External HDD Eject = OK, but Unplug after = Kernel Panic?

[jman995x]

I have an iMac which I have a 6TB WD External HDD attached to.

I've never had a problem in the past with ejecting the HDD, then unplugging it (so that it's not running the disks for hours when I'm not using it).
However, the last couple of days when I eject the HDD, when I go to unplug it, my iMac has a kernel panic and restarts (with the grey screen and the restart message in multiple languages).

I've not only closed any program that was using the External HDD before ejecting it, but I've also gone so far as to open up Disk Utility, click on the main icon for the drive (even though the Named icon is greyed out, denoting it's been ejected, but is still connected), then clicked the eject button. But, to no avail....

Any ideas why something I've done the exact same way for the past 2 years is now causing a kernel panic / restart?

Thanks,

J.

 

[TattooedMac]

I could be something as simple as a cord issue. Kernel Panic usually happens, when there is a Hardware issue, so if you have other cords, try them out, and while in Disk Utility, Verify Disk on the 6TB External. If that HD is going south, then it should show up, and if it is, repair it, Verify Again, and if it still shows up Red, then you might have a failing Ext HD.

 

[MacInWin]

And, btw, the most stress on a drive is during power on and off, so if you are trying to avoid a drive failure by unplugging it, you're probably actually making it more likely to fail. I leave all my externals spinning 24/7, and have done so for years.

 

[TattooedMac]

And, btw, the most stress on a drive is during power on and off, so if you are trying to avoid a drive failure by unplugging it, you're probably actually making it more likely to fail. I leave all my externals spinning 24/7, and have done so for years.

Yes, this is a good point. I have mine the same, and usually, if you have the settings in System Prefernces>Energy Saver>Power Adapter; and checkmark Put Hard Disks to sleep when possible, the Ext HHD, should sleep at some stage as well.
Even Still, i have my iTunes Library on a Lacie Porsche 4TB Ext HD, and even when im streaming to my ATV, and it is finished buffering the hole show, it sleeps, and when i click to watch the next show, it whirrs up, and wakes to stream the next show to the ATV.

 

[MacInWin]

I have not allowed Put Hard Disks to Sleep, again because the startup and shutdown is the hardest thing for the drive. I just leave them spinning and keep the temps well inside the boundaries. I used to manage major data centers and the drives in those placed run 24/7/365, so the drives can take the running. It was the odd occasion when a drive array needed to be powered off and back on that "killed" the drives. I always sweated the on/off cycle.

 

[IWT]

I have not allowed Put Hard Disks to Sleep, again because the startup and shutdown is the hardest thing for the drive. I just leave them spinning and keep the temps well inside the boundaries. I used to manage major data centers and the drives in those placed run 24/7/365, so the drives can take the running. It was the odd occasion when a drive array needed to be powered off and back on that "killed" the drives. I always sweated the on/off cycle.

Hi Jake

We have joined others in discussing this on other threads, but just to be clear, for my benefit:

Are you advising that the iMac HD, my TM EHD and my "weekly BU EHD" should all be left spinning and that I should only put the display to sleep?

My practice, till now, has been to put the iMac HD and the TM EHD to sleep after 45 minutes (but not shut them down in the sense of stop/eject/power off). My "weekly BU EHD", I have unmounted after each weekly BU.

I am genuinely interested in your opinion on this as it will alter my practice. I had assumed that "sleep mode" slowed things down "gently" and spun up again "gently" thus minimising wear. So guide me please, if you have the time.

Ian

 

[MacInWin]

Ian, there is no "gently" in start/stop for an electrical motor. If the drive is "asleep" the drive is not spinning, the circuitry that monitors the spinning is not powered, the only thing drawing power is the circuitry that responds to the demand from the interface for data. When you call for data, the drive applies power to the motor to start the drive spinning and to the heads to start them moving to read the drive (that's another motor, in a different form). In that process there is an inrush of current to the various components that are involved in that process. Most electronics failures occur at that inrush. Now, if you don't power up/down every day, but only once a week, you expose your devices to that inrush a lot less frequently than someone who uses them daily. I cannot and will not make any specific recommendations to you on how to manage your device, it is really up to you, but you need to know that the most likely time of failure is when that motor is going from stopped to spinning. For me, I backup every day, so I just leave the backup drives attached and spinning.

BTW, the display has the same inrush problem, but in that case the risk of inrush is balanced by the fact that the backlight has a lifetime measured in hours lit up, typically, which means that it's generally better to let the display sleep. In addition, the display is the single biggest draw of power in the computer, so you save the maximum energy with it blacked out. But the power on/off or backlight on/off is still the most likely time of failure.

The same logic applies to light bulbs and every electrical appliance. It's just a fact of life that the time an electric device is most stressed is at power on/off.

Here is a Wikipedia article on inrush current: Inrush

 

[IWT]

Jake

A clear, concise and extremely helpful summary which I very much appreciate. I will not be the only one to benefit.

My grateful thanks.

Ian

 

[TattooedMac]

I have not allowed Put Hard Disks to Sleep, again because the startup and shutdown is the hardest thing for the drive.

On closer look, either have I, and have I ever. My Lacie, sleeps all by itself, and has nothing to do with the Mac it is connected too.

 

[Rod]

So how does this practice apply to a MBP. I dont have "Put HD's To Sleep" enabled on my laptop but obvoiusly i unplug my external HD on a regular basis.

 

[MacInWin]

On closer look, either have I, and have I ever. My Lacie, sleeps all by itself, and has nothing to do with the Mac it is connected too.

Yes, some manufacturers build it in. I don't buy those drives. Seagate is (in)famous for that. Seagate's sleep is so aggressive that in my system OS X actually sees the sleeping drive as unmounted and sent me complaining messages about it. I got rid of all Seagates. My one LaCie doesn't sleep.

So how does this practice apply to a MBP. I dont have "Put HD's To Sleep" enabled on my laptop but obvoiusly i unplug my external HD on a regular basis.

I have a MBP and I don't shut down the externals. I leave the MBP running pretty much all the time. Essentially it's a desktop that occasionally gets to travel. When I do travel I tend to be gone for weeks, so I take two portable EHDs with me for backup--the one with TM backups and the one with CCC backups on it. They do get powered up each evening for backups and storage of the camera contents for the day.

Don't worry too much about this. It's more an academic exercise than anything else. I was responding to jman995x comment:

I've never had a problem in the past with ejecting the HDD, then unplugging it (so that it's not running the disks for hours when I'm not using it).

My whole point was that letting disk run for hours is not hard on the drive (and frankly, the energy it takes is also very small), and that the actual stress on the drive is power on and off. Then when Ian talked about "gently" starting I got all academic. No need to panic, do what you need/want to do. About the only thing to avoid is stopping drives and powering off multiple times every day to the point of actually abusing the drive.

 

[Rod]

I have a SeaGate iTb drive I use for backups and a Transcend 500Gb both of which sleep when not in use. Neither unmount when asleep but I notice my wife's WD Passport 1Tb CCC backup never sleeps and yet it is the only one of the three that has required replacement due to failure in 5 years.;P

 

[johnodd4]

Ok I can help you there.

It's not because the drive is going to sleep it is because when mac os x maverick and yosemite are accessing the drive the o.s itself no applications the drive will display a error message because when you go to eject the drive the o.s is still using it not the application