Bus power while sleeping on mid-2012 15" MacBook Pro?

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Bus power while sleeping on mid-2012 15" MacBook Pro?

I have an external hard drive connected to the Firewire 800 port with a FW800-FW800 cable. It is bus-powered. On my previous Mac, a mid-2009 13" MacBook Pro, the drive would remain powered while the computer was asleep - it would spin down, but the lights on the drive would remain on, and it would spin up again when the computer woke up. Perfect. But my mid-2012 15" MacBook Pro cuts off bus power in sleep mode, so the drive no longer wakes up with the computer. Both are running OS X 10.8.3.

The FireWire Ports: Specifications KB article says, "Output power is always available if the Apple computer is connected to AC power or is running (even on battery). Output power can be used to power FireWire hubs and devices such as disk drives and audio break-out boxes that operate within the limits of the computer’s FireWire port." I don't know whether "always available" includes sleep mode.

The reason this is a problem is because when I wake up the computer, the drive remains off, so any applications that had open files from that drive get confused, changes lost, etc. Basically, it's a disturbance.

I have tried resetting the NVRAM and SMC on the newer MBP, but it didn't change this behavior.

MacBook Pro, OS X Mountain Lion (10.8.3)

Posted on May 19, 2013 7:39 AM

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Answer 1

Jun 4, 2013 7:06 PM in response to alexant

Same thing has been happening to me since I upgraded to ML, just with my FW800 audio interface.

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Answer 2

Jun 4, 2013 7:20 PM in response to alexant

I disagree with your reading of that article:

"Output power is always available if:

[a] the Apple computer is connected to AC power or

[b] is running (even on battery)."

Sleeping is not Running.

I see no guarantee that you will continue to have power while sleeping on battery. I think you will need to leave the power adapter connected at all times, or use an external power source for the external devices if you want to allow the computer to sleep, and expect the external devices to have power during sleeping.

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Answer 3

Jun 4, 2013 7:42 PM in response to Grant Bennet-Alder

Thing is, at least I experience a very similar issue (as have many others) with AC Power. The OP doesn't really state whether on battery or AC power.

I had my 2011 MBP for over 2 years and my MOTU Ultralite audio interface for the same period. For the entire 2 years, my MOTU would be conneceted via FW800 and bus-powered. It would not lose power when my computer went to sleep (default Snow Leopard settings, going more than 24 hours without being touched). A few months ago, a new piece of software asked me to upgrade to Mountain Lion and, since that upgrade, I've had problems with my MOTU losing power when connected via FW800, all while connected to AC power... for no good reason.

At least while on AC power, I would think "always available" means always available regardless of sleep mode.

Like the OP, I have not had succes with NVRAM or SMC resets.

In browsing other threads, I see that some have had some success resetting permissions.

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Answer 4

Jun 5, 2013 6:02 PM in response to alexant

OK - it looks like I may have solved the issue... its at least not cutting bus-power to the MOTU anymore. This is what I did:

1. Entered disk utility

2. Repaired disk

3. Repaired permissions

4. Rebooted

5. Set energy settings to sleep computer after 1 minute.

6. Left computer alone with MOTU on for 45 minutes

7. MOTU remains on, computer wakes up no problems

Not sure how permanent this is, but it is working so far.

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Answer 5

Jun 5, 2013 8:38 PM in response to alexant

Nevermind - it was working for a bit and now it doesn't.

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