Desk Utility with Ext. Hard Drive

[Sam165]

Hi Bryan!  I have been using CleanMyMac X since you advised.  Everything great except something with my one ehd.  So I went to disk utility and First Aid on my iMac.  It says "First Aid process failed.  Unable to unmount volume for repair."   What does this mean?

Thanks!

[Brian]

The MacOS is based on a operating system called Unix (pronounced you-nicks) that dates from the 1970’s. In order to do a file systems check on a HD, it needs to be unmounted first. A Mac computer does not differentiate between a internal hd or external one. That’s why you do not want to go more than 75%-80% full on any HD, internal or external. 

Before we get into running First Aid and why it couldn’t un-mount, why are you running First Aid? Second, how is this external HD partitioned? Is it the stupid exFAT or is it the MacOS Extended (Journaled). Let me know. 

[Sam165]

Hi Brian, I thought I'd check in and found an old post that is applicable to me today.  This same thing happened today on an ehd.  I was doing a First Aid because in Clean My Mac, it failed to check this hard drive.  It is MacOS Extended (Journaled).  I am not sure if this is the same ehd as in April but thought I'd better contact you.  Thanks 

[Sam165]

Hi Brian,

So I just ejected the ehd, shut down computer, re-started computer.  Ehd was then checked with First Aid and all was good.  Guess turning off computer works again