Q: external drive ejects at sleep

Same problem with my 3tb western digital external drive and 4tb seagate external drive. It changed the names of my external drives to numbers and symbols and the date the drives are created is Wednesday 31 December 1969 and last modified Monday December 31 , 1979. I've done repairs and still nothing . Since update 10.8.5. I've also had no sound from HdMi to TV from 2012 late Mac mini after waking from sleep. So the issue appears to be something with the sleep.

Best solution so far:

I simply booted up in Recovery HD (hold down command and R at startup) and selected "Restore from Time Machine Backup." I then selected my last 10.8.4 backup (which thankfully was only five days prior), and within 40 minutes was up and running in no time.

The problem is gone and it's running fine again.

Just make sure to use a flash drive to backup any files created after you updated to 10.8.5 because they will be lost. Once you revert back to 10.8.4, just copy them back to your computer.

Very easy and worthwhile solution.

Just unfortunate...

A update and... surprise! you have to go back because it doesn't works fine ...

This is the same as "the windows way": XP vs Vista...

Professionals as we look from the sidewalk, surprised, saddened and fearful...

I still do not understand how you can get an update that doesn't work fine and causes failures in the daily work of professionals.

This is serious, Apple...

I just hope that Mavericks is the same, a "good" job...    

Thanks Machwa and others for your comments and solutions

Works with my MacMini and a WD Thunderbolt Drive.

THX!

(You should additional autopoweroff to 0)

Just FYI,

Apple Support contacted me the other day and asked me to run some diagnostic tools to gather some logs. So, they are looking at the problem.

The Apple respresentative couldn't give me any timeframe for when a fix might come along though, but at least they're looking into it.

Same problem for me:

WD MyBook Thunderbolt Duo RAID, 4GB on an iMAC late 2012 - problem exists since upgrading to OSX 10.8.5

works fine, but the spleep is not so deep as before i think...

sudo pmset -a standby 0

works for me - WD myBook Thunderbolt RAID

These Apple updates fixing some things a breaking a slew of others is just getting ridiculous.  I have had various issues.  This disc unmounting issue is extremely annoying.  What happened to "It Just Works".  I guess Apple does not really pay attention to details anymore.  Very frustrating.

Same like the rest...  Latest iMac i7 27"

External 256 Thunderbolt SSD by OYEN.  Worked PERFECTLY on .4 now ejecting after every sleep with .5

What a time waster.

Yet another, and yes I have sent a submission (complaint) to Apple. Let's hope the fix it soon.

If you cannot restore back to 10.8.4 you can temporarily fix the issue by setting your monitor to never sleep which ironically keeps your disks from going to sleep too.  I submitted feedback to Apple and received a couple of phone calls and was told Apple is investigating this issue, but there is no ETA on when the fix will come.

sudo pmset -a standby 0

This is a good suggestion.  I fired up a terminal session and checked the settings (pmset -g).  In my case, the standby parameter is set to 1 and hibernatemode is set to 0 (iMac).  As Mark Levitt1 pointed out, these two settings appear to be in conflict and therefore possibly are an invalid combination according to the man page for pmset.

Any of you guys that are developers and have submitted a bug report, are there any updates?  This issue is very annoying.

It has become so frustrating that everyone has become a beta tester.  This is now a recurring theme.  I just saw that they puled Apple TV firmware 6.0 from their updates as it was bricking the Applle TV's.  I feel that the bigger the company gets, the more arrogant they get and they could not care less about the customers that keep buying their products year after year.

Unfortunatelly, my MacBook Pro does not support the "standby" parameter, it is not visible with "pmset -g". I have a second HDD build in instead of the optical drive. The MacBook Pro is running 10.8.5 Server and all nonSystem HDDs are spinning down short time after the display goes to sleep. This is really annoying! The Machine also runs as TimeMachine Server, backing up three Macs on the Network to an external drive connected via eSATA over an expresscard 34. Drives connected via USB and FireWire and the second internal drive spin down either. As the display of the Machine is always in sleep mode (the server does not need the display at all, because I manage it remotely), the drives spin up and down all the time. Especially the TimeMachine Drive spins up and down all the time becaues of the one hour intervall for TimeMachine on three Macs.

The man page of pmset says:

"standby causes kernel power management to automatically hibernate a machine after it

     has slept for a specified time period. This saves power while asleep. This setting

     defaults to ON for supported hardware. The setting standby will be visible in pmset

     -g if the feature is supported on this machine."

So this solution seems not to work on mobile Macs which do not have the "standby" feature.