Re-formatting iMac's Corrupted Hard drive..Suggestions please

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Re-formatting iMac's Corrupted Hard drive..Suggestions please

Because of a failed Optimisation I feel I now have to completely wipe, re-format and re-load OSX onto my iMac's internal HD, but never having done this before I want to make sure I don't end up in more of a mess then I am in right now! So I'd appreciate any advice as to the best way to go about this.

My iMac is a late 2009 27" and at present has OSX 10.8.5 loaded, ( loaded but with many miss-functions ). Prior to the problem the iMac was running OSX Lion, what version though I can't remember.I installed 10.8.5 the other day to see if that would fix things, but it hasn't. It was not a "clean install", just regular one from downloaded OSX 10.8.5.

I have run Disk Utility and TechTool Pro' 7 to try to make repairs to address the problems so far to no avail. Main problems are that my most used applications, FCP-7 Studio, Aperture and Photoshop CS5 amongst others, open but then immediately crash. I've reloaded the troubled applications, de-installed them properly with de-installation app's then clean re-installed them, but that's made no difference. They will not mount.

I reckon there must be a fault or corruption on the HD, probably caused during the Optimisation as everything was functioning well before I did that.

So, the only OSX install disks I have are the original disks that came with the iMac, OSX 10.6.2 and a Snow Leopard Upgrade DVD OSX 10.6. I do have the downloaded copy of OSX Mountain Lion that I pulled from the App Store the other day and that copy is now on an external USB / Firewire 800 HD.

As I said I would like to be able to clean off the iMac's internal 2tb drive completely and install a fresh newer OSX. If I first have to load OSX.6.2 then upgrade via the App Store that's fine, but I'd rather just go straight to Mountain Lion if possible. Whatever works best. Getting rid of any corruption on the iMac's HD is the prime motivation.

All my applications and files are backed up to a 2tb LaCie external drive.The iMac has approximately 900 gb's of content onboard and the rest is free / unused space.

I would very much appreciate all the help and suggestions as to how I can safely go about the wipe and re-installation of a fresh OS. I fear doing this without good advice I could very well "brick" the iMac!

Thanks!

PM

Posted on Sep 6, 2014 2:59 AM

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Answer 1

Top-ranking reply

Eric Root

Level 10

684,615 points

Sep 6, 2014 8:52 AM in response to Peter Mullett

Boot to the Recovery Volume (command - R on a restart or hold down the option key during a restart and select Recovery Volume). Run Disk Utility Verify/Repair and Repair Permissions until you get no errors. In Disk Utility, select the erase tab. Select the drive, then click Options and select GUID. Format is Mac OS Extended (Journaled). Then re-install the OS.

OS X Recovery

OS X Recovery (2)

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Answer 2

Sep 25, 2014 4:40 AM in response to Eric Root

I managed to get my iMac up and working again, this time running OSX 10.8.5…..But now I am finding that my most important application FCP7 Studio has some "quirks" running under the upgraded OS so I would like to revert to OSX Lion. How can I do this, and would it be possible to install Lion on a separate partition, ( presumably with FCP7 on that partition too ), and have 10.8.5 or higher on another partition?

One other thing. I have downloaded OSX Lion from my "previous purchases" on my Apple App Store account, but as soon as it downloaded it reported that it couldn't run on the iMac presumably because I've 10.8.5 as the machine's OS. Then it quit and VANISHED! Can't find it in Downloads or Trash….and now when I tried to download it again the App Store reports it as "Downloaded" and is greyed out….How can a get a copy to retry?

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Answer 3

May 15, 2015 8:22 AM in response to Betacruxis

Betacruxis,

Did you end up finding a way to fix your problem? I have what appears to be the same problem. My Disk Utility screen looks like the one you posted 6 months ago.

I was secure-erasing the HD in order to sell the Mac. There was an error during the secure erase at some point. Now I'm stuck with the screen you showed. I've ran Repair Disk many times with no errors showing up.

Thanks!

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Answer 4

Eric Root

Level 10

684,615 points

Sep 26, 2014 7:52 AM in response to Peter Mullett

Boot into the Recovery Volume by holding down command - R during a restart or by holding down the option/alt key during a restart and selecting the Recovery Volume. I've partitioned my drive several times and have had no problems. I would make the new partition about 40-50 GB to ensure you had enough room in case of future growth.

Steps to partition. Add step 5 ½ - click the options button and select GUID. When you format the new partition, it must be selected.

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Answer 5

Nov 16, 2014 5:32 AM in response to Eric Root

Hi,

I had to reformat my hard drive due a corruption too, as instructed by the very Disk Utility.

So, I did all the steps above and when "erasing" the disk I got a message stating that the mounting point of the hard drive was incorrect due to a bad format.

In conclusion, I can see the HD in the disk utility, but the logic disk is not available, either for the utility or to reinstall the OS, as you can see in this pic:

Also, as you ca see in the pic, there is no access to the functions the utility has to manage the disk, do I cannot reformat, partition or anything.

Any help will be appreciated.

Thanks.

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Answer 6

Eric Root

Level 10

684,615 points

Sep 25, 2014 9:29 AM in response to Peter Mullett

I would like to revert to OSX Lion. How can I do this,

Revert to a Previous OS X

would it be possible to install Lion on a separate partition

Yes. Boot into the Recovery Volume again and use Disk Utility to partition the disk.

Is the Installer in your Applications folder? That is where it downloads to. When you start it, you can point it at the new partition and install it there.

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Answer 7

Sep 25, 2014 10:01 AM in response to Eric Root

Hello Eric, thanks for the reply, I really appreciate it…..

Yes the installer is in my Applications Folder on the iMac, ( now running Mountain Lion ).

How safely do I boot into Recovery Volume? I have to confess being nervous about messing with the HD so soon after floundering my way through recovering it all, but not being able to run FCP7 well under Mountain Lion is a pain I need to try to address.

The 2TB hard drive on the iMac has only about 600 mb used, so there's plenty of room for a partition I guess, and the Lion partition would only be used for the FCP7 program. What size would you think would be safe to make. All FCP files are always stored / saved to an external Raid drive.

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Answer 8

Eric Root

Level 10

684,615 points

Nov 16, 2014 7:37 AM in response to Betacruxis

You might want to consider starting a new discussion. Since this one is marked solved, less people are likely to look at it. You can link to this one.

Do a backup. Your hard drive may be failing. Have you tried booting into the Recovery Volume (command - R on a restart)?

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Answer 9

Nov 16, 2014 2:43 PM in response to Eric Root

Yes. I did all of that.

The image shows the Disk Utility, but already in Recovery mode.

As you see, there is no logical unit to use for installation.

What I need is to figure out how to recover/create/unlock that partition.

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Answer 10

Nov 17, 2014 12:26 PM in response to Eric Root

No, encryption is off.

I already tried all conventional methods, even those described by Apple, but all of them assume the logic volume is available, which is my very problem.

I'm going to Genius Bar.

Thanks anyway.

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Answer 11

Paco2000

Level 1

8 points

Jun 14, 2015 1:28 PM in response to TheBradleyRoberts

Betacruxis & TheBradleyRoberts,

I do have EXACTLY the same problem, and I tried everything several times, and NOTHING has been worked at all. I was secure-erasing th HD in order to re-instal OS and was an error . I am stuck with the screen you showed.

I don't know what I am going to do, I have been trying every single tip I found online and nothing worked after almost 5 days. I will have to take my iMac to Apple or call "MacDoctors" here in Los Angeles.

Hope someone can help me!

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Answer 12

Jun 15, 2015 9:34 AM in response to Paco2000

Paco2000,

I had to take my computer into the Genius Bar. The genius there was able to fix the problem for me without much effort. He said the issue stems from the Fusion Drive itself, when a problem happens during formatting, it makes it hard to fix it. What I saw him do was boot to an external copy of OS X (he actually used an older version that Yosemite.) From there, he had to use Terminal to do the format. Then he booted to the newest version of an external copy of OS X and installed a fresh copy. I asked if that was something I could have done at home, and he said yes, but that it would have been difficult and taken a lot longer. In the end, if you can take it into a Genius Bar, do so.

Good luck,

Brad

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Answer 13

Eric Root

Level 10

684,615 points

Nov 17, 2014 10:32 AM in response to Betacruxis

Do you have FileVault on? If so, Disk Utility/File/Turn off Encryption.

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