iMac HDD questions

Yes, you can boot with a thunderbolt/USB 2/FireWire drive. Just plug the drive in, if it is already a boot drive you should be all set. (Just use the option key at boot to see all the available bootable drives.)

If you need to permently boot from an external drive, I would use a thunderbolt drive, as it will be much faster than USB 2/FireWire. Usb2 would be fine for testing, just slow. I use a ssd in a delock thunderbolt adapter for my external boot drive, it is much faster than the stock hdd.

FYI: if you do want to open the iMac up and replace the internal hdd instead, you will need either a software solution or hardware fan control sensor (owc sells one) to use anything other than the original iMac hdd.

 

You can boot and run the Mac from an external drive.
It will run as well as booting from the internal drive, and can give you a few more years of use out of the iMac.

I've done this for many years.

Questions:
What indication do you have that the internal drive is broken?
Do you think it's a hardware failure? (platters not spinning, etc.)
Or could it be a -software- failure? (corrupted OS)

You wrote that you have a bootable USB drive with Mavericks on it.
Are you currently booting up and running this way?

If so, when you get to the finder, do you see the internal HDD on the desktop?
If not, can you see it in Disk Utilty?

Final thought:
The 2011 iMac has thunderbolt, is this correct?
If so, you could buy an external thunderbolt drive with an SSD in it, and you will have a much faster booting/running iMac than you did with just the internal HDD...

 

Just to check, are you sure the external USB keyboard you are going to use supports the startup boot commands? I remember hearing that some third part keyboards do not. I have just used the stock Apple Bluetooth keyboard, I have not tried it with third party keyboards.

 

For a third party USB keyboard, you may just need to swap the keys you hold instead, as best as I can tell:
https://discussions.apple.com/thread/4857405?tstart=0

I would think there is a way to pair an official Bluetooth Apple keyboard for the first boot, but to be fair I don't know it off the top of my head. Best of luck.

 

The more I think about it, the better off you will be with USB vs Bluetooth keyboard for troubleshooting. Even when already paired, there is an art to the timing needed to invoke the keyboard commands (when the green Bluetooth light comes on during the boot sound, but not more than a second later.)

If you are going to find a generic USB keyboard, I would suggest getting a cheap version (without media keys and other functions that require a driver.). Of course, buying one from a place that allows returns is a given as well. After everything is sorted, you will probably want a Apple specific keyboard as well, the for sale fourm section here usually had a few of them listed every week or so by someone. Owc usually has used Apple keyboards, but I am having issues finding them today on their redesigned web site.

--- Post Merged, Feb 11, 2016 ---

Here is a link to all the boot commands as well once you get the keyboard situation sorted out. It may be helpful, if the 2011 iMac has up to date firmware, Internet recover should be available...

https://support.apple.com/en-gb/HT201255

 

I ran into similar problems with a friends unit. We ran a test on the drive with Scannerz which showed the drive still working but obviously it had a head crash, so he wanted it replaced. Some of the people on this site are more adventurous than I am, but this wasn't my system and I could just visualize me busting something on someone else's machine if I opened it up. What we did was get a thunderbolt enclosure and an SSD, installed the OS on that and he now uses it as the system drive. He did have to add some type script to his start up to unmount the internal drive when he starts up, but I don't know much about that.

Regarding keyboards, I have an Apple wireless. Great keyboard...unless you need to try to boot using one or more keys pressed down (like going into safe mode or pressing the alt key during boot). When I do this with the wireless keyboard, sometimes it works and sometimes it doesn't. It's almost like there's a timing problem with the system knowing the keyboard is connected. To overcome this I bought a second Apple USB keyboard off of eBay for about 5 bucks. I think it was from one of those old iMacs because it's bottom is reddish. I think they called it strawberry or raspberry or something like that. You could probably do it with some other cheap keyboard too, but you'd have to figure out how all the keys map.

 

Run Disk Utility while booted from the Yosemite USB. Pay particular attention to the S.M.A.R.T. status at the bottom right of the Disk Utility window. If it shows anything other than "Verified" your drive is physically failing. If it shows "Verified", you problem may only be disk directory corruption.

If the disk shows verified, try running Repair Disk from Disk Utility.

If it does not show verified, you need a new drive.

 

Yes. That sound is the HDD failing. Put a new one in and problem solved.

If you are adventurous - like me - and thrifty - like me - you can buy any SATA HDD you like to install, you don't have to put an official Apple one with a temperature sensor. There is a software app. called "Macs Fan Control" that you can download for free, that regulates the iMac fans for you so your computer will stay silent. An added bonus is that if - like me - you do gaming in an emulator like Fusion or Parallels, you can set max temp thresholds for the GPU diode and heatsink, which will stop it overheating and limiting your gaming experience.

(FYI: I too have a mid-2011 27" iMac)

 

Have another look in Disk Utility. Look at the bottom right corner of the Disk Utility Window when clicked one each of the two Mac HD's. In one of them, it should show the S.M.A.R.T. status. If that is anything other than "verified", your hard disk is failing and needs replacing.

If it shows as "verified", more likely you have disk corruption that needs to be fixed, but you may not have to replace the drive.

You have two choices in that case:

1. Back up the drive to an external hard drive. I would recommend Carbon Copy Cloner (http://www.bombich.com) to do this. Then erase and reformat the drive and clone back from the external.

2. Buy a heavy duty disk repair utility like Disk Warrior http://www.alsoft.com and see if it will repair the drive.

 

Just to point out, these are my opinions, I am sure others will chime in with their thoughts of internal/external drive, and DIY replacement vs taking it to a shop.

You can use a Thunderbolt/USB 2/FireWire drive to boot from, but the only external drive option that will come close to acceptable speed for daily use in my opinion is thunderbolt. I am using a Crucial 1tb SSD in a Delock Thunderbolt enclosure, it works great for me. (My internal HDD is working fine, but using an external Thunderbolt SSD gave the iMac an incredible increase in speed.)

Another option instead of running an external thunderbolt drive would be to simply replace the internal drive. As mentioned above, replacing the drive will cause a run-away fan situation. There are two options to correct this, either the software program described above, or OWC sells a hardware temperature sensor that allows any drive to work in place of the failed one.

My only concern with using an external drive WITHOUT removing the failed one would be if an app tried to read or access the failed drive, it could lead to problems/system hangs. You could use a cheap USB 2 drive to temporarily install and run OSX to see if it will be an actual problem or not.

If you have to remove the failed drive in the computer anyway, I would go with an internal drive solution. I personally would spend the money for the OWC sensor, as the temp control software could have issues with future OSX updates.

If you test it and can get away without having to physically remove the failed drive, I think I would go for the external thunderbolt solution and not risk damage by opening up the iMac.

I would review OWC & YouTube videos on how to open and replace the hard drive on the iMac, it is not an easy process, and you need to make sure to keep the glass and LCD screen clear of any dust/fingerprints. It may be worth the price to pay someone else to install the drive/sensor, depending on your access to clean work areas & skill level needed.

 

Can you erase or format the drive? (I am not at my Mac so I can't remember the exact verbage used in the disk utility app.)

Obviously, if you may have any data on the drive (pictures without backup, etc) you need to recover DO NOT DO THIS, as it will make the situation worse.

Of course, just because the SMART status says it is ok, does not always mean the drive is ok.