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Secrets of Thunderbolt and Lion

You can read a thousand articles about the new Thunderbolt input/output technology in Apple’s latest revision to MacBook Pro laptops, and the new revelations from Apple about Mac OS X Lion. But via Twitter, I discovered that many people are unaware of or concerned about certain features close to their hearts. From online sources and a briefing with Apple last week, I can provide some reassurance and additional details.

These seem to be among the least well understood and documented items about Thunderbolt and Lion.

Thunderbolt’s Blasts -- Thunderbolt is a fascinating mix of old and new:

  • Despite what the tech spec pages say, Thunderbolt actually has up to 20 Gbps available in each direction (full duplex), not 10 Gbps. While the Thunderbolt specification talks about 10 Gbps to and from a host, there are actually two channels over the same cable: one dedicated to DisplayPort for video, and the other for PCI Express data. Apple and Intel are likely sticking with the 10 Gbps rating because if you measured the throughput to a hard drive, for example, it would never go over 10 Gbps thanks to using only the PCI Express channel.

  • This dual-channel approach would let you run two high-resolution displays (which require bandwidth in the gigabits-per-second range) and a super-fast RAID drive (demonstrated by Promise Technology) or multiple drives that can work at full speed. On the new MacBook Pros, Thunderbolt manages both the internal screen and an optional external display, which is why you can’t drive two external displays. On a future Mac Pro or Mac mini that wouldn’t be an issue, nor would it be a limitation on a future iMac, as long as the iMac provided multiple Thunderbolt ports.

  • Because Thunderbolt provides two channels on the same cable, a display or hard drive can be in the middle of the daisy-chain without interrupting the flow of the other channel.

  • Target Disk Mode is supported under Thunderbolt. Until now, this mode worked only over FireWire connections. When a Mac is booted in Target Disk Mode, it acts as a hard drive for another connected Mac.

  • You won’t be able to boot a Mac from a Thunderbolt-connected drive for now, unlike with USB and FireWire. Andy Ihnatko has this factoid, and I tend to trust him. I will be surprised if this isn’t added later. We need a way to boot from external drives, and if Thunderbolt eventually takes over from FireWire, then it has to boot Macs, too.

  • If all you’re connecting to a Thunderbolt port is a display, you can using an existing DisplayPort cable. The Thunderbolt controller automatically adjusts the signal output to be correct for DisplayPort-native ports on the other end. Thunderbolt data devices, such as hard drives, need to be connected with Thunderbolt cables. This means you can’t put any Thunderbolt data devices downstream from a display connected via a DisplayPort cable; such displays would have to go at the end of the Thunderbolt daisy-chain.

  • The Thunderbolt port carries 10 watts of power, a significant amount for powering drives and other peripherals (though nowhere near enough to drive a large external display). Apple’s hardware with a single FireWire 400 or 800 port (or one of each) can deliver 7 watts to the bus. USB 2.0 can push out a maximum of 2.5 watts, while USB 3.0 can hit 4.5 watts. Apple’s high-power USB 2.0 can generate 5.5 watts, which is enough to charge an iPad while it’s plugged in and in use. Thunderbolt devices can also boost power downstream: an AC-powered display could push 10 watts out the port on the “far” side from the computer in the daisy-chain. (Apple’s external iPad USB-to-AC charger is rated at 10 watts, but it’s just a USB plug connected to power, not a data connection.)

  • Thunderbolt will allow splitters and other baroque configurations of adapters, Apple told me. For instance, you could have a DisplayPort adapter with two Thunderbolt ports for daisy-chaining. Apple has no plans to discuss here, but there’s clearly room for a robust market of cables, hubs, adapters, and other elements to make it easier to use legacy video standards.

  • It should be possible to build Thunderbolt-to-eSATA and Thunderbolt-to-FireWire adapters that enable connectivity with older gear that you already own. It’s also possible that we’ll see Thunderbolt-to-USB 3.0 adapters, though it probably doesn’t make much sense to convert between Thunderbolt and USB 2.0 given the low cost and ubiquity of USB 2.0 parts. A company could create a dock-like device that would plug into a Mac via Thunderbolt and provide a slew of USB, FireWire, eSATA, and other ports.

Lion’s Roars -- We have to keep mum on many Lion details, as many of us at TidBITS are enrolled in the developer program that gives us access to non-public preview details. However, on the public side:

  • Lion’s AirDrop will let you exchange files between two Macs (and, one expects, iOS 5) using Wi-Fi. But it’s not a variant on Bonjour: the two Macs do not need to be connected to the same Wi-Fi base station or larger Wi-Fi network. Rather, they only need to be within Wi-Fi range of one another. AirDrop uses a peer-to-peer ad hoc connection, though one that’s instant to set up and secure. A Mac using AirDrop doesn’t drop a Wi-Fi network connection if it has one; it can communicate to another Mac and maintain its network connection, too. This requires newer hardware. I suspect nearly all machines shipped since 2007 or 2008 will have the right Wi-Fi gear, but Apple will need to provide more details as Lion’s release date gets closer.

  • Lion’s FileVault is an entirely new bit of technology labeled with the old name. FileVault before Lion encrypted only the user’s Home directory and was awkward in everyday use. The new FileVault is a full-disk encryption method: everything on the hard drive (and it seems, external drives, if you wish) is completely secured. Apple didn’t explain whether you will need to enter a password at boot, as is the case with many existing full-disk encryption products for Mac OS X, Windows, and Linux. You may also be able to wipe a FileVault-protected Lion system remotely. Apple told me that the new MacBook Pro models will use accelerated encryption processing in the i5 and i7 processors to eliminate any performance loss due to handling encryption.

  • Mac OS X Server is built into Lion, although it apparently will not be active when you upgrade or boot a new machine. Apple declined to provide details, but said that reports that you had to make a choice during installation of Lion, or reinstall Lion to use server features, were inaccurate. You will have to activate something within Lion, though what form that will take, or if it will be available for free remains unknown. I wouldn’t be surprised if you would pay for the upgrade in the Mac App Store in some way.

Keep the questions coming.


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Comments about Secrets of Thunderbolt and Lion
(Comments are closed.)

Great Post & an excellent Summarization of new MacBook Pro features. Appreciate it.
Apple modified the Server license to allow virtualization on Apple hardware. Will Lion allow this as well?
Glenn Fleishman  2011-02-27 04:56
This isn't currently known. Apple's revealing just a little bit at a time.
James Katt  2011-02-27 18:26
The answer is NO.

Mac OS X Lion - despite being also server capable - is NOT Mac OS X Lion Server.

Virtualization will not be allowed - just as in the consumer versions of Mac OS X.
Glenn Fleishman  2011-02-27 18:34
Now, how do you know this?
Bfredit  2011-02-27 19:45
According to Apple's current website, "Lion Server is now part of Mac OS X Lion" therefore, I assume, Lion Server can't be bought as a standalone. This means that I, Snow Leopard Server owner, should still be able to virtualize my OS when I'll upgrade. Failure to allow virtualization will kill OS X Server as we know it.

But do not trust my words, just wait and see.
Curmudgeon Geographer  2011-02-27 04:56
Anything about new malware protection? Snow Leopard added some profiles for a few trojans that could be watched for when downloaded. Anything new in this regard?
Glenn Fleishman  2011-02-27 05:41
No news in that regard yet. A great sign of Apple waking up to this is that they contacted (unsolicited) several security experts known for making strong public critiques and analyses of Apple's methods to get them a developer preview to look at. That's awfully encouraging.
Um, last I checked, it wasn't WATTS that a USB port only delivered 2.5 of. It was Amperes, or Amps, for short. You might want to get your electrical current specifications correct.
Glenn Fleishman  2011-02-27 05:53
That's incorrect. 2.5 amps would an extremely large amount of amperage to come out of a computer interface port.

As you probably know, watts = volts times amps. Power adapters are typically measured in the number of watts provided; Apple's adapters are listed as 10 watts (iPad) or 60 watts or what have you (see the Apple Store online for how they describe laptop adapters, for instance). So it's better to use the apples-to-apples terms for clarity.

Normal USB 2.0 offers 5 volts at 100 to 500 milliamperes (mA), which is 0.5W to 2.5W (the higher voltage requires a controller negotiation for an active device). Apple boosts its high-speed port to 5V at 1100 mA or 5.5W.

USB 3.0 allows for 5V at 150 mA up to 900 mA, which is a maximum of 4.5W.
2.5 amps would probably make most USB devices explode into flames
lol... somebody needs to get their specs right.
sgtrich  2011-02-27 06:40
Went to an Apple store Saturday afternoon just to look at the new MacBook Pros. The new AMD graphics are TERRIBLE! The screen appeared to be blurry compared to my own year-old MacBook Pro.

Also, regarding Mail 5.0 in Lion, I certainly hope that Apple gives us the option to keep the Mail 4.0 layout. I primarily use my 24" iMac for email. I do NOT want to be limited to the small screen look that users of iPhones and iPads get. Don't take away the option to use the full screen on my iMac just to make Mail appear more like on an iPhone or an iPad. There's no upside there!
Glenn Fleishman  2011-02-27 15:30
I wonder if the demo machine was set to a non-1:1 ratio of pixels? It's possible someone was messing with the display and it hadn't been reset. You can choose to have a resolution appear that's not perfectly aligned. Or it could just blurry.
Kerrigore  2011-02-28 21:38
>The new AMD graphics are TERRIBLE! The screen appeared to be blurry compared to my own year-old MacBook Pro.

The graphics card being used cannot have this effect, it must have been another factor.
johnsmith  2011-02-28 23:48
Really - I actually find that a 3 pane view for mail works much better on a larger display. You should give the free mail add on called letterbox a try - it actually predates iOs and makes mail look a lot like Mail 5.0. I am guessin that most people really don't need the full width of the screen to display a single mail - most of it would be white space -and it is nice to be able to see a longer list of mails. Give it a shot and see.
Of course, each to their own, if you don't like this setup don't worry Lion gives you the option to use the "classic" view if you want.
How can Thunderbolt support Target Disk Mode, but not booting? In order to support Target Disk Mode, the Mac *has* to boot via Thunderbolt, no? Is Andy just saying that none of the Thunderbolt disks available right now can be used to boot, but that the technology would allow for such disks to exist?
Target Disk Mode is NOT used to boot your Mac off an external drive - it is used to make the internal disk on your Mac appear as an external attached drive to ANOTHER Mac. For instance if you want to run a full offline iDefrag or a Carbon Copy Clone of your internal drive - you boot your Mac in Target Disk Mode - which does not mount and load the OS on your drive but rather turns your entire system into an external storage device to be mounted by the OS running on a second machine.

To boot to any device - the hardware and firmware in your machine must be able to scan the bus and detect a mountable volume and read from the filesystem on that device. Which at a high level seems like it would not have requirements very different from Target Disk Mode - but I am not a device driver developer or chip programmer so I don't know what the limitation may be or how easily they can be removed.
Ah, right, you don't necessarily need to be able to boot from the disk of a Mac that's attached via Target Disk Mode. I just assumed this was part of TDM without really thinking about it.
Grover  2011-02-28 19:54
Don't feel bad. I had the exact same reaction since that's nearly always what I'm doing with Target Disk Mode.
odysseus  2011-02-27 17:33
"Apple told me that the new MacBook Pro models can use accelerated encryption processing in the i5 and i7 processors that eliminate any performance loss due to handling encryption."

What about the i5 processors in the mid-2010 MacBook Pro models?
Glenn Fleishman  2011-02-27 17:53
They didn't address that. I'm presuming that when Lion ships, there will be a lot of asterisks about AirDrop, FileVault, and other features that are heavily dependent on specific CPUs and GPUs.
Their longterm engineering approach seems to be to get the low level work done a generation in advance, and then expose it on the next cycle. So I’m betting that this here recently “obsoleted” i5 MBP has the necessary bits to use both FileVault 2 and FileDrop.
Bregalad  2011-02-28 22:13
Yes. All Core i# processors built on the 32nm process have hardware accelerated AES encryption/decryption. That means the MacBook Pro and iMac are supported.

Most current Mac Pros are built around the older 45nm Nehalem design so they may suffer some performance loss from full disk encryption.
Curmudgeon Geographer  2011-02-27 18:25
Snow Leopard made steps towards unifying scanning for users. Image Capture, the Printer Queue for multifunction devices, and Preview's File>Import from Scanner each worked nearly identical, but there were some slight differences.

Finding where to go to to scan was the trouble. Has setting up a scanner and scanning been made easier?
Curmudgeon Geographer  2011-02-27 18:37
Any changes to ToDo's in iCal and Mail?

Does setting up Gmail in Mail still litter Mail with Gmail's labels as mailboxes? Does "All Mail" still show up in Mail? Mail in iOS knows to "Archive" emails from Gmail (instead of Delete), does Mail in Lion do this trick too?
Rachel  2011-02-28 23:09
Gmail exports labels as mailboxes via IMAP, so if you connect to Gmail via any IMAP client -- not just Mail -- you get those labels as mailboxes.
Josie Newman  2011-02-28 00:37
Any word on whether Lion will still include Rosetta? I am still not ready to give up on my beloved Eudora, no matter what anyone says.
Glenn Fleishman  2011-02-28 01:07
The suspicion is that it will not be included in the shipping release. But there is no official word. I can't say whether or not it's in the developer preview, but even if it were there or missing, things can change by the shipping date.
There may be no official word, but Rosetta is absent from the developer preview, and the wording of the dialog box seems quite unequivocal
M. Perry  2011-02-28 16:09
Look at that MacBook in profile. Apple's still not fixed the #1 problem with laptop ports, that out-sized, difficult-to-use Ethernet port. A MagSafe equivalent would be marvelous. Making it a world standard would be even better.

And no, Thunderbolt isn't an Ethernet replacement. You can wire an entire office building with gigabit Ethernet. The distance limitations on Thunderbolt won't get you to the next room.
Glenn Fleishman  2011-02-28 17:15
I've seen low-profile Ethernet plugs before; I have no idea why the industry hasn't moved to something more sensible. It's certainly not necessary.

However, what I suspect Apple's next move will be is to offer Thunderbolt-to-Ethernet adapters. It sounds like this should be easily possible, just like USB-to-Ethernet adapters, which were introduced for the MacBook Air and work on any Mac.

I suspect 98% of Mac laptop users never or very rarely plug into Ethernet, and Apple could make that switch to reduce port cost and complexity (and make thinner laptops like the Air).
odysseus  2011-02-28 19:08
I think you're vastly underestimating the number of laptop users who plug into ethernet. There are huge numbers of people on my college campus who use wired ethernet. In addition, it's still necessary if you're transferring large files -- gigabit ethernet is *way* faster than any version of Wifi.
Glenn Fleishman  2011-02-28 19:25
Good points. The question will be if Apple decides Ethernet is like the floppy disk sooner than we're ready for it. MacBook Air users have to rely on an Ethernet (100 Mbps only!) adapter, which always seemed like a shame.
Or indeed syncing your Apple TV for the first time
Yep, like the USB-Ethernet for the AIr but no speedlimit on a thunderbolt-ethernet adapter like the Air.
Funny thing about Ethernet is it only uses 4 of the 8 wires in that connector. It is a waste of space to continue to use that form factor but the spec for Ethernet requires it.

I remember using 4 wire phone cables (RJ-11) when I needed one in a pinch and and they worked just fine. Just had to snip the connectors off and wire it into a 8 pin RJ-45.

Also, I agree with below about E'net usage. I use it exclusively when at home or at any office I work at if available. All of my devices, DirecTV, AppleTV, laser printer all use Ethernet.

WIFI just isn't good enough for me... yet.
Glenn Fleishman  2011-03-01 22:15
Gigabit Ethernet uses all eight, and it's designed (with twisted pairs and a twisted cable) to run quite long distances. However, flexible cheap optical cable would be far better all around, so long as it's not easily crimped or broken.
Steven  2011-03-09 05:23
I connect to one every day. I long for a docking station and perhaps Thunderbolt is the key to getting one done at last.
Andrei  2011-02-28 21:03
Thunderbolt is only copper for now, but later on it will have the possibility of using optical cabling which will enable it to work over very long distances — probably even beating ethernet which starts to lose it's speed around 100 meters.
Thunderbolt's distance limits for COPPER CABLESis 3m and that makes copper cable thunderbolt a non-starter for networking. However, optical cables will have much longer cables, possibly up to 100m, almost certainly up to 30m which makes networking a real possibility.
Jim Thompson  2011-02-28 18:46
I wonder if AirDrop will be available on iOS devices, too.
Glenn Fleishman  2011-02-28 23:08
I hope so! It's perfectly within the capabilities of the devices and the later-generation Wi-Fi gear in the last 2 or 3 years' worth of them.
Jim Thompson  2011-03-01 04:14
So Apple finds a use for the new ad-hoc connections in 802.11, which is a hollaback to the old AppleTalk/Localtalk ability to throw things to a remote Mac user's "public folder".


It will be Tres Cool if the iOS devices get this. Imagine being able to throw the latest version of some file to a friend across the coffee shop, or office.

It's too bad this wasn't built with Bonjour^WRendevous though... then we could fling crap across the continent, and Apple would have fixed the largest source of email annoyance: namely, that it's used as a transport protocol for large attachments.
I have a question regarding processor support:

Anyone know if it runs on all Mac Pros?

I heard it doesn't run in Core Solo or Core Duo. Does it run in all Xeon-based Macs?

Any info will be greatly appreciated!
Yes, almost certainly. Core Solo/Duo chips lack 64-bit support, but even the earliest Xeon-based Macs used a 64-bit capable processor (one from the same family/generation as the Core 2).
That would be awesome. I don't think I am ready to replace my almost-four-year-old Mac Pro... it still works great and I have no reason to replace it. Though it would make me really mad if I can't install Lion on it.

Does anyone know of a place where I can ask Apple directly about it? I guess I'll have to wait until it gets closer to release so they disclose more info on it.

Let's hope for the best.

Thanks for the reply!
Jeff Carlson  An apple icon for a TidBITS Staffer 2011-02-28 23:34
I asked Apple directly about system requirements for Lion, and they said they aren't sharing that information yet. We'll know closer to launch in the summer. Four years tends to be on the "doable, but not ideal" scale of system performance, so we really can't say yet whether Lion would require a new machine in your situation.

Thanks for sharing. We'll have to wait.

I understand the 'doable, but not ideal' argument. But I would expect a better 'shelf life' on Mac Pros since they are anything but 'entry level'. Again, there's only hope. =)
According to the leaked developer docks, all 64 bit capable machines can run Lion and that includes my 2006 MacPro. First gen minis are out of luck.

Making Lion only 64-bit makes sense, and this might be why Rosetta is possibly being eliminated.
Thanks for keeping the hope up! :)
Ted Todorov  2011-02-28 19:58
Front Row is apparently missing from Lion. Will it be replaced by something else? Will that something else provide support for DVDs/VIDEO_TS files the way Front Row does? Has the Apple DVD Player software been changed in Lion?
What's it going to take to hook up two legacy DVI displays to a Thunderbolt port?
Glenn Fleishman  2011-02-28 20:21
Some kind of new adapter (and not having a laptop). With the laptop, you'll only be able to drive one external monitor, since the same graphics system is running the internal display. (Update graphics could change this in a future release, as I expect the internal laptop display is run via DisplayPort, while the external one is DisplayPort-over-Thunderbolt. Meaning that you'd still have one Thunderbolt slot free if the graphics card could handle three monitors.)

On a future Mac mini or Mac Pro, you'll need some kind of adapter that has two Thunderbolt ports for daisychaining the first one, and an adapter for the monitor. The second one will work with a normal DisplayPort adapter.
Interesting details about Thunderbolt. You have dashed my hopes that the new MBP would allow for dual independent external displays (even if that means the internal display would be shut off).

I'm confused now as well. I had assumed that Thunderbolt had 2 full duplex 10 Gbps links in addition to the DisplayPort link. I have read the DisplayPort v1.2 spec that it can go as high as 17.28 Gbit/s which would be much to high for a single TB link to handle?
Glenn Fleishman  2011-02-28 20:23
Apple could update the video card in future laptops to allow this, I believe.

Thunderbolt does have 2 full duplex 10 Gbps links, but Intel's documentation makes it clear that one channel is reserved for PCI Express data and the other for DisplayPort data. So you're effectively limited to 10 Gbps (raw) for anything external on either port.
roosto  2011-02-28 22:39
TUAW reports that 2 external displays *are* supported [], citing Apple's Australia site []. The last section on the Apple AU page states, "[with] the Thunderbolt port: You can daisy-chain up to six devices, including up to two high-resolution displays*." The footnote says only the 15" & 17" models support 2 displays. The copy on Apple's US site is vague as to how many displays, and makes no mention of lesser support for the 13" (which doesn't have the dedicated GPU). I suspect the Australia thing is a mistake (UK, Canada, and France have the same vague language).

Whatever the exact limit for displays on the channel dedicated to DisplayPort data, designing some sort of external video 'card' that would work off the PCI Express bus channel is possible, no? Obviously that would eat up a chunk the PCI channel's bandwidth, but even half of 10 Gbps is a lot bandwidth.
Glenn Fleishman  2011-02-28 23:07
Apple specifically told me the laptops would only support the internal monitor and one external monitor. The Thunderbolt spec allows for up to external monitors, but that is dependent on the graphics capability of the device.

But you're right: an external video card on the data side could work.
Ron Manke  2011-02-28 20:39
Raising questions about whether Lion Server is free? Hmmm.

Apple states on their website that "Lion Server is now part of Mac OS X Lion", so to then go back and say "at an extra charge" would be very misleading.
Glenn Fleishman  2011-02-28 20:47
You're quoting precisely the problem. I asked Apple point-blank: will it be free? will you pay an upgrade fee? They said they weren't ready to talk about that. So. If it were included, instead of "part of," you could see where they would have had a simpler answer.
Or, it could simply be they were saying it is included, in the package, not meaning it is included in the price.

Maybe that is why they are tight-lipped on the pricing side.

I think they simply meant you will be able to use one installer for either/both. Pricing will come later.
John Harrison  2011-02-28 21:06
I was hoping for a monitor refresh that would support the ThunderBolt port, or at least the release of a hub. At the moment it seems that all the port is good for is plugging in to a monitor and for now that is the end of the line.

An ideal setup would be to have all my devices connected to an external monitor and be able to plug them in to the MBP all at once. With my current setup I have to plug in five or six cables to use the laptop as a desktop. I'd like a bit more clarity on how things are going to work before upgrading.
Glenn Fleishman  2011-02-28 21:21
Hey, give them a few weeks!

It'll come. I suspect Apple will tweak its whole monitor line, and have a hub or daisy chain. From what I can tell, you can have Thunderbolt hubs, but if they're not in the computer (as additional integrated ports), you're still sharing the same channels on the wire.
jehrler  2011-02-28 21:39
FileVault question. Currently to use TimeMachine and FileVault you have to log out of your FileVaulted account to have TM back up the sparsedisk of your home folder.

With the new FileVault will TimeMachine become seamless for these users and just do its thing when the user is logged in?
Glenn Fleishman  2011-02-28 22:02
No idea yet. Because the new FileVault is full-disk, the computer is only usable when it's booted with the password entered. This could leave Time Machine as vulnerable, because data backed up to it could be password free unless Apple also updates Time Machine (and Time Capsule) backups.
Susan Wong  2011-02-28 23:27
Disk utility now supports encrypted external volumesso no worries there.
Does Lion have the ability to set a program to open "Maximized like Windows? (Full screen will be nice for those with a trackpad and a small screen but not so hot for those with large screen and a mouse). I get this question from clients all the time.

Second question, does Lion have larger mouse pointers? Clients constantly complain about the small mouse pointer on their 27 inch screens.
Glenn Fleishman  2011-03-01 04:14
I don't know about Lion and big windows, but you can use the free Right Zoom for that:

For cursors, this is already in the Universal Access preference pane. Open it, then click the Mouse (or Mouse & Trackpad) tab. At the bottom, you can resize the cursor to super huge.
Thanks, I will have to look into RightZoom. In regards to mouse size I am aware of the option in universal access, however, the enlarged pointers are very jagged. If Apple would release non-jagged medium and large pointers my clients would be thrilled.
Paul F Henegan  An apple icon for a TidBITS Contributor 2011-03-01 09:28
How long until Magma announces a Thunderbolt host connection for their expansion boxes?
Michael Wenyon  2011-03-01 16:27
Yes, and doesn't ThunderBolt on a Mini become a viable option to a Mac Pro for a greater number of users?
I have been using the Developer Preview for a while now. I am amazed at how stable and well done it is already.

Not saying anything else, but it is a nice release.