How to create a bootable clone of a MacOsX system using Disk Utility

MacOsX features a backup utility called Time Machine, performing automated backups according to the user’s preferences. 
Time Machine is very important to preserve your data but has two main downsides:

1. Time Machine backups aren't bootable. This means that you have to restore them first to the hard drive, which can be a lengthy process, and sometimes you need your HD immediately operational. This can be a real deal breaker in a corporate environment.
2. The software will only copy the items changed since the last backup and, if your external destination hard drive runs short of space, it will delete the older backups automatically. This way the backup utility will get rid of items that have already been deleted before, but it will not alert you to this, which means you may end up losing copies of files you need without knowing it.

For these reasons you may want to create a cloned copy of your system on a separate external hard drive, too. This is very important, especially in a corporate environment, to have a disaster recovery strategy capable of ensuring your activity can be easily and quickly resumed in case of hardware failures or data corruption. In fact, you can boot from your clone hard drive by pressing down the Alt (⌥) key (sometimes also called the Option key) at start up and selecting it from the available options (Fig. 1). There are commercial programs for hard disk cloning (the most recommended are Carbon Copy Cloner and Super Duper), but not everybody knows that it can also be done using the resources supplied by MacOsX itself. You will only need an external hard drive (different from the one used for Time Machine and larger in size than the used space of your source hard drive).

Fig.1 (Click to enlarge)

Procedure

To create an exact copy of a Mac computer you’re going to use the built-in tool Disk Utility by accessing it from Recovery Mode, because an operating system cannot be cloned while it's being used.  You'll need to plug in the external hard drive to use as a clone and press the CMD (⌘) and R key simultaneously (Fig. 2) at the Mac boot-up to access Recovery Mode.

Fig. 2

Fig. 3 (Click to enlarge)

After accessing the Recovery Mode (Fig. 3), select Disk Utility and click Continue. At this point you'll be shown an overview of the disks present in your system (Fig. 4).

Fig. 4 (Click to enlarge)

Select your system partition where your MacOsX is installed, which is usually the first one in the list; this will be your source hard drive. Then click Restore on the right and select your destination hard drive (the external hard drive to use as a clone). To do this, select the partition on the destination HD where you are going to copy the source operating system (the whole disk in case of one single partition or a specific partition if there are more than one) and drag it to the Destination box. Next, click Restore to start cloning the source HD.

Wrap-up 

Using Disk Utility you'll have a bootable, cloned copy of your operating system that can be helpful in solving unexpected boot problems or for restoring a fresh copy of your software when you can’t track down what's causing a specific issue.
This process isn't so automated as with commercial software I’ve mentioned above and requires a little more understanding of what you are doing, but it can lead to the same results by supplying you with a quick and helpful alternative solution in case of hard drive failure or data corruption. And it's free of charge, which doesn't hurt.

 Resources:

• iMac first steps for dummies -guide to MacOsX Mavericks part 2 
• Carbon Copy Cloner download page
• Super Duper download page

Happy New Year to my readers!