Time Machine sometimes unmounts

gogreen1

macrumors regular
Original poster
Nov 20, 2017
194
11
Why does Time Machine occasionally unmount from my iMac after startup, and how can I prevent that? "Get Info" shows that on its 1.2 TB drive, Time Machine has used 515 GB out of an available 684--does that have something to do with it? I can go into Disk Utility and re-mount it. Still, why does it unmount and how do I prevent that?
 

Ruggy

macrumors 6502
Jan 11, 2017
252
154
Very difficult to say but I have best luck with the ones that I have bought as external drives rather than the ones where I've bought a hard drive and put it in an external box- I don't know if that rings any bells?
I have a Western digital one that has never once unmounted unexpectedly for instance, all the ones I've made do.
I personally think it's something down to the controllers.
Someone else will probably have more knowledge and insight on this than me but that is my experience.
 

gogreen1

macrumors regular
Original poster
Nov 20, 2017
194
11
Thanks, HDFan and Ruggy.

I get no error message that the disk ejected. To be clear, I partitioned a Western Digital 2T My Passport into three parts, one of which is for TimeMachine. The other partition icons appear as drives on my desktop with no problems. The TimeMachine icon occasionally disappears shortly after startup.

Could the partition's being so full have anything to do with its disappearing (even though TimeMachine automatically takes care of that)?
 

HDFan

macrumors 68000
Jun 30, 2007
1,508
367
The TimeMachine icon occasionally disappears shortly after startup.
Do you mean the icon for the TM disk drive partition disappears from the desktop and from the Finder side menu? If you go into disk utility do you see the 3 partitions? Does the TM partition show? Is it mounted? If not can you mount it?

Could the partition's being so full have anything to do with its disappearing
Shouldn't. When TM runs out of space it deletes old backups to free up space.
 
Last edited:

gogreen1

macrumors regular
Original poster
Nov 20, 2017
194
11
Yes--the icon for the TM disk drive partition disappears from the desktop and from the Finder side menu.

Next time this happens, I will go into disk utility and see if the 3 partitions are there, and if TM isn't there, if it's still listed. If it's listed, I can probably remount it. Thanks.
 

gogreen1

macrumors regular
Original poster
Nov 20, 2017
194
11
Finally it misbehaved. In addition to TM's disk partition disappearing from the desktop and from the side menu, disk utility does show the TM partition as part of my My Passport, but the TM partition is gray. I pressed "mount," and the icon reappeared on the desktop. That's an easy fix, but why does this happen?