kernel_task process utilizes 100% cpu on mac os x lion

Eariler I had no idea what exactly was going on but then later on after analysing everything I understood that my Kernel_task process wasn’t behaving normally on my Macbook Air 2011. On Wednesday night I was trying to perform a timemachine backup and for that I connected my external hard drive into my Macbook machine. But during that time period I fond something weird, saw that the Kernel_task process was exceeding the normal level of CPU usage. Interstingly I encountered this issue only after I connect the external hard drive. The Kernel_task do not compromise below 100% usage. It is bound to either touch 100% or go beyond this level but never comes down until the external drive is disconnected. Actually most of the time even unplugging the external drive also doesn’t makes any difference, in that case I am forced to hold down the power button which in turns reboot the machine. Just after the system is restarted the Kernel_task process comes down to the normal level.

This is not the first time I am trying to perform a timemachine backup, I have did this task multiple number of time during the initial time when the laptop was newly bought. But now don’t know for what reason I am getting such high CPU usage by the kernel_task process. There’s no doubt that it is the hard drive that starts the issue as the CPU usage rises only after I connect the external drive. However I suspect three things, firstly Lion, then the laptop and lastly the external drive. And as external hard drive play the major role I simply doubt it the most. Researched a lot about this issue on internet but didn’t find any appropriate suggestion that would suite my machine or work for me. Therefore I decided to create a thread myself and look out for some useful and helpful information. So guys, please have a healthy discussion and help out from this issue.

Look as far as I can understand only killing the Kernel_task process can help you out from this issue. Resolving the issue becomes quite complicated and also I do not have any trick of resolving the problem. However bettter you kill the process and if you prefer this then follow my suggestion.

For killing the Kernel_task process you can go to the Activity Monitor then click the runaway process and Exit. However another important thing I would like to suggestion you is that if in case you have any additional partition in your external hard drive that you are having then it would be much better to exclude them from the Time Machine Preferences. I am not sure but I guess the Time Machine preferences already by default considers the external hard disk in the list to Exclude, however if in case, its not in the list then better you do it by following the below direction.
Time Machine > Preferences > Options

Just try out whatever suggestion I gave you and let me know the result. If its working then well and good, and if not working then we see what should be done later.

Hey, I am quite happy to know that I am not the only one with this problem. You wont belive that I have been facing this problem from past 1 month and still now there’s nothing left with me that could help me in resolving the issue. After reading out your thread I can easily make out that your issue is not as advanced as mine. I mean, you are facing the problem only during the time of connecting the external hard drive but my kernel_task process goes above 100% with some of the apple app access like Preview, safari and other applications. However with all the applications the cause of the problem is same i.e. whenever I try to zoom in or zoom out certain things in Preview and if I try a full screen in Safari the app hangs but also the Kernel_task goes upto 100% without any reason.

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Look as far as I can understand only killing the Kernel_task process can help you out from this issue. Resolving the issue becomes quite complicated and also I do not have any trick of resolving the problem.

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Even I was earlier suggested with the same suggestion of killing the process but however killing the process isnt going to solve the problem forever, its just a temporary fix and also killing the process is nowhere a good idea all the time. Better you do not try it out.

Actually you people are in such a big mess that you cant even think to come out of the issue. The place where you are facing the problem is an underlying task and getting it fixed becomes bit impossible sometimes. Connecting an external devices or having a faulty network tends to cause such CPU usage issue. Anyways the best and the reasonable suggestion I would like to give you is disconnect your network(if there’s any)and also make sure that there is no external extra devices like USB drive, hard drive and etc connected to the laptop. I don’t know wheter you will be able to able to get the problem resolved but atlesat you can manage to get down the kernel_task process to the normal level or below the normal level which is better in my opinion. At least you wont have to again and again reboot your laptop in order to get the problem resolved.

I do agree with that, kernel_task process is actually one of the most complicated thing (if caught with any problem then it becomes a huge head ache). Actually the thing is that Kernal_task not just deals with the hardware or the software but it does covers almost everything of your machine including the hardware and software. However coming back to your problem; I have three genuine solutions for you which are somehow meant for such CPU usage trouble so you can try them out without worrying.

Firstly you can try resetting your PRAM and if that do not help you then this time you can go for resetting your SMC. You need not have to worry about the steps, I will definitely help you out with the steps for resetting the PRAM and SMC if you are not well aware of the steps:
For resetting the PRAM follow the following steps:

• Firstly turn off and then start your laptop again. Now press and hold down the following the keys of your keyboard altogher: Command, Option, P, and R
• It would be much better if you check out these keys before you perform to hold them together because you are actually suppose to hold down the keys simultaneously.
• While your machine is starting, before you see the gray sceen you are supposed to hold those above mentioned as according to the insctruction
• Do not release the keys until and unless you hear a startup beep or sound for the second time, allow the machine to restart completely. As you hear the sound leave the keys. By doing so your PRAM and NVRAM are however set in your computer, that too with the default values.

Now for resetting the SMC you can do the following direction. Here you have to be alert while removing the battery so better be careful.

• Firstly turn off and the disconnect the power adapter of your laptop. After everything is removed now you need to remove the battery
• Now press and then hold down the power button for few seconds (atleast for 5 to 10 seconds)