Hello everyone,
This reply really goes out to all of you in case it applies to your situation, not just Leanne73. I realize that there are any number of confounding variables [cable integrity, hardware compatibility, software compatibility, etc.], but I managed to find a fix for me and it was such a relief that I'm sharing it wherever I find people talking about connection issues with random/unexplained ejections.
Anyway, my hard drive [I have a 4 TB Seagate external hard drive with USB 3.0 that I'm using with a Mac OSX Yosemite version 10.10.2. The drive was originally formatted for windows - it was much less expensive than the mac version - and I reformatted it for Mac] was also having connection issues, like randomly ejecting itself after being connected for only a few minutes, twenty minutes, an hour if I was lucky.
When I first got my hard drive, it didn't have issues and worked fine. Then there were issues with hibernation/sleep, so I turned those off in my preferences and it seemed to fix the problem - until I updated my software. I was getting all the same symptoms - random ejections, intermittent connection, or sometimes the drive wouldn't read at all. I tried all manner of basic troubleshooting, like rebooting with the drive plugged in [USB], rebooting with drive unplugged [USB], changing settings in system preferences with energy saver, but nothing was conclusive to solving my problem.
In a different thread titled "External Hard Drive Randomly Ejects From Macbook Pro - "The Disk Was Not Ejected Properly," user AxEffects posted this comment on page 4 August 16th, 2013[the portion with the steps that solved my problem about midway down is bold and italicized]:
"Hi there folks,
While surfing the mac forums lately I've seen a lot of people having difficulties with external storage devices not being detected, and many, being dismounted or self-ejecting causing loss or damage of data. I've also read of problems pertaining to old data not being accessible on the new drive. This being said, I've had these same issues recently with my Mac. Take a deep breath, all is well. It really isn't your Mac. After reading so many forum posts I've decided to share some of my experiences that have answered questions and resolved these problems for me.
Here are some solutions for most of the folks I'm sure, who are having problems with self-dismount/eject:
I'm running a 2013 Macbook Pro Retina with OSX 10.8.4 Mountain Lion.
For those that just can't get their drives recognized or to show in 'Finder':
I'll start with proper formatting. Be sure your new drive has been formatted as 'Mac OS Extended (journaled)' and that the partition map scheme is 'GUID Partition Table.' Even though your drive should have come formatted for your Mac 'out of the box', sometimes they just don't get it right.
An important factor worth mentioning is to be sure you're running your external storage device with the most recent firmware. Just because that shiny new drive came fresh out of the factory sealed box, doesn't mean you have the latest firmware. Keeping your firmware up to date is a most definite necessity as each and every day brings us new features and function in our operating systems, that sometimes changes how hardware will behave and does indeed require Firmware Updates from the manufacturers.
Ensure your USB/Firewire/Thunderbolt connections are functioning properly; this is especially important if you are using an expandable multi-port hub with your system. Via 'System Report' pull up 'Hardware' and 'USB', 'Firewire', 'Thunderbolt' (whichever applies). Look at the data and be certain everything is being found, and found correctly. If you see something that is not being found, or is being found incorrectly (USB 3.0 connection being found as a USB 2.0 as an example) be certain of a couple of things:
Check that your power for all of your devices are connected (external drive power, power for your hub, etc). You may have been using your hub passively running other low consumption devices on it with line level voltage from your computer with no problems. However, your hub must have power to run a device of this type. Another possibility is that your cable may be damaged, or you're plugged into a USB hub or USB port on your computer that only supports USB 2.0.
For everyone who suffers with "improper eject":
The first thing I discovered when I had problems with other external drives dismounting is that power management in newer Macs use a VERY LOW POWER sleep mode, almost to hibernation levels. Most external drives can only detect a connection to a computer when the computer is sending a line level signal via connection cable. When newer macs enter sleep mode the power is beneath the threshold level the external devices are capable of sensing. Therefore, when the computer sleeps, the drive thinks the computer is off and puts itself to sleep causing improper dismount or self-eject, and of course generating the message that the device has been improperly ejected. Yes, this can damage files. What is required when using these devices, is to either eject the drive manually through the Finder Window, and then let your computer sleep at will, or adjust your power management setting in the "Energy Saver" tab to "NEVER" for the 'Computer Sleep' setting. Also in the same Energy Saver window, be certain to UNCHECK 'Put hard disks to sleep whenever possible," and UNCHECK 'Enable Power Nap.'
Many external drives have there own power management features as well, that can be set from its own settings window and these operate independently of OSX. If these devices are set for a sleep mode before OSX sleeps, it will cause itself to eject improperly from the OS and you will get error messages and possibly corrupt data, and, or your back up. Where these devices offer power management settings, it is advisable to disable any sleep settings. Until all of the manufacturers catch up with ultra low power connection discovery, it is highly recommended that you manually eject your drive through OSX Finder prior to any time you plan to let your computer sleep, or before you turn it off. This should be rule of thumb for any external storage device connected to a Mac. I personally leave my computer on full time during the day with external drives ready at the helm. I have had ZERO issues since discovering these things.
This said, some users will have their external drives plugged into a power strip separate from their computer; and I know people who do this; they will turn off the power strip when shutting down the computer; the computer may not be ready and when the power to the drive is shut down...voila, improper eject.
Another item that contributes to these issues is energy preference settings being stored by other programs for your old storage device, perhaps now accessing your new drive imposing obsolete, and conflicting settings. When I first experienced some of this behavior at discussion, I had replaced my 2 TB WD MyBook Studio for Mac with a 4TB Seagate Backup Plus for Mac drive. The WD has power management options and when set were also being stored by Time Machine. The answer is to delete the offending file. I deleted the preference file for Time Machine (not to worry, the Mac makes a new one ;-)), by doing the following:
1) Turn off Time Machine via Time Machine Preferences window.
2) Open the 'Finder' window.
3) Eject External Hard Drive via 'Finder' window.
4) Click on Macintosh HD.
5) Click on Library.
6) Click on Preferences.
7) Locate the file named 'com.apple.TimeMachine.plist' and DELETE it (Move to Trash).
8) Restart your computer
Now for another one: Once your drive is installed successfully and is functioning properly, if you've had a problem with Time Machine not being able to access your backup data, when you know the data is there and you can see your backup folders plain as day, an item that may warrant your attention here is a permission reset if you've moved data from the old storage device to the new one:
1) Reboot and hold Command + R
2) Terminal and type 'resetpassword' (no spaces)
3) Select main drive at top of dialogue box that appears, then select 'reset permissions/ACL at the bottom of the box.
4) Reboot computer.
5) Open 'Disk Utility' in Apps and reset main hard drive permissions.
6) Reboot computer.
This process resets the user permissions folder. One way to avoid going through all of this is to use your 'Migration Tool' found in your Apps folder INSTEAD of the old copy and past from the old to the new.
This one probably goes without saying; however, I've read many, many forum complaints that the backup software that came with their drive either won't install or doesn't function properly on their mac. USE TIME MACHINE. Most storage device Manufacturers even specify to use Time Machine instead of their own software. The major players in the field don't even make BackUp software for Mac. They'll format the drive for Mac (in most cases :-/ ) but that's it. There is a reason for this; no other backup software comes close to keeping your files as safe and secure as they will be with APPLE Time Machine.
Hope this helps some people.
Happy computing!"
Just this week my computer did another software update, and again I was having issues so I had to dig up this post again. If the steps above solve your issue, SAVE THEM TO A TEXT DOCUMENT FOR LATER REFERENCE. I can tell you from experience that you'll probably need to reference it again - and considering all the posts and complaints about external hard drives it will be difficult to find it again [it was several months ago that I first needed it, so it was difficult for me to remember the exact search criteria that led to my issue being resolved].
TL; DR: My problem narrowed down to a "com.apple.TimeMachine.plist" file. For whatever reason, deleting this file and rebooting my computer fixed the issue. In the future, any time my system goes through an update I'm deleting that file and rebooting [the system will recreate this file automatically].
I hope that this helps you guys. As a film editor I know how absolutely infuriating it can be to not have access to your hard drives or worse - losing data.
Good luck and Godspeed. :]
