Do more with your Apple gear
Anyone can sign up for the OS X public beta and take El Capitan for a spin
“Get started with El Capitan today to help app developers make your vital apps and kit work with the final version”
There are several reasons you might want to make an external boot disk for El Capitan. If you’ve signed up to the public beta program, for example, creating an external boot disk is the safest way to try out Apple’s new operating system while retaining the ability to instantly fall back to Yosemite when you need to do some work.
Prior to the new OS launching, it may also be a good idea to do the reverse – create a boot disk for Yosemite before you update to El Capitan. That way, if anything goes wrong, or if you find that El Capitan causes problems with apps or hardware you need, you can easily boot back into Yosemite.
The processes for each of those tasks are different, however. The El Capitan boot disk will hold a clean install of the new system, or a beta of it, and nothing else. If you were to do that for your current OS and something went wrong with El Capitan after upgrading, you might have to start over, reinstalling everything, losing files that weren’t backed up. At best, you’d endure a lengthy restore from Time Machine.
So, it’s much better to clone your current system and use that as a backup when you install El Capitan. You should do that anyway, as a matter of course, whenever you update the operating system or make any major changes to your Mac.
There are a number of ways you can clone your boot drive, and Carbon Copy Cloner (bombich.com) offers a whole raft of options for creating clones, including the ability to create specific tasks and schedule them. It also provides a simplified version of its interface, designed to allow you to easily clone one drive to another. The best news of all is that there’s a free, full‑featured 30-day trial you can take for a test drive and use to clone your system before installing a new version.
In the rest of this tutorial, we’ll show you how to create a boot disk for the
Clone your current boot drive and use that as a backup when you install El Capitan
El Capitan public beta. The process is similar if you want to create a clean, system-only boot volume of any version of OS X since Lion (assuming you’ve had an Apple ID since the launch of the Mac App Store and have previously downloaded each version of the OS).
You can access any OS X installer from Lion to Yosemite, if you have previously downloaded them, from the Purchased tab in the Mac App Store. Just click on the tab and scroll through the list of apps until you see ‘OS X’ and then the name of the version you want. When you find it, click Download. This will put an installer for that version into your Applications folder, ready for you to install on any disk.
Choosing a disk
The first part of creating a bootable install disk for any OS is to decide where you’re going to install it. An external SSD would be perfect, since it’s fast and will have plenty of space on the disk. For El Capitan, you’ll need a minimum of 16GB, so you could use a USB stick if you wanted to. That’s fine for storing just the OS, and makes for a neat solution as an emergency boot disk. But if you want to test drive apps with the El Capitan beta, you’ll quickly run out of room on a USB stick (and it’ll be relatively slow). So, if you don’t have an external SSD, and don’t want to buy one, the next best option is a Thunderbolt or USB 3.0 hard drive, if your Mac has a suitable port. If not, a USB 2.0 drive will do the job, though again it will be slower than the other external options.
Preparation
Plug in the drive you plan to use and wait until it mounts. If you haven’t already signed up to the El Capitan beta program, go to http://beta.apple. com and follow the instructions to sign up. You’ll need an Apple ID. If you’ve already signed up, you’ll need to go to http://beta.apple.com to sign in and nominate a device to verify your
identity, then type in the code that Apple sends you to complete the twostep verification process.
Once you’ve logged in, you’ll be taken to the ‘Guide for Public Betas’ page. Scroll down it to Getting Started and click ‘Enroll your Mac’. On the next page, scroll down to step 2 and click the button labelled ‘Download the El Capitan public beta’. The link will take you to the Mac App Store, automatically enter your redemption code, and start downloading the El Capitan beta. Don’t click it yet; once it downloads, it will install automatically. Instead, when you’re ready, go to the step-by-step walkthrough below.
Other options
Installing the El Capitan beta on an external drive is only one option. Apple’s advice is to install it on a secondary Mac. If you have a second Mac and don’t use it for critical work, that’s a good option, provided you back up its hard drive first.
You could also partition your Mac’s main internal drive, and run a dual-boot system, choosing which OS to boot into either from System Preferences or by holding down the å key at startup. But to do that, you’d need to wipe your entire hard drive and reinstall Yosemite, as well as all your apps. That’s not necessarily a bad thing: you’ll have a brand new, fresh install of Yosemite at the end of it, without all the detritus that can build up and cause problems as you install one system on top of another and try out apps. However, it is also consuming and fiddly, and only an option if you have plenty of time to spare for reinstalling things.
The final option is to run El Capitan as a virtual OS (within your existing system) using Parallels Desktop or VMWare Fusion. That’s a bit more fiddly to set up, however, as it has to be installed from within the virtualisation software. It does allow you, however, to run El Capitan without restarting your Mac.
Is it safe?
El Capitan is beta software, which means it’s at a stage where its not yet considered fit for broad public release. It’s likely to have bugs which are yet to be ironed out. Whether these bugs are minor irritations or potentially big problems is anyone’s guess. But at this stage – El Capitan has been tested by
developers since early June and by Mac users at large since early July – it’s unlikely to be the latter.
Nevertheless, you should treat it with caution. That means backing up all your data, preferably using a Time Machine or other incremental back-up system, as well as cloning your hard drive. Don’t use it for mission critical work at this stage, and don’t store any data on your El Capitan disk without also creating a copy somewhere else.
However, as long as you take those precautions, there’s nothing to fear. Thousands of Mac users are already using it, and so far there have been no reports of serious problems with it. At this stage, the beta is reasonably close to the final version, but is likely to be updated again before the final release ships. So, the other thing you should do is keep the beta updated by allowing the Mac App Store to install updates as they become available.
What should I do when El Capitan ships?
Keep the disk that contains the beta version for a while. If you update your Mac to El Capitan and find you have problems with, say, Mail, comparing your main installation with the clean beta on the external drive may allow you to identify whether the problem is with El Capitan or with the main install of the final system on your Mac. If it’s the latter, you might be able to fix it by repairing permissions, rooting out troublesome preference files, or, as a last resort, by performing a full clean install of El Capitan on your Mac. Kenny Hemphill
The first part of creating a bootable install disk for any OS is to decide where you’ll install it