Running OS on external hard drive - shutdown and drive safety

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Hello,

I have successfully installed and running OSX Yosemite Beta on a portable external usb hard drive. It runs ok but takes a long time to boot up - probably due to running off usb.

However my question is about the safety of the actual hard drive when you shutdown the computer. Obviously the computer switches off and the power goes off forcing the usb powered hard drive to stop. Is this bad for the hard drive? If so is there anything I can do to prevent this type of wear or possible damage to the drive?

Obviously the normal alternative is to create a partition on the main computer hard drive, however I do not have enough free space to do this and also play around with my current programs and files.

I hope what I am currently doing is not bad for the hard drive.
Thanks.
 
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However my question is about the safety of the actual hard drive when you shutdown the computer. Obviously the computer switches off and the power goes off forcing the usb powered hard drive to stop. Is this bad for the hard drive? If so is there anything I can do to prevent this type of wear or possible damage to the drive?

If you were booting off an internal drive, shutting the computer down would "force" the internal drive to stop also. You have nothing to worry about here.
 

vansmith

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Apple has instructions on their KB for installing OS X to an external disk (source) so I wouldn't worry that it would be doing any more damage to your hard drive than it would to any other disk.
 
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Thanks for the replies.

I thought maybe the internal drive might be prompted to switch off before the computer actually powers off, allowing the read/write head to safely park itself before the power is cut.

I know when I "eject" an external hard drive you can hear it slowly wind down, however when you turn the computer off with the drive attached it seems more sudden.
 
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Thanks for the replies.

I thought maybe the internal drive might be prompted to switch off before the computer actually powers off, allowing the read/write head to safely park itself before the power is cut.

I know when I "eject" an external hard drive you can hear it slowly wind down, however when you turn the computer off with the drive attached it seems more sudden.

Modern drives have safety features that park the head when power is lost, so there's no worry. The only scenario where this could possibly still be a problem is if data is being written to the drive as power is lost. Even that's still a pretty remote chance. None of this should be an issue here since you are booted off that drive and doing a proper shutdown.

If you are still really worried about this, just stop using an external drive to boot the computer.
 

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