Hi,

Does anyone know - definitively - whether mixing firewire 800 and 400 devices on the same chain drops the bus speed to 400?

Does the 400 device placement in the chain affect things?

I have heard that by putting it at the end of a chain, the rest of the devices can stay at 800.

I have a new Unibody Macbook Pro with only 1 x FW800 port (Nice one Apple), 3 x FW800 hard drive and a FW400 soundcard.

I'd like to retain FW800 speeds for the drives.

All suggestions gratefully received.

Cheers.

Rich

Edited by blastmasterd (16/01/10 09:19 AM)

Quote blastmasterd:

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Hi,

Does anyone know - definitively - whether mixing firewire 800 and 400 devices on the same chain drops the bus speed to 400?

Does the 400 device placement in the chain affect things?

I have heard that by putting it at the end of a chain, the rest of the devices can stay at 800.

I have a FW800 hard drive and a FW400 soundcard.

All suggestions gratefully received.

Cheers.

Rich

---

On my macbookpro I do exactly that and yes it does drop it all to 400 and no it has not caused me any probs at all

I use either a Motu Ultralite or a Saffire pro24 and gtech drives

--------------------
Matt
www.krcollective.org

Hi Matt,

Thanks for your answer.

May I ask if you've tried moving the FW400 device to the end of the daisy chain to see if it allows the FW800 devices to stay at 800 speed?

Cheers.

Rich

I was about to write, yes, just connecting a FW400 anywhere on the chain drops the whole bus to FW400 speeds, as that was my understanding - but I thought (always a good idea) to do a quick (non-scientific) test myself.

On an MBP with a hd connected via FW800, I loaded a 1.5gig file into memory (Photoshop) and saved it back to the FW800 drive.

I then connected an FW400 device on the end of the chain, after the FW800 drive, and repeated the test, and yes, the transfer times were longer, indicating that having the FW400 device at the end of the chain does indeed impact on the bus speeds. (Write speeds were nearly twice as long, for instance.)

Try a test yourself in various configurations, repeating each test a few times and averaging out the results. I chose to read into memory and write from memory to try and factor out additional drive speeds when copying files between drives, but like I say, it wasn't a particularly scientific test.

Quote desmond:

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I was about to write, yes, just connecting a FW400 anywhere on the chain drops the whole bus to FW400 speeds, as that was my understanding - but I thought (always a good idea) to do a quick (non-scientific) test myself.

On an MBP with a hd connected via FW800, I loaded a 1.5gig file into memory (Photoshop) and saved it back to the FW800 drive.

I then connected an FW400 device on the end of the chain, after the FW800 drive, and repeated the test, and yes, the transfer times were longer, indicating that having the FW400 device at the end of the chain does indeed impact on the bus speeds. (Write speeds were nearly twice as long, for instance.)

Try a test yourself in various configurations, repeating each test a few times and averaging out the results. I chose to read into memory and write from memory to try and factor out additional drive speeds when copying files between drives, but like I say, it wasn't a particularly scientific test.

---

Hi Desmond,

First off, thanks for carrying out this test.

I think I will try it out also - Will have to borrow a firewire interface. I am thinking of buying a MOTU 828Mk3 (FIrewire 400) or a MOTU Ultralite Mk3 Hybrid (Firewire 400 & USB2).

This test might just sway me toward the Ultralite. Will let you know my results.

It is actually a bit tricky to do these tests, as if you are using a HD, usually the HD read/write speeds dominate the tests, making the evaluation of the bus speeds tricky.

I had rather flaky performance in Photoshop, especially in the writing, where it would vary quite widely. It would be better to test bus throughput with audio data or some real-time generated data or something.

I haven't done enough tests to say for sure that the speeds are dropping with the FW400 device connected - it looks that way, but I'm not confident enough in the quick results to go that far.

Interesting though...

I wonder if Martin W ever did some firewire speed tests for SOS? He kinda likes these testy things...

The basic problem of using hard drives to test this is:

From the net:
- Firewire 400's maximum transfer is 50 Megabytes per second.
- Firewire 800's maximum transfer is 100 Megabytes per second.

- The typical modern 3.5 inch 7200 RPM Hard Drives average read/write transfer rate is around 60 Megabytes per second.

Assuming those figures are correct: by doing file copies, typically the maximum performance you are going to get is roughly about what FW400 can support. So repeating the test with FW800 drives would *still* give you approximately FW400 performance, leading you to conclude (wrongly) that there is no speed difference.

I guess ideally what you need is to stream in audio to a DAW in real time from a FW400 and FW800 interface enough channels or at a high enough sample rate that will saturate up to the FW800 bus - thus, no drives used, and you can get a better idea of general bus speed differences...

I recently purchased a G-Raid drive and it included a Firewire 400 to Firewire 800 cable. I wonder in writting, would this make any difference in retaining the Firewire 800 bus speed?

Something tells me that this would not make a lot of sense but on the other hand, you never know...

Asuming the drive is natively FW800:-

If you're plugging in the FW400 end of the cable into a FW400 port, then you'll be getting FW400.

If you use a straight FW800 to FW800 cable, you'll be plugging it into an FW800 port, and providing there are not other FW400 devices present, you'll be getting FW800.

Basically, if you're plugging into an FW400 port, you won't magically be getting FW800 speeds, even if your drive can support that. FW400-equipped computers don't magically get FW800 support just because your pripherals can handle that speed - their chips won't support FW800.

As I understand it if you plug anything with 400 into an 800 port it automatically defaults to 400 as will all other devices connected to the same bus.

I was disappointed with my MacBook Pro which has 2FW 400 and 1FW 800 port. So I got an MBOX pro (FW400) and a G Drive for audio with FW 800.
I was really annoyed to find all the 3 ports on my MBP were on the same bus, and as soon as I connected anything to the FW400 port the 800 port also went down to 400. Very poor - and misleading.

As I understand it it's the same on my MacPro I just got - there's a couple of 800 ports but all on the same bus so if I put a 400 into one, the other goes 400. Only way round it is to get a PCI FW 800 card addition.

At least thats how I understand it all works\

Quote SparkyG:

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As I understand it if you plug anything with 400 into an 800 port it automatically defaults to 400 as will all other devices connected to the same bus.

I was disappointed with my MacBook Pro which has 2FW 400 and 1FW 800 port. So I got an MBOX pro (FW400) and a G Drive for audio with FW 800.
I was really annoyed to find all the 3 ports on my MBP were on the same bus, and as soon as I connected anything to the FW400 port the 800 port also went down to 400. Very poor - and misleading.

---

I'd be livid if that was the case...

My MBP just has one FW800 port. I am a bit disappointed that the FW800 - FW400 cable that came with my MOTU kills the extra bandwidth of FW800 devices.

What a crock...

Quote blastmasterd:

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I'd be livid if that was the case...

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Macbook Pro's have always only had one FW bus (but two FW ports).

The beauty of the Pros is that you *can* add a second, independent FW bus with expansion cards. My old Powerbook had a PCI FW card for a second FW bus. I don't have one for my current MBP, because instead I got an eSATA card instead that gives me an eSATA bus which is even faster for drives than FW800.

Of course, the most recent Macbook "Pro" machines, apart from the 17, have removed the expansion card option, which is kind of a bummer...

Quote blastmasterd:

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My MBP just has one FW800 port. I am a bit disappointed that the FW800 - FW400 cable that came with my MOTU kills the extra bandwidth of FW800 devices.

What a crock...

---

If FW800 was important to you, then the best option is to get an FW800 interface, to keep up the bus speed. The bottom line is that laptops are always going to be limited for expansion potential - if you really want a pro setup with lots of top speed expansion options, you need to move to a desktop system.

We all try to push our laptops as far as they will go because they are great machines, but sooner or later, a demanding user is going to feel the limits...

Agreed.

And to be honest, it's not such a big issue that I can't just disconnect the audio interface (FW400) when I want to do some serious copying to the drive.

Great discussion anyway. I wish it was better publicised (or my information searching technique improves)

I suppose it must operate at the lower speed if you have a 400 anywhere in the chain.

If it's 800-400-800 then either of the 400-800 links can only be going at 400. And if it's 800-800-400 then the 800 end must be going at only 400 or else the 400 end wouldn't work.

I suppose.

Well, the point of the thread was to stop the conjecture, and try and work out the *facts*, which haven't really been uncovered.

Your conjecture doesn't solve the initial question of, if you had a FW800 connected to a FW800 computer, with a FW400 device *at the end*, does the *whole* FW chain operate at FW400 (which my conjecture assumed it would) or do the FW800 devices get FW800 speeds, with FW400 only chugging along at FW400 at the end of the chain. In other words, does the FW800 drive in the middle still get FW800, or does it drop to FW400.

Verdict's still out for me.

You're right, I was conjectimafying.

I was presuming that there's a processor of sorts in each bit of FW kit, and that 800 can work at 400 but not vice versa.

Thus, if the processor can only work at 400 or 800 then having a 400 at the end of the chain - as in my second example (I didn't explain it very well, but the "800" at the left is the Mac) must mean that the Mac end is also going at 400 - otherwise the 400 on the end won't be working (unless the two 800 processors, in the Mac and in the middle 800, were very quickly switching between 400 and 800, which would slow everything down I would have thought).

I think the Desmond Hypothesis (it all goes at 400) must be right.

More conjectimafying...

I'm not even sure how things work out on my Mac Pro. It has one 400 and one 800 port at the back, and one 400 and 800 port at the front. Are the two 400 ports on one bus, and the two 800 ports on a different bus, or do they all share the same bus?

I too am in a state of conjectifaction because I am sitting at my PC right now and not my Macbook, but isn't there an option off the About screen for the Mac that gives you a detailed description of the hardware? On this PC the equivalent (Device Manager) tells me there is only one 1394 controller installed, from which I take it that both the FW ports are on the same bus.

If I'm right, then look at the hardware description and count the controllers. If you've got one, they're all on the same bus. If you've got two then it's a pretty safe bet one is 400 and the other 800.

Chris

--------------------
Put the fun back into dysfunctional.
Mr Punch's Studio

Quote ConcertinaChap:

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If I'm right, then look at the hardware description and count the controllers. If you've got one, they're all on the same bus. If you've got two then it's a pretty safe bet one is 400 and the other 800.

Chris

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The information provided is a bit sparse and mysterious:

"FireWire Bus:

Maximum Speed: Up to 800 Mb/sec

Built-in Hub:

Manufacturer: Unknown
Model: Unknown
Maximum Speed: Up to 800 Mb/sec
Connection Speed: Unknown

LaCie d2 Extreme LUN 0:

Manufacturer: LaCie Group SA
Model: 0x0
GUID: 0xD04B7319085C79
Maximum Speed: Up to 800 Mb/sec
Connection Speed: Up to 800 Mb/sec
Sub-units:
LaCie d2 Extreme LUN 0 Unit:
Unit Software Version: 0x10483
Unit Spec ID: 0x609E
Firmware Revision: 0x102
Product Revision Level: V54O
Sub-units:
LaCie d2 Extreme LUN 0 SBP-LUN:
Capacity: 298.09 GB
Removable Media: Yes
BSD Name: disk3
Mac OS 9 Drivers: No
Partition Map Type: APM (Apple Partition Map)
S.M.A.R.T. status: Not Supported
Volumes:
Boot OSX:
Capacity: 128 MB
Writable: Yes
File System: HFS+
BSD Name: disk3s2
Mount Point:

LaCie d2 Extreme LUN 0:

Manufacturer: LaCie Group SA
Model: 0x0
GUID: 0xD04B731A0053F2
Maximum Speed: Up to 800 Mb/sec
Connection Speed: Up to 800 Mb/sec
Sub-units:
LaCie d2 Extreme LUN 0 Unit:
Unit Software Version: 0x10483
Unit Spec ID: 0x609E
Firmware Revision: 0x102
Product Revision Level: V54O
Sub-units:
LaCie d2 Extreme LUN 0 SBP-LUN:
Capacity: 298.09 GB
Removable Media: Yes
BSD Name: disk2
Mac OS 9 Drivers: No
Partition Map Type: APM (Apple Partition Map)
S.M.A.R.T. status: Not Supported
Volumes:
Boot OSX:
Capacity: 128 MB
Writable: Yes
File System: HFS+
BSD Name: disk2s2
Mount Point:

Unknown Device:

Manufacturer: Unknown
Model: Unknown
Maximum Speed: Up to 400 Mb/sec
Connection Speed: Unknown"

It looks as if there's only one FW bus? I'm guessing the "Unknown Device" at the end of the list is a switched-off FW 400 drive.

Quote Tui:

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I'm not even sure how things work out on my Mac Pro. It has one 400 and one 800 port at the back, and one 400 and 800 port at the front. Are the two 400 ports on one bus, and the two 800 ports on a different bus, or do they all share the same bus?

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From Apple's website:-

The Mac Pro computers with Quad-Core Intel Xeon 5400 Series microprocessors were introduced in January 2008. The Mac Pro provides two FireWire 800 IEEE 1394b ports and two FireWire 400 IEEE 1394a ports. The four FireWire ports are on the same FireWire bus and share a single 12V DC-regulated power supply that can provide 18 W per port, for up to 28 W total. If a device is added that exceeds the power limit, the port will be disabled but the other ports will continue to function. Unplug the device, and the disabled port will recover in a short amount of time. FireWire port power is provided when the computer is on, in sleep, or off.

The Open Host Controller Interface (OHCI) connects to the South Bridge IC via a PCI Express 1-lane 2.5 GHz bus. The front and rear FireWire PHYs interface via the OHCI.

The Mac Pro provides front and rear port repeating when the computer is powered on or asleep. Front and rear repeating is also available when the computer is off, unless the computer was shut down from Mac OS X with no FireWire devices connected.

Pretty sure it's the same on the latest generation of Mac Pro.

To follow up on this thread, Metric Halo, notable FW audio interface manufacturers, just posted a FW technote to demystify common firewire myths:

http://www.mhsecure.com/technotes/TechNote_0010/TN_0010.php

Note: ""If I connect a FW400 device to a FW800 bus, it will slow the entire bus down to 400 Mbs." -False

In a mixed speed bus, everything after the slowest device runs at the slower speed."

Interesting...

Quote desmond:

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In a mixed speed bus, everything after the slowest device runs at the slower speed."

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What does it mean? If you connect a FW800 drive to a 800 port, and connect a 400 drive to the 800 drive, will the 800 drive still run at 800?

Did you look at the link? Explains it pretty clearly, I think...

Yes, that's exactly what it means. Keep the FW400 devices at the end of the chain, and the FW800 devices still work at FW800, and the FW400 devices work at FW400 on the same bus.

Any FW800 devices *after* the FW400 device will work at FW400 - so keep the FW800 devices up front, and it should be all good.

Edited by desmond (17/04/10 10:52 PM)

Quote desmond:

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Did you look at the link?

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No. I come here to have it all explained to me.

reading is pretty overrated these days

--------------------
Fostex 812 Mixer -> MOTU 828 mk3 -> MacBook: C2D, 2.4Ghz, 4G RAM, OSX 10.6 || i7 920, 2.66Ghz, 6G RAM, Win 7 Pro -> Reaper v3.6

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