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Thunderbolt on your Mac

Apple has always been on the leading edge of connectivity for their systems.

Back in 2003, before we had formed Small Tree as a company, I can recall drooling over a Power Book laptop with an integrated Gigabit port. That was a crazy thing to have on a laptop at the time. Gigabit was still a little weird, very expensive, and not common as a drop at anyone’s desk. Yet here apple was putting it on a laptop.

Thunderbolt is a similarly aggressive move. It puts a great deal of IO horsepower on some very small systems.

Firstly, let’s consider what Thunderbolt is. Thunderbolt is a 4X (4 lane) PCIE 2.0 bus. It’s equal in performance (and protocol) to the top two slots of a traditional tower Mac Pro. Along with that 4X pipe, there’s a graphics output pipe for a monitor. These pipes are not shared! So using a daisy-chained monitor will not impinge on any attached IO devices.

Thunderbolt is capable of moving data at 10Gbits/sec FULL DUPLEX, meaning data can move in two directions at the same time, giving the pipe a total bandwidth of 20Gbits/sec.

As I read through the forums and opinion articles on Thunderbolt, one of the themes that pops up is “It’s Apple proprietary and expensive. Just use USB 3.0.” This is a reasonable point. USB 3.0 is capable of 4.8Gbits/sec (about half of the speed of Thunderbolt). Further, there are plans to speed up USB 3.0 to 10Gbits/sec to match Thunderbolt. So given these factors (and the low cost of most USB devices), it seems like an obvious choice.

However, there are some reasons that Thunderbolt may win the day for external high-speed connectivity (and relegate USB to it’s traditional low-end role).

First of all, most IO chips (Ethernet, SATA, SAS) are manufactured with a native PCIE backend. The chips are natively built to sit on a PCIE bus. So not only will you save the overhead of an additional protocol, the guys writing the code to support these devices only need to write one driver (PCIE). It just works whether the device is on a card or in a Thunderbolt toaster.

Another advantage of Thunderbolt is its power budget. Often, devices are powered by the port itself (very common with USB). USB can provide 4.5Watts of power to attached devices, whereas Thunderbolt offers a full 10Watts of power.

Lastly (and this is probably the most interesting thing about PCIE and Thunderbolt) is that Thunderbolt is a switched/negotiated protocol that is extremely flexible. Cards that want a 16X slot can work in a 4X slot. PCIE switches can (and do) exist to allow multiple machines to talk to one PCIE based device (like a RAID). So imagine a time in the future when devices can be connected to a “switch” in a back room and multiple systems can see them. Imagine those systems can have multiple connections to boost their bandwidth.

Thunderbolt may not be everywhere yet, but it’s really the first imaginings of a new way to handle IO outside of the “tower” type machines. I think it is easily the best choice for Mac users and will likely offer some amazing benefits in the next generation.

Posted by: Steve Modica on May 24, 2013 at 12:13:41 pmComments (3) thunderbolt, storage

Thunderbolt growing pains

We've been selling a lot of thunderbolt stuff over the last couple months and I've been very pleased with the performance and convenience of the products. Thunderbolt seems to be a big win.

As with any new technology, there are always a few growing pains and I wanted to bring one of them up here in my blog.

As with any new technology, vendors trip all over themselves trying to bring it to market. Everyone wants to rush through testing so they can be first. Likewise, cable vendors want to do the same. They source the connectors, get the molds made, solder everything up and shoot the injection molds and they've got $20 cables on Amazon before you can blink.

The problem of course, is that these cables vary widely in quality.

High resolution monitors and high frequency, high bandwidth cabling requires a lot of interference management (this is in part why all your monitor cables have those big fat lumps molded into the middle of the cable.) Those lumps are ferrites and selecting the correct one for the application is actually quite involved. You can read about it here:

Depending on the engineering, time and testing put into the product, your success with these cables may vary.

So be prepared when you order monitor cables and thunderbolt cables online to see problems like flicker, intermittent operation or downright failure. You may have to try a vendor or two before you find the right one. Be sure to look at reviews!

Over time, I expect to see both peripheral and cable vendors approach some happy medium as they all figure out what works best.

Posted by: Steve Modica on Nov 7, 2012 at 1:41:19 pm thunderbolt, monitor

iSCSI madness

Next week we start testing 10Gb (10GbaseT) iSCSI attached to new imacs with Thunderbolt using MPIO to hit 30Gbits/sec back to storage. It's going to be AAAAAWesome. What's really cool is that the iSCSI driver enables Xsan, so it's all compatible.
Previous testing with a single 10GbaseT port showed we could go faster than Fibre Channel. I expect 3 10GbaseT ports will go much much faster!

Posted by: Steve Modica on Oct 19, 2012 at 1:10:48 pmComments (3) thunderbolt, xsan

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