# iMac won't start with USB hard drive plugged in...



## Rubble (Mar 4, 2007)

iMac 2.7 GHz i5, 8GB ram 1TB hard drive. OS X 10.6.8

I bought a 1TB Verbatim usb 3.0/2.0 portable drive to use for Time Machine back ups. Desk space is a very real issue at the moment, thus the very small footprint required. I formatted it with one partition OS X Extended (Journaled) GUID partition table. I did a full back up with no problem. The drive is plugged straight into the computer, no hub

This morning when I turned on the computer, just a grey screen for 10 minutes. I unplugged the portable drive and everything starts as normal. I checked all the settings: Start Disk etc. and everything seems to be pointing to the internal drive for start up, but every time I try to boot the thing (I've tried about 8 times today) with the Verbatim plugged in - nothing.

I have a powered firewire drive (in storage 1800 km away at the moment) that doesn't cause any problems.

Any suggestions?


Thanks,


Rub


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## Jim (Jan 31, 2003)

Have you tried using Disk Utility to rebuild permissions on internal drive and usb external drive after startup and after connecting usb drive? I would also take a shot by rebuilding pram by depression Command, Option, P, M keys during startup.


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## jamesB (Jan 28, 2007)

I have the very same external Verbatim drive you speak of, and I experienced the same symptoms.
This occurs not only with Lion but also with Snow Leopard, at least for me, and makes the drive useless for SuperDuper clones as I cannot boot from it.
I have not tried this but maybe using a powered hub between the drive and computer just might enable it to be recognized at boot up, this 1GB drive is really pushing the limit for a USB only powered drive.


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## Rubble (Mar 4, 2007)

jamesB said:


> I have the very same external Verbatim drive you speak of, and I experienced the same symptoms.
> This occurs not only with Lion but also with Snow Leopard, at least for me, and makes the drive useless for SuperDuper clones as I cannot boot from it.
> I have not tried this but maybe using a powered hub between the drive and computer just might enable it to be recognized at boot up, this 1GB drive is really pushing the limit for a USB only powered drive.


Well that's interestingly frustrating... No powered hub to be had for at least a month when I'm back to civilization. For the time being I'll just have to remember to unplug it before I turn things back on. I guess it's just another component that will end up gathering dust in a dark closet...

Rub


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## SINC (Feb 16, 2001)

I returned a Verbatim for exactly the same issue only on a 13" MacBook Pro. Got an Iomega for $30 more and no further issues.


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## jamesB (Jan 28, 2007)

unfortunately I never realized the problem until any hope of a return was long past.
What I ended up doing was popping the case open and replacing the drive with a 500MB unit which does work as needed, I think due to less startup current required.
The 1GB verbatim drive now sees service in an OWC FW800 dock.


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## pm-r (May 17, 2009)

Will it work if unplugged at boot, then connect it when booted?? It sounds like it does.


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## jamesB (Jan 28, 2007)

pm-r said:


> Will it work if unplugged at boot, then connect it when booted?? It sounds like it does.


Yes mine did, that's how I managed to get the system cloned using SuperDuper.
Problem only reared its ugly head on reboot, then nada, just a white screen.


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## pm-r (May 17, 2009)

Does it have any provision to accept an external power adapter or maybe your suggestion to try using a USB powered hub would work. I picked up a small Belkin powered hub for about $20.00± a while ago, so there're cheap.

Otherwise a bummer for a bootable backup drive that can't be utilized properly, and good to know they might be a unit not to be recommended.

I'm not sure of which exact model you have from the Verbatim's product list.


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## jamesB (Jan 28, 2007)

This one...

This is also a 12mm thick drive, I think due to an extra platter, hence the higher startup current draw.


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## MacDoc (Nov 3, 2001)

You can grab a dual USB cable that should solve the problem ...low USB power is problematic....careful on the Airs as well - they appear more prone to that and of course we all want the lightest back up solution


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## krs (Mar 18, 2005)

Rubble is trying to boot up using the *internal* drive of the iMac, he's not trying to boot up with the *external* Verbatim drive.
Why should the external USB drive, even if it draws more than the 500 ma current allowed from a USB port, prevent the Mac booting up normally from an internal drive.

I have had my share of USB powered externals that won't mount because of power issues, but none ever prevented my Mac to boot up.
But then I never owned an iMac.


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## jamesB (Jan 28, 2007)

krs said:


> I have had my share of USB powered externals that won't mount because of power issues, but none ever prevented my Mac to boot up.
> But then I never owned an iMac.


The problem s not related to only iMacs, the verbatim 1TB drive I had would prevent either my MBP or 2009 Mini from booting.
In both case the drive would mount and be usable if plugged in after a normal boot from the internal drive.


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## jamesB (Jan 28, 2007)

MacDoc said:


> You can grab a dual USB cable that should solve the problem ...low USB power is problematic....careful on the Airs as well - they appear more prone to that and of course we all want the lightest back up solution


Something like this might help someone, but on my pre-inibody MBP the USB ports on opposite sides.
Note the USB 3 connector.








A totally new and proven to work brand of drive appears to be a better solution.


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## krs (Mar 18, 2005)

jamesB said:


> The problem s not related to only iMacs, the verbatim 1TB drive I had would prevent either my MBP or 2009 Mini from booting.
> In both case the drive would mount and be usable if plugged in after a normal boot from the internal drive.


Do you know what the current draw is?
I can't find that information anywhere.
Or which hard drive is inside the enclosure.

I still find it surprising that this external draws so much current on start up that the Mac won't start up on its internal drive.

I just bought a plain 1 TB WD 2.5-inch drive for $60.- to be mounted into an enclosure I already have.
It uses two platters, max. current draw is spec's at 0.55 amps.
A bit over the limit but I hope it will mount using just USA power without special cables or powered hubs.


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## pm-r (May 17, 2009)

jamesB said:


> Something like this might help someone, but on my pre-inibody MBP the USB ports on opposite sides.
> Note the USB 3 connector.
> View attachment 21278
> 
> ...


Many with the alternative USB ports on the opposite sides have just used a short USB extension cable if any extra power was required and the supplied Y adapter was too short to connect. 

Have you tried such a USB connection and powered method?? Such cables are cheap enough to at least try.


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## Rubble (Mar 4, 2007)

FWIW the drive shows up in Disk Utility as:

TOSHIBA MK1059GSM Media

Rub


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## krs (Mar 18, 2005)

Rubble said:


> FWIW the drive shows up in Disk Utility as:
> 
> TOSHIBA MK1059GSM Media
> 
> Rub


Thanks,

Yes, power requirement is definitely an issue - rated at 1 amp at 5 volts


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## jamesB (Jan 28, 2007)

pm-r said:


> Many with the alternative USB ports on the opposite sides have just used a short USB extension cable if any extra power was required and the supplied Y adapter was too short to connect.
> 
> Have you tried such a USB connection and powered method?? Such cables are cheap enough to at least try.


I'm no longer interested, having solved my problem as I posted back in post #6.


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## jamesB (Jan 28, 2007)

krs said:


> Thanks,
> Yes, power requirement is definitely an issue - rated at 1 amp at 5 volts


I suspect a USB 3 port supplies more power then USB 2, but they still market these drives as being USB 2 compatible.


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## pm-r (May 17, 2009)

jamesB said:


> I'm no longer interested, having solved my problem as I posted back in post #6.


I guess I missed your #6 04:25 PM post when I replied and questioned Yesterday, at 04:31 PM with post #7.

Just like silent ships passing in the night.


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## krs (Mar 18, 2005)

jamesB said:


> I suspect a USB 3 port supplies more power then USB 2, but they still market these drives as being USB 2 compatible.


You're right - quite a bit more........



> A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. There are two types of devices: low-power and high-power. A low-power device draws at most 1 unit load, with minimum operating voltage of 4.4 V in USB 2.0, and 4 V in USB 3.0. A high-power device draws the maximum number of unit loads permitted by the standard.


..........1 amp is even outside the USB 3.0 spec

I would certainly understand if that external didn't mount or if you can't boot from it - but preventing the Mac from booting up on its internal drive ???


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## eMacMan (Nov 27, 2006)

krs said:


> You're right - quite a bit more........
> 
> 
> 
> ...


I can recall more than one USB creating havoc up to and including boot failures. Since it is an iMac go with the powered hub and maybe even a Y-connection to the hub. 

Otherwise consider going with a powered enclosure.


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## Rubble (Mar 4, 2007)

Excellent stuff, thanks. First opportunity to get a powered hub, I'll do it. I'll probably get the Y cable as well and report the results.

Ryb


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## Rubble (Mar 4, 2007)

The powered hub didn't work. Still no starting even with it juiced up. I couldn't find a USB3 'Y' cable but won't even go any further with this... Might be able to pawn the drive off (read that as give it) to my brother who only does Windows... 



Rub


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## krs (Mar 18, 2005)

A powered USB hub that meets the USB spec won't help - you still need the Y-cable.
Only benefit there is that you only use one USB port on the Mac.

But simply - a powered USB 2.0 port is supposed to provide 500ma of current at 5 volts (a USB 3.0 port will provide substantially more, close to an amp I think).
Some of the cheaper USB 2.0 hubs (and ports on PCs) don't have the 500ma currentlimit built in so they will provide a bit more current but still not enough to drive.
I see I already explained that in post 22 above.

Anyway, with a Y-cable you combine the current provided by two USB 2.0 ports, 500ma eachto give you 1 amp and that should work.

Windows in that respect is no different although there are PCs that provide current on one particular USB 2.0 port way outside the USB soec.
I have a Dell Notebook and I think one of its USB ports is rated at 1 amp.
So ironically - products that are designed to meet the USB spec will not work and others that do not meet the USB spec might actually work.


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## pm-r (May 17, 2009)

Rubble said:


> The powered hub didn't work. Still no starting even with it juiced up. I couldn't find a USB3 'Y' cable but won't even go any further with this... Might be able to pawn the drive off (read that as give it) to my brother who only does Windows...
> Rub


A standard USB Y-Cable should fix the problem whether used with the Mac or the powered hub and should be readily available for about $10.00±.

I the Mac is a portable with the USB ports on opposite sids, you'll need a USB extension cable to use the USB Y Cable as their cables usually aren't long enough.


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## monokitty (Jan 26, 2002)

The solution is to use quality drives that aren't crap.

/blunttruth.


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## pm-r (May 17, 2009)

Lars said:


> The solution is to use quality drives that aren't crap.
> 
> /blunttruth.


You mean like _*some*_ of the Lacie and other well known 1TB USB drives that forget or don't include any USB Y Cable and also fail to power up??


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## monokitty (Jan 26, 2002)

pm-r said:


> You mean like _*some*_ of the Lacie and other well known 1TB USB drives that forget or don't include any USB Y Cable and also fail to power up??


I mean get a quality FW400/800 drive which won't give you this issue in the first place.


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## pm-r (May 17, 2009)

Lars said:


> I mean get a quality FW400/800 drive which won't give you this issue in the first place.


Now that's a comment that I'll agree with 100%!!!!

For a few $ more = faster, better, more reliable and very few hassles.

OT a bit, but I was surprised by a Samsung USB CD/DVD drive I got for a fellows original MB Core Duo to "replace" its virtually dead internal optical drive, and only a single USB power connection was needed with the supplied USB Y Cable for it to work properly.

Amazing that some of the 1TB and over USB hard drives seem to require more power than a USB optical drive reader and burner to work properly.


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## Rubble (Mar 4, 2007)

Lars said:


> I mean get a quality FW400/800 drive which won't give you this issue in the first place.


Not all of us have the resources at our finger tips to go out and buy a FW drive off the shelf. And some of us don't have the luxury of being able to have things couriered or mailed to us when we shop from the web, so we make do with what is available and try to find a work around solution. The reason I tried what I did with the USB drive was the need to back things up and some very rare time on my hands. If I was in a place where other options were available I would have gone a different route. So here it is some 4 weeks since I bought the drive and I just now managed to (sort of) reach a solution:

While off work I was able to visit my favourite Apple Reseller and was talked into a MacAlly FW800 box. I pulled the original enclosure apart and pulled out the drive. Plugged everything together and it all worked exactly as I had hoped it would in the first place. The iMac boots with it plugged in and it backs things up really fast, with that I'm happy. 

Here's the new problem: The drive is too tall and I can't put the enclosure cover on. It's not much, maybe 1/32". And because the enclosure is extruded aluminum I can't force the drive in by bending the top up enough... not sure what the next step is... Won't be visiting my dealer - or any others for that matter - for another two months. At least it is working even though it is sitting naked on my desk.

Rub


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## krs (Mar 18, 2005)

Lars said:


> I mean get a quality FW400/800 drive which won't give you this issue in the first place.


Portable firewire drives can have their own problems as I found out the hard way - even "quality" ones.
Although a FW port provides plenty of current for a 2.5-inch laptop drive, all of those 2.5-inch FW enclosures are not designed to actually use the FW port for power.
Talking to the manufacturer, the basic problem seems to be cost - FW provides 15 volts at the port whereas the 2.5 inch drive requires 5 volts.
So the enclosure needs a DC-to-DC converter to allow the FW port to power the laptop drive. Easy way out is to use the 5 volt USB port to power the drive and use the FW port just for the signal transfer. Something that is not spelled out in the literature either - there it just says "bus powered".


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