Anyone else having problems with external disks unmounting randomly/suddenly on Mavericks?

DISCONNECTING DRIVES SURING BACK-UP AND/OR FORMATTING IS A MAVERICKS ISSUE.

i have just reverted to a different hard drive with my old SNOW LEOPARD system on and formatted the mavericks drive - IT DID NOT DISCONNECT over 12 hours of whole process.

also - i described trying to remove partition on a hard drive and MAVERICKS hung during 'preparing to remove partition' meaning i had to close down using power button. NO HANGING ON SNOW LEOPARD - SO THIS TOO IS A MAVERICKS ISSUE.

I have had the problem for months with Lion on an old 26" iMac. I have three corrupted disks that cannot be repaired so far including the internal drive. Other people using Snow Leopard have reported the same problem. Until I bought a new MacBook Pro just a few weeks ago I have never used Mavericks but I am now having the same problem using Maveriscks. It may be more common with mavericks but it is certainly not only a Mavericks issue.

Just discovered our problem was anti-virus that most likely broke during the in-place upgrade to Mavericks. ESET NOD32 was crashing repeatedly and somehow causing the USB sticks to be ejected.

I strongly advise people to check their logs in the Console.app to see whether they also see some clues as to what may be causing their USB drives to spontaneously un-mount.

Hope that helps.

Steven Boothe

Computer Technician
Cuesta College

The disk ejection problem has been widely reported here and elsewhere. It's not an SATA card problem In most cases. I never see improper disk ejection in Snow Leopard, but always see it on the same computer when running Mountain Lion. The 10.8.5 supplemental update did not help. I also saw this behavior consistently in Mavericks, but that may have been fixed in 10.9.4.

Was having the same issue on MBP with USB 2.0 under Mavericks 10.9.4. Problem was only occurring with a Fantom Greendrive (long USB 2.0 cable), but did not seem to be happening with a Seagate drive (short USB 3.0 cable). Both are plugged into a USB 2.0 port.

I tried various recommendations here for sleep, reformat under Mavericks, clean Mavericks install, but my disconnects were occurring with the machine on, awake, plug in the drive, start a large file transfer across the network. I either got a slow copy, with sporadic pauses, and or painfully long pauses with sporadic slow copying, then a disconnected drive.

I eventually found a different USB 2.0 cable that had filters installed at both ends of the cable. The Drive has not disconnected since the cable change out and transfers are now back to where they should be.

Since this problem didn't happen under windows, and on a different PC (never tried this drive on the MBP prior to Mavericks), I can only guess at the issue being isolated to Mavericks. Possibly the USB code was modified to be more sensitive to noise on the line in order to disconnect the drive and prevent possible bad data from being written or read. Doesn't make too much sense as I would think the USB transfer protocol should already handle this. Then again Apple has been known to stray from standards before (i.e. Apple Thunderbolt implementation), so who knows if this is the case. Only Apple knows what they did and why, and they usually don't tell.

I'd suggest trying a filtered USB cable if you are still having problems.

Sad to say that is not exclusive for Mavericks, i never update to it, and still have 10.8.5 imac 21" Mid 2011, it happens with my uSB 2GB WD elements.. however, i also have a Firewire LAcie 1Tb that never had any issues, keep in mind that probably is related to USB department only... i will need to have another usb HD to test it,

your WD issue could cloud this one as Western Digital arguably make the worst most unreliable drives available. it's safe to say you can't assess this issue or any other drive issues using any WD drives. they're the first to fail.

all the consistent evidence so far still points to a Mavericks system problem.

It seems to me that we may be onto something here. A number of people are having the exact same problem with snow leopard and Lion so obviously Mavericks is not the problem although it may happen more with Mavericks.

I just got a new internal drive from iFixit so I can replace the dud one. The original drive is a WD drive but unfortunately you have to replace with the same drive type so the new one is also WD. One of my backup drives that unmounts is a WD drive and I just took apart one of the two Imation external drives only to find they also have WD drives inside.

It looks possible that the problem may be caused by WD drives. I thought most of my external drives were Imation but it turns out the actual drives inside are WD.

i refer to my previous post regarding WD drive.

who told you to replace the drive with the same make? as long as the specs of a drive are suitable to be used with your operating system and can be formatted in the correct way, you can use any make of drive that is compatible. this issue has nothing to do with WD. plenty of people have commented using other makes of drives. this issue did not arise for me until i downloaded Mavericks - none of the three drives that got corrupted were WD but very reliable Toshiba / Samsung / Seagate drives.

i had no issues with any of these drives for years using snow leopard and have had ZERO issues with the same reformatted drives after returning to snow leopard.

iFixit said the drive must be the same type because if you use a different one the temperature sensors are different and could result in the fans going full on, non stop. This is an internal drive in an iMac, not an external drive where, as you say, it would not matter.

Your personal experience with the problem is with Mavericks, mine is with snow leopard and lion, as some others are so it cannot be only a Mavericks problem. You won't find a solution by ignoring evidence. We will only find a solution by looking at ALL the evidence and not only what applies to your personal experience.

Are you sure those drives are not WD? I thought my imation drives where imation until I opened them up and found they were WD.

i am absolutely positive none of them are WD. mine was a macbook pro so obviously different drives. to be honest i am SHOCKED to hear you have a WD in anything to do with an Apple product. i'd be suspicious about that being the generic supplied drive. and i AM talking about internal drives - not external ones. only one of my drives was an external backup drive. both others were configured especially for MAc use and i5 processor power management.

if your WD drive was supplied at time of purchase form Apple - i'd be asking for a replacement for free as WD are recorded as one of the worst hard drive manufacturers going. i wouldn't touch them with a barge pole. hence you can't properly isolate your issues when using WDs they're just too unreliable for testing.

Actually some months ago I did receive an email from Apple saying I was entitled to a new disk drive and I should contact the nearest service centre. I contacted iFix out nearest service centre in Davao Philippines. They said they would schedule the replacement and call me. After a long wait I contacted them again and they repeated that they will contact me when it is scheduled. I waited for a few more weeks and contacted them again and got the same answer again. Then once more I contacted them and they said "Its too late now. It is past the deadline. You should have brought it in."

Then they said they could replace the 2TB drive with a 200GB drive for about 3 times the cost of a new 2TB drive.

This is why I am replacing the drive myself.

The simple way to see if a drive is a WD drive is to run Disk Utility The drive number will start with WD.

Seems like a variety of problems dog-piling onto this post. I was having two related problems I reported here a while ago: 1) My drives would spontaneously eject and 2) they would not re-mount after the computer woke from sleep, but Finder thinks they're mounted and chaos ensues.

Somewhere along the line, the spontaneous ejection problem went away for me--not sure what I did to fix that but it might've happened as a result of repairing the drive in the disk utility. The other (and more significant) problem still remained (drives remaining unmounted after computer wakes from sleep, but Finder thinks they're still mounted.)

My specific setup was a 2T Western Digital black and a 4T Wester Digital black drive in an Icy Dock dual disk enclosure set in JBOD mode (meaning it's just two separate drives.) The interconnect is USB3. I was using the 4T drive for time machine and the 2T drive for storage.

I did several experiments with different drives in different enclosures (including a couple of 1T drives I have) and finally narrowed my problem down to a specific 2T Western Digital Black drive. If I removed that drive from my system, my other drives would be happy and reliable regardless of other system variables. Conversely this 2T WD Black drive would get stuck after wake from sleep no matter which external enclosure it was in. I even caught it misbehaving in a Firewire enclosure once.

I bought a 4T Seagate the replace the 2T Western Digital and the problem is, so far, gone. So now I have two 4T drives--one WD and one Seagate. As a bonus, I noticed both drives are a lot faster with the 2T drive gone. I didn't get Seagate for reliably reasons (Seagate is the least reliable brand according to Backblaze)--I only got it because it's different (and it happens to be very inexpensive as well.) Besides, even the least reliable drive is still very reliable.

Another thing I discovered was my 4T Western Digital drive had gotten quite corrupt over the last several months--probably as a result of all these nasty disconnect problems. It was so bad that the disk utility couldn't repair it. Reformatting it cleared the problem and had the added bonus of making the speed far greater (it was previously running about 60MB/s and now it's up at 150MS/s). So there's might've been something going on there as well.

Again, I think this problem we're all posting about isn't one problem. So what I didn't may not help others.

So in Summary: 1) try removing and rearranging individual drives from your setup and see if your unmount/wake-from-sleep issues are related to just one of them; 2) repair the drive in disk utility (and if that fails--reformat it.)

Another tip is sometimes a drive needs to be formatted in the enclosure it's in to work reliably. I had this problem with my 1T WD black drive once.

Another thing some brave folks might consider trying is the Yosemite public beta. Who knows, maybe that'll clear the problem. If the problem still exists there, then at least you'll probably get more attention when you report the bug.

Bart

It looks like we are making real progress. My iMac is by far the worst with drives unmounting and that has a WD internal drive.

I have just replaced the drive. I was told by iFixit that is must be the same type or the temperature sensor may be incompatible so I bought another WD drive. I just replaced the drive in the iMac and found the temperature sensor is just stuck on the outside of the drive so I could have installed a better drive.

If the problem still exists I will replace the drive again.