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Diogones

macrumors regular
Original poster
Dec 23, 2009
189
4
Hey all,

I have an early 2008 24" 2.8GHz iMac with a 120GB Intel 320 SSD and 6GB RAM that I installed myself. I performed a clean install of Yosemite 10.10.0, and with the 10.10.1 update, there were no issues, and the machine ran fine. However, when I attempted to update my Mac to 10.10.2, I ran into a serious problem.

Like many Yosemite users, it was very difficult to download the update from the Mac App Store update tab when it was first released. The download was occurring at a very slow rate taking well over two hours . I wasn't using my iMac for anything else during this time.

At some point during this process a family member accidentally unplugged the router. I went back to the Mac to check on it, and although the update was only halfway downloaded according to the App Store, the computer automatically restarted to apply the update before I could stop it.

I saw the update progress bar and the update seemed to install without any problems. However, when the Mac went to reboot, I was greeted with the prohibitory symbol. I tried restarting several times without success. I also tried to boot into Safe Mode and even single user mode, and neither worked. I also reset the SMC and zapped the PRAM, which didn't help. I also booted into the recovery partition on the drive and ran Disk Utility's repair disk on both the partition as well as the disk itself, and ran a permissions repair. It also didn't work. :eek:

I even hooked up my iMac to a friend's MBP via Firewire Target Disk Mode, and installed the 10.10.2 standalone update to the iMac, but it also didn't work. I was going to attempt the 10.10.2 combo update, but I read that it wasn't working for 10.10.1 systems, and only worked for 10.10.0 installs. I have a copy of the Disk Warrior 4.4 CD, and I booted up from that on the iMac and rebuilt the disk directory, but no luck. :(

Fortunately, I do have a Time Machine backup on an external HDD. I also don't exclude anything from the TM backups, which includes the System folder from OS X, so I attempted a restore from from my backup using the recovery partition. I have backups from well before the install began. I first tried earlier in the day before the install began, and when that didn't fix anything I tried a restore from a backup from a few days ago, but that didn't even work either!

Finally, I was forced to do an in-place reinstall of Yosemite from the recovery partition. The reinstall worked, and I was able to boot successfully into the desktop. Unfortunately, I have some missing files, specifically two months worth of Quicken data entry and part of my documents folder. I do know that I backed everything up via TM, so I'm not sure why those items are missing. Also, my Chameleon SSD Optimizer app won't open, and appears to be corrupted.

I'm trying to understand what exactly happened, and if there was another method I could have taken to get the Mac working again, other than the laundry list of things I tried. Since I had the iMac fully backed up (including system files) with TM before I tried to download and install the botched update, should I have tried to format the OS X partition with my recovery partition, and then run the TM restore so it could have replaced the corrupted system files with the working backup copy, rather than perform an in-place reinstall of Yosemite? Could I still do that now to get my files back?

Another thing I don't understand is why the Mac ran the update after it lost Internet connection in the middle of the update, which wasn't even finished downloading. Shouldn't the system have checked the update to ensure the entire bundle was downloaded before executing the install process?
 
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Thanks for the prompt replies! Good question, too.

No, it's not the Cindori Trim Enabler, it is the Chameleon SSD Optimizer, which I mentioned in my post. Might that have something to do with it?

EDIT:

Ooh it looks like it could be the culprit! Here's a quote directly from the Chameleon SSD Optimizer website under the FAQ page:

HOW TO: YOSEMITE and kext sign control

If you encounter a block sign on boot after appling[sic] patch for trim try this way to force disable kext sign:
boot from recovery with cmd + r at startup, then manually in terminal:
"touch /Volumes/<YOUR DISK>/System/Library/Extensions"
than

"kextcache -u /Volumes/<YOUR DISK>"

It appears that the 10.10.2 update may have re-enabled the kext signing feature, so that when the Mac rebooted, the TRIM driver was detected and blocked and thus OS X refused to boot normally. I'm surprised I didn't see this message when I tried verbose mode, but I may simply have missed it among all the other startup messages.

According to simonsi's helpful link, the developers for the TRIM Enabler from Cindori discuss this issue as well when enabling their program in Yosemite.

This would also explain why - in System Information under the SATA category - my SSD is listed as having no TRIM support. It could also possibly explain why the Chameleon SSD Optimizer app itself was corrupted; the 10.10.2 update and the subsequent in-place install restored kext signing and removed the TRIM driver Chameleon was enabling, thus corrupting the app or removing crucial files it needs to run.

I may also have been mistaken about the update's download progress as well. It may have appeared to have been incomplete when the Mac restarted, but that simply could have been my error, or the progress indicator in the App Store had properly updated to reflect the current status of the download.
 
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Thanks for the prompt replies! Good question, too.

No, it's not the Cindori Trim Enabler, it is the Chameleon SSD Optimizer, which I mentioned in my post. Might that have something to do with it?

EDIT:

Ooh it looks like it could be the culprit! Here's a quote directly from the Chameleon SSD Optimizer website under the FAQ page:



It appears that the 10.10.2 update may have re-enabled the kext signing feature, so that when the Mac rebooted, the TRIM driver was detected and blocked and thus OS X refused to boot normally. I'm surprised I didn't see this message when I tried verbose mode, but I may simply have missed it among all the other startup messages.

According to simonsi's helpful link, the developers for the TRIM Enabler from Cindori discuss this issue as well when enabling their program in Yosemite.

I may also have been mistaken about the update's download progress as well. It may have appeared to have been incomplete when the Mac restarted, but that simply could have been my error, or the progress indicator in the App Store had properly updated to reflect the current status of the download.

Yes its the same issue as Cindori have, the app kext isn't signed or kext signing is disabled to let it run and hence OSX won't let it boot.
 
I'm glad that I was able to understand what was going on here thanks to simonsi!

So I guess my only remaining question is, if I wipe the partition and restore the system from my TM backup, would that recover my missing document files? I don't have to worry about running into the prohibitory sign again due to TRIM and Chameleon being disabled.
 
I'm glad that I was able to understand what was going on here thanks to simonsi!

So I guess my only remaining question is, if I wipe the partition and restore the system from my TM backup, would that recover my missing document files? I don't have to worry about running into the prohibitory sign again due to TRIM and Chameleon being disabled.

If you know where the files were, simply choose "Enter Time Machine" from the TM menu and browse to where the files were when you last saw them and restore just those files from there. No need to wipe a partition just for a few TM files.
 
I'm glad that I was able to understand what was going on here thanks to simonsi!

So I guess my only remaining question is, if I wipe the partition and restore the system from my TM backup, would that recover my missing document files? I don't have to worry about running into the prohibitory sign again due to TRIM and Chameleon being disabled.

That should be o.k. but I'm a little bit confused about the current status?
Perhaps as simonsi mentions, you only need to recover a few files.

If you strike the problem again you might need to invoke the "Restore to Original" procedure and not just the part you quoted earlier.
http://chameleon.alessandroboschini.com/faq.php

The "Recovering from stop sign on boot screen" procedure here is also good to have available in case you need it:
http://www.cindori.org/trim-enabler-and-yosemite/
 
If you know where the files were, simply choose "Enter Time Machine" from the TM menu and browse to where the files were when you last saw them and restore just those files from there. No need to wipe a partition just for a few TM files.

Thanks simonsi, I think that's exactly what I'll do! ;)

That should be o.k. but I'm a little bit confused about the current status?
Perhaps as simonsi mentions, you only need to recover a few files.

If you strike the problem again you might need to invoke the "Restore to Original" procedure and not just the part you quoted earlier.
http://chameleon.alessandroboschini.com/faq.php

The "Recovering from stop sign on boot screen" procedure here is also good to have available in case you need it:
http://www.cindori.org/trim-enabler-and-yosemite/

Yes, thank you for those guides alex! I'll bookmark those and possibly even just print them out in case I do run into this issue again, whether it is a future update or something else which might re-enable kext signing.

The current status is that everything seems to be working ok after the in-place reinstall I did. I had to reactivate some software and set some apps up for the first time, as the in-place install replaced or removed some of the Application Support files in the system Library, among other program files.

I will have to re-enable TRIM and Chameleon SSD Optimizer again, as the current install of that program was in fact damaged, and needs to be replaced with a new copy.

I am missing some files in my documents folder and two months of Quicken data entry, but TM should have that saved from before this fiasco happened, so I can simply restore them from the TM UI, as simonsi suggested. Hope this clears things up alex. :cool:
 
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I will have to re-enable TRIM and Chameleon SSD Optimizer again

Just as an aside, I opted NOT to run Trim Enabler on my Crucial 120GB SSD after installing Yosemite....no measurable speed slowdown or lifetime shortening has taken place according to DriveDX...
 
simonsi wrote above:
[[ Just as an aside, I opted NOT to run Trim Enabler on my Crucial 120GB SSD after installing Yosemite....no measurable speed slowdown or lifetime shortening has taken place according to DriveDX... ]]

I concur.

I've been booting and running a late-2012 Mini since January 2013, using (first) an Intel 530 series SSD and (later) a Crucial m500 SSD, mounted in a plugable.com "lay-flat" USB3/SATA docking station.

The Crucial drive has been in place for 11 months now. It runs as well as it did when first initialized, and TRIM has never been enabled. The Mini is heavily used, sometimes on from 9am until past midnight.

So long as one doesn't "fill up" an SSD beyond 75-80% of capacity, I reckon that TRIM is an "overrated issue" insofar as modern SSD's are concenrned.

My opinion only.
I could very well be mistaken.

But that's my experience...
 
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