this tera-bites —

Apple announces replacement program for 3TB hard drives in 2012 and 2013 iMacs

Program ends December 19, 2015 or 3 years from purchase date, whichever is longer.

If you bought a 27-inch 2012 iMac with a 3TB hard drive, check to see if your computer is affected by the replacement program.
Enlarge / If you bought a 27-inch 2012 iMac with a 3TB hard drive, check to see if your computer is affected by the replacement program.
Andrew Cunningham

Apple has just announced a replacement program for 3TB hard drives in 27-inch iMacs purchased between December of 2012 and September of 2013—approximately the lifespan of the 2012 iMac, though some of the first 2013 iMacs sold could potentially be affected as well. Apple says the drives "may fail under certain conditions."

Apple offers 3TB hard drives in its larger iMacs as an upgrade option, either as a standalone drive or as part of a Fusion Drive setup. Either way, enter your Mac's serial number on the replacement program page to check and see if you're eligible for a replacement. You'll want to back your data up before replacing the drive since you'll need to reinstall a fresh copy of OS X on the new drive when you get it.

The program ends on December 19, 2015 or three years from your iMac's purchase date, whichever comes last. If you've already paid to replace a 3TB drive and your Mac is affected by the problem, you can contact Apple to negotiate for a reimbursement.

Channel Ars Technica