How to upgrade an OS X Lion system's hard drive

Replacing a hard drive on a Mac may sometimes be necessary to either upgrade to increase its capacity, replace a faulty drive, or upgrade your Mac with a faster solid-state drive (SSD), which will often breath new life into an older system. While swapping out an older hard drive for a newer one is generally fairly simple to do, in Lion the upgrade may take a few more steps.

There are several ways of migrating data to a new drive for your Mac, but generally it involves either cloning the system or restoring from a backup (either by migrating or performing a full restoration). In past versions of OS X, these two approaches resulted in the same final setup, but in Lion you need to take into consideration the system's recovery partition before performing the upgrade and migrating your data.

While cloning is fairly straightforward, this process can only properly copy one volume at a time and will overlook the recovery HD partition that Lion sets up for use with FileVault and OS X maintenance routines. Given that you can create a Lion installation drive, a separate recovery drive from any Lion-based Mac, or even use Apple's Internet-based recovery tools at any time in place of the local Recovery HD partition (2010 Macs and later), having this partition on the system is not necessary to run Lion. However, it may be a good option to keep around in case the other recovery approaches do not work, or to use advanced features like FileVault.

If you do wish to keep the recovery partition on your system, then when you install your new hard drive you will first have to install a fresh copy of OS X to create the recovery partition, followed by restoring your files and data to the boot volume. This can be done with the following steps:

1. Create a backup of your system
   Use Time Machine or a cloning tool to create a full system backup of your boot drive that can be either booted from directly or used to fully restore your boot drive to a bootable state. In addition to creating a backup of your boot drive, use Apple's recovery partition toolto create a USB recovery drive or create an OS X Lion installation drive (this will speed the installation process later on).
2. Swap out your hard drive
   Follow either Apple's instructions or those from a reputable source like iFixIt to open your system and swap out your older drive for the new one.
3. Boot to the OS X recovery partition or the Internet recovery
   If your system was made in 2010, then you likely have the option to use Apple's Internet-recovery tools to reinstall OS X, or you can attach your previously made USB recovery or installation drive and use that to restore OS X.
4. Install OS X to the new hard drive
   Once booted to the OS X recovery tools, use the Install OS X option to reinstall the operating system. If you previously created a full OS X installation drive, then this process will go fairly quickly, but otherwise you will have to log into Apple's store and download the Lion install files, which can take several hours to complete.

At this point you have restored the recovery HD partition on the computer and now have two options to restore your data:

• Migrate from backup
  If you boot to the OS X installer, the system will initially prompt you to migrate from a previous system, which you can do with your previously made clone or Time Machine backup. This step should get all of your data onto the new drive, but because migration is yet another manipulation of your data setup, some people might be skeptical of its thoroughness.
• Restore from backup
  If you would like to avoid using the OS X migration assistant for transferring your files from backup, you can instead restore from your backup. To do this, you have two options based on the type of backup you have. If you have a Time Machine backup, restart your system and hold Command-R to boot to the newly created recovery partition. Then choose the option to restore from backup, select your most recent backup from the Time Machine disk, and then click restore to copy its contents back to your boot drive.
  
  If you have a system clone, then reboot with the Option key held down and you should see your Mac's boot menu show up. Select the clone drive and boot off of it, and when logged in use your cloning tool to mirror the active boot drive (your older hard drive) to the new internal drive. When finished with either this or the restoration from a Time Machine backup, restart your computer and you should be up and running on your new hard drive.

(courtesy:cnet.com)