HD intermittently mounts/unmounts

[nyroger]

I have a HD that intermittently mounts/dismounts without any input from me. My setup is as follows: HD #1 is the problem HD; it is connected to iMac via Thunderbolt/firewire adapter. HD #2 is daisy chained to #1 via firewire 800/400 cable. Equipment is late 2013 iMac with Maverick OS.

As stated above HD #1 will mount on the desktop and then without any input from me it will suddenly dismount. Later it will suddenly mount again. This activity continues to repeat over and over. I have no problems with HD #2. Thanks for your help.

 

[Bear]

Is the problem disk FW powered or does it have it's own power supply?

 

[chabig]

My Thunderbolt drives do that occasionally. I shut down, reseat the plugs, and reboot. That usually clears it up.

 

[nyroger]

HD intermittently mounts/unmounts

HD is powered by 110v.

 

[martinm0]

HD is powered by 110v.

Is the second drive powered by its own plug, or is it powered by the first drive? If it's powered by the first drive, try disconnecting the second drive for a while and see if the mounting issue is resolved. Possibly the second drive is somehow getting the bulk of the power over the first drive??