The latest version of OS X, 10.11 El Capitan, has been out for a while now. Long enough to consider the new version of OS X stable [1, 2]. I decided that this time instead of doing a system upgrade I would take the extra time to do a clean install.
Upon Which Macs Can OS X 10.11 be installed?
In general, if you are running OS X 10.10 Yosemite or OS X 10.9 Mavericks now, you will be able to run OS X 10.11 El Capitan. The hardware requirement for El Capitan is a Mac with a 64-bit CPU (Intel Core 2 Duo or newer). Not sure what you have? Click Apple Menu >> About This Mac to see which system you have. The detailed list:
- iMac (mid-2007 or newer)
- MacBook (13-inch aluminum late 2008 or 13-inch early 2009, or newer)
- MacBook Pro (13-inch mid-2009, 15-inch mid/late 2007, 17-inch late 2007 or newer)
- MacBook Air (late 2008 or newer)
- Mac mini (early 2009 or newer)
- Mac Pro (early 2008 or newer)
- Xserve (early 2009)
So why do I want to upgrade?
Most important are new security features and patches that are introduced in OS X 10.11. There are also several new features that I want to take advantage of and core pieces of the operating system have been optimized to provide the user with better performance [1-3]. Most reports I have read, and users I have talked to who have updated to El Capitan, say this release is an improvement .
There have been a few who have been very critical of El Capitan [10, 16-18]. Solutions or work arounds for several of these problems have been suggested [22, 23]. Among the criticisms that have been reported:
- slow operation
- problems with Microsoft Office
- printing problems
- problems with iTunes
- Wi-Fi issues 
- problems with AirDrop
Clean Install vs. Upgrade?
I bought my Mac Mini back in 2011 and have performed an upgrade each time a new version of OS X has come out. I thought it was about time to do a clean install and get rid of the clutter that has accumulated over the past four years. Of course taking this route will require more time and effort than simply doing an upgrade.
The Process I Went Through to Upgrade
The process I followed when I upgraded to El Capitan is as follows:
- 8GB or larger USB Thumb Drive – NOTE any existing data on this drive will be lost
- About 5-6 hours of free time
- Download and install DiskMakerX- DiskMaker X is a little free utility that allows you to make a bootable USB drive from the OS X Installer downloaded from Apple [20, 21].
- Apply all updates – Open the App Store and click on the “Updates” tab. If you have any available updates install them.
- Download the El Capitan Installer – I went to the App Store and downloaded the OS X 10.11 El Capitan Installer (You can find it here).This file is over 6GB so it will take a while to download (about an hour when I did it). When the download completes, the Installer automatically loads and presents you with a screen prompting you to click on “Continue” to begin the Upgrade installation. A this point Quit the Installer. This will leave the Installer file in your Applications folder. Open Finder >> Go >> Applications and drag the Installer file to a new location, such as your desktop. Hold down the Option key as you drag the Install OS X El Capitan App from your Applications folder. If you don’t hold down Option, you’ll create an alias, not a copy.
- Make Bootable USB Drive with Installer – I inserted an 8GB Thumb Drive into one of the systems USB ports. I then ran DiskMaker X and when prompted, I chose the OS X 10.11 El Capitan Installer I had copied to my Desktop as the input. When prompted for the output device, I selected the 8GB Thumb Drive I had just added to the system [13, 24]. The process of making this bootable USB drive took about an hour to complete.
- Backup – I strongly recommend that before you make any changes to your system that you make a backup! In fact, you should be running a Time Machine backup at least weekly. I also suggest cloning your boot drive. This will make recovery much easier if you have to revert to the original system. I use my NewerTech dock to mount a 3TB SATA disk partitioned into a 60GB boot volume (‘System’) and a 2.94TB Time Machine volume. I used Carbon Copy Cloner to ‘clone’ (with SafetyNet off) my 60GB SSD boot drive to ‘System’ volume, then let Time Machine run to bring my backup current. I then rebooted my Mac to insure that the cloned disk was bootable (I chose the new clone as the boot device by going to Apple Menu >> Restart then held Option key down when I heard the tone during the reboot). I selected ‘System’ as the boot disk. Once the Mac had finished booting I made a few tests to verify that I had a good backup.
- I rebooted my system again, selecting the internal SSD as the boot drive. This returned my system to its original state.
- I wanted to install El Capitan on an external drive so that I could test before making the final commitment to to the new version of OS X. I replaced the 3TB disk in my NewerTech dock with an 80GB SATA drive. I reformatted the 80GB drive (Finder >> Go >> Utilities >> Disk Utilities then selected the 80GB drive and partitioned it as OS X Extended (Journaled), naming ithe volume ‘System2’.
- Upgrading my system
- I rebooted my system again, this time selecting the USB Installer as the boot device. This allowed me to perform a clean install of OS X 10.11 on the 80GB drive .
- I chose to Install OS X, then chose the target drive as the 80GB ‘System2’ volume. The clean install began and ran, with a few reboots, for about 75 minutes. At that point I went through the new system setup.
- The system was finally ready for use about 30 minutes later. Now this is a virgin OS X installation with no user data and no applications installed other than those that come with OS X. I still had work to do.
- Post Upgrade Completion
- Now that the system was at OS X 10.11, I wanted to add my user files and the applications I had installed previously. Fortunately, Apple has a built in utility that handles this – Migration Assistant. Using Migration Assistant I pulled the data I wanted from the old boot drive over to System2 [9, 11, 19].
- With this done I was operating from the System2 drive under OS X 10.11 with all of my user data and applications in place.
- I remained running from the System2 drive for a couple of days, but soon decided I was satisfied enough with the update to commit to OS X 10.11. I used Carbon Copy Cloner to ‘clone’ the System2 drive back to my internal SSD. I rebooted selecting the SSD as the boot device and I am now happily
running OS X 10.11 from my SSD.
Was the Clean Install Worth the Time and Trouble?
While I would not do this every time a new version of OS X is released, I think the answer is ‘YES’. I compared the old boot drive to the new boot drive and the new drive had about 2GB more free space (38.26 GB used on original boot drive vs. 36.26 on the System2 drive).
Was Upgrading to El Capitan Worth it?
For me the overwhelming answer is ‘YES’. I have been running under El Capitan now for four days and I have encountered no problems. While that is a relatively short period, I am feeing comfortable with OS X 10.11. I have also found some of the new features in El Capitan very useful.
I wanted to recognize Michael Sidoric from CapMac for his many suggestions to the clean install process.
 OS X El Capitan is here: Quick instructions on how to update your Mac
 OS X El Capitan: Download and Installation Quick Guide
 OS X El Capitan is Here! Upgrade For A Smoother Mac Experience
 How to install OS X El Capitan
 OS X El Capitan Available to Download Now for All Mac Users
 How to upgrade to OS X El Capitan
 Is Your System Ready for El Capitan? OWC Helps You Make Sure
 How to See All the Software Disabled by OS X El Capitan
 Setting Up a New Mac: Should You Migrate or Do a Clean Installation?
 ‘El Crapitan’: The biggest problems plaguing early OS X upgraders
 Mac OS X – How to use Migration Assistant to transfer files from another Mac
 Fixing Wi-Fi Issues in OS X El Capitan
 How to Create a Bootable El Capitan USB Install Drive with DiskMaker X
 How to Clean Install OS X El Capitan on a Mac
 The Complete Guide to an OS X Clean Install of El Capitan
 OS X El Capitan: Worst OS Release Yet
 OS X El Capitan: Image Capture Now Hangs Sometimes
 OS X El Capitan Breaks Time Machine
 Move your content to a new Mac – Apple Support
 How to Create a Bootable El Capitan USB Install Drive with DiskMaker X
 How to make your own bootable OS X 10.11 El Capitan USB install drive
 The Most Common OS X El Capitan Problems and Solutions
 10 Common OS X El Capitan Problems & How to Fix Them
 How to Install Mac OS X Using A Removable USB Drive
See my other OS X articles