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I use a MyBook 1Tb FW800 drive from Western Digital as my Time Machine backup, and I also have a FW800 Lexar CompactFlash card reader. My 2011 MacBook Pro only has one FW800 port so I have to daisy-chain the two devices, which both have 2 FW800 ports each.

However it seems to matter in which order I connect the items together. If I connect the drive to the Mac, then the card reader to the drive, the card reader might not show up, or the drive may dismount; I've not really had the time to tabulate all the possible permutations of chain order and port use. Are issues like this common with FW800, and is there some way I can resolve them?

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An obvious, but worthwhile suggestion to make - Check you've got the latest updates and make sure your Mac's firmware is at the latest revision. – macaco Dec 12 '11 at 9:17
Thanks - everything is up to date. I'm fastidious to the point of OCD about this :) – Nick Miners Dec 12 '11 at 9:48

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Firewire attempts to use "smart" daisy chaining, which permits links in the daisy chain to be off. Unfortunately, that doesn't always work effectively. Apple recommends you first plug the device into the Macintosh, wait for it to become visible, and then add devices one at a time. 1

As for particular details with regards to your problem, I've had issues with card readers in which they either didn't really truly meet the firewire spec and therefore were unhappy with daisy chaining, or they would attempt to "smart" turn-off when a card was not in them, which caused it to also disable other parts of the chain.

In short, daisy chaining with Firewire is great, except when it isn't. YMMV.

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Many thanks for the information. That KB article is really useful. – Nick Miners Dec 14 '11 at 21:32

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