same result, disk disconnects after few GB with same error message.

Error with file copy with Path Finder
Error with Black Magic Speed Test
What's going on? A short Google session shows that everyone has problems with portable TB adapter from Seagate when used with SSD bigger then 240GB. for example here: http://forums.macrumors.com/showthread.php?t=1317577&highlight=thunderbolt+seagate&page=11 

When I tested the same Seagate TB portable Adapter with the Samsung 512GB SSD connected in Daisy chain with the Seagate TB desktop adapter to my MBP, all was working


fine, but now when connected directly to MBP, I get this disk disconnect problem. I suspected there is a power issue, because Samsung 830 series SSD draw a lot of power and when connected in daisy chain to Seagate desktop adapter the power for the Seagate TB portable adapter is NOT supplied from MBP, it will be supplied from the desktop adapter with own external power supply via the Elgato TB cable to the Seagate TB portable adapter.





Now the troubleshooting starts

The test bench with all equipment used for troubleshooting
SATA extension with test points
You can see in left picture the removed cover on the left SATA connector to make it slim, to fit into the GoFlex case. The brown tape on the connector and cable will protect the cable from breaking without the cover on connector.




Inserted barrier strip with test points to attach multimeter and oscilloscope from Oscium to the SATA extension cable. I connected the multimeter and Oscium and running again the Black Magic Speed test and the copy the large 41Gb vmdk file. You get following result with the oscilloscope when the external SSD disconnects, measured between black and red wire, 5VDC supplied to SSD.




Oscium 104 screen shoot, the drop of voltage to 1 VDC in the right of picture is when the SSD disconnects

On the SATA cable from the portable adapter only both black ground/0VDC wires and the red +5VDC wires are used to supply power to the SSD.

If you test the same on the desktop adapter then also the yellow wire for +12VDC is used to power 3.5" SATA disks.

You see a voltage drop from +5VDC to about +1VDC and is about 12 ms wide on the top. Keep in mind that the scope does not have full sampling rates at this speed, so it is possible that very narrow drops/peaks maybe. This voltage drops to +1VDC stops the SSD (and disconnects the SSD) and the MBP  will not get any signaling on the SATA connection and the used SW will shows the disconnect message. this can be repeated anytime when MBP, TB-cable and Seagate portable TB adapter gets hot.

Some thoughts about power over Thunderbolt connection

So whats the problem? Some investigation via Google shows that the Thunderbolt specifications from Intel are not public available, only to affiliated companies. So the only information I could gather about the power management on the thunderbolt cable is following:

On Display port, or when Display port equipment is used and power is needed, then PIN 20 on the connector carries +3.3VDC with maximum 500 mW
On Thunderbolt the power is increased and the source supplies 10Watts to Thunderbolt equipment via PIN 20 on Thunderbolt connector. I could not find any definitiv answer how high the voltage shall be. http://en.wikipedia.org/wiki/Thunderbolt_(interface) When you check the Texas Instruments Thunderbolt support chips documentation http://www.eetimes.com/electronics-products/electronic-product-reviews/analog-products/4238224/Chipset-family-supports-Thunderbolt-10-3-Gbps-interface-standard
 you can see the voltage could be between 3.3 and 18 Volt. Also it is stated that the source and also the sink side of the Thunderbolt/Display port connection can be the power source (or not) this means the support chips check wich side supplies the power, know if it is display port or TB connection etc. My assumption is that +3.3VDC is not enough to supply 10Watts of power via this tiny small single PIN 20 on the Thunderbolt connection.  It must be higher then +3.3VDC and lower then +18VDC that the support chips can handle it. But even if it is +15VDC, it would mean 0.67 Amps will flow over this small and tiny connection PIN 20......That is a lot of amperage and when there is a small patina on the contact.....it could get easy fried. You have to keep in mind, the TB-cable has the driver circuits for the cable (TX and RX) and needs power from this 10 Watts and also the TB-controller and other chips on the portable Seagate TB adapter need power, so only some part of the 10 Watt can reach the SSD or hard disk. When you read the forums, a couple of people are talking about fried TB cables, also this explains that the shorter Elgato TB cable seems to have less disconnects then the longer Apple cable, it should have less voltage drop then the longer Apple cable . When you compare now the SATA connector, you will see 3 parallel PIN's for power connection to lower contact resistance and carry the amperage, now the same current shall flow over a single and a lot smaller connection PIN20 on the Thunderbolt connection. This means for me,  stay away from Thunderbolt BUS powered devices, they will continue to have issues as long the power can not be reduced to flow over this one PIN, or a different connector will be used for the power. The chance is very high that the TB power controller in the MBP is causing this voltage drop and causing the disconnect alone or in combination with the Seagate portable adapter.

To find the real source of the power "switch off" it would be necessary to make more measurements, specifically it would be necessary to measure the voltages on the Thunderbolt connector on MBP and also Seagate TB adapter during usage. for this a Thunderbolt breakout connector would be needed to attach the test strips. This would identify where the power cut off happens. I was not able to find a place to buy a Thunderbolt male and female connector, alone without cable and without electronics to build this breakout connector. I would appreciate if someone could let me know a source for this connectors to perform this tests.

How to make this work?

The problem seems to be that overall/average power consumption of the Samsung SSD is on the limit what the MBP (or other computer) can supply over the TB connection, but has sometimes current peaks above what the TB power controller when getting hot, in the MBP and or in the Seagate portable adapter will except, before switching off the power to protect the TB connection (the 12 ms drop of supply voltage).

The dirty way, but NOT recommended to solve this problem, is to use capacitors to store energy for this peak use. What works, you can connect following capacitors in parallel to black and red power supply lines on the SATA extension (observe the polarity of the Electrolytic capacitor)
  • 1000 uF Electrolytic Capacitor, minimum 15VDC
  • 10uF Film Capacitor, minimum 15VDC
  • 10nF ceramic Capacitor, minimum 15VDC
  • SATA extension cable short
Here the circuit, and how it looks

3 capacitors with barrier strip connection
SATA extension with mounted capacitors



Why 3 different capacitors? each capacitor has different speed, the electrolytic capacitor stores the biggest energy but is slow, while the other 2 capacitor will act faster and on higher frequency, and shall suppress EMI and oscillating of power circuit.

Why shall this modification not be used? The 1000 uF capacitor has a very high inrush current, this means anytime you connect the Thunderbolt cable, the power controller has to regulate down the current until the capacitor is charged, and current over PIN 20 will go to the maximum current allowed......and in the longer run, may fry the TB connector in MBP or the TB cable.

Here the implementation I used for the test, it passes always the Black Magic Speed test and also to copy multiple 41GB vmdk files.


So what's the better way to make it work?

You need to use an external power supply for the SSD and the TB bus only powers the cable and the TB adapter circuit. This reduces also the power over the TB cable and hopefully also extends the contact live on the TB connector of MBP and TB cable. As I do not have any information how the power up timing and signaling is implemented in the TB connection, we must make sure that the power up timing is not changed when we use a external power supply. For this reason we need a relay that gets powered from the Seagate TB adapter (when the SSD shall get switched on) and then switches the power from the external power supply at the correct moment to the SSD when the TB cable is connected to the MBP. (external power supply needs to be connected to power line bevor you connect the TB cable to your MBP)

What we need:
  • 5VDC 2 Amp stabilised power supply or a 5VDC external battery with minimum 4000mA and 2A current rating, like external battery for an iPad
  • 5VDC Relay with low coil current (50mA or less) and single or multiple contacts to switch 2 Amp at 5VDC (you should switch 2 contacts in parallel for extended live)
  • SATA extension cable
Note:
You can NOT use a dual USB cable to power the SSD from your Laptop's USB connectors! The power to your SSD connected via Thunderbolt must be a floating power supply, same as you can not power a USB hard disk from same power supply as your PC mother board is powered from (you would create a ground loop and bridge some circuits). If you do so, you can damage the laptop, Mac or Thunderbolt adapter, TB-cable, SSD or all of them. The minimum effect is that you will have a lot of data errors. So you must use an independent floating power supply or an independent battery.

Here the recommended circuit




Here the complete SATA cable with relay and PSU:

SATA extension with relay switching 5VDC from external PSU to the SSD
This contraption passes all the tests and in my opinion can handle continuous use.

Some things to keep in mind

Does this MOD make any sense? You spend 99 bucks and have to add a relay and then also a stabilised 5VDC power supply and a couple of hours to make this work? Also the portable adapter has only one TB connector, so you can not daisy chain any other TB equipment.

In my opinion, using the Seagate TB desktop adapter with a short SATA extension cable is the better solution in the long run. (The desktop adapter comes already with a external power supply, has no power issues with large SSD's and for my knowledge has no thermal issues when used with 2.5" disks and a SATA extension)

To left: Seagate Thunderbolt Desktop Adapter with SSD in GoFlex case and SATA extension cord.





















For continuous use of your Thunderbolt devices (and also a Mac mini or iMac) You should keep in mind, special in countries with 110VAC line voltage, that there are a lot of power spikes, they do not effect the MBP, because it has a built in battery acting like a uninteruptible power supply, but all spikes will go thru any standard power supply to the TB adapter, and as known from this site http://support.apple.com/kb/HT5219?viewlocale=en_US any wrong sequence of connecting disconnecting Thunderbolt devices will lock them up. This means also when power spikes make the MBP believe the TB adapter was short time disconnected (indiced by power spikes) will cause a disk disconnect error message or will make your TB equipment "invisible" until you reboot your MBP again. To avoid this, you can use a small PC UPS to power the external power supply from the Seagate desktop adapter or when you use the portable adapter with the relay design you could power the portable adapter not with a power supply, but with an external battery (you need a high power version with minimum 4000mA capacity and 2 Amp current) similar like this http://store.apple.com/us/product/H6094ZM/A/mophie-juice-pack-powerstation-external-battery-for-iphone-ipad-and-ipod 


Thunderbolt Stuff

You should read the FAQ/dont's listed by Apple http://support.apple.com/kb/HT5219?viewlocale=en_US and check the MAC forums that there are multiple complaints about sleep issues, or coming out of sleep with TB devices. I found out in the hard way that you can NOT have plugged in a Thunderbolt cable alone in your computer if on the other side of the TB cable is nothing plugged in. If your MBP will go to sleep with the TB-cable alone, the MBP crashes during sleep, or maybe when waking up from sleep and you have to boot up your MBP from a powered off state, needless to say that my  W7-VM was crashed..... So avoid this.
I have my Mac always set to automatic sleep after few minutes, but I use Caffein http://lightheadsw.com/caffeine/ to prevent my MAC from sleep during testing or when I do important work.

Some Thunderbolt information:

Semtech TB cable transceiver 

Texas instruments

Intersil TB chip

Intel TB controller less then 3.4 W

Thunderbolt Cable

Thunderbolt device reviews

Thunderbolt 10W, pin 20

Displayport and mini Displayport info

SSD tests with power consumption info

How to measure power consumption of SSD