How to create a bootable OS X El Capitan USB flash drive

“If you have a spare USB flash drive laying around, you should consider putting it to good use by creating a bootable installation drive for the OS X El Capitan Beta,” Jeff Benjamin writes for iDownloadBlog.

“Creating a bootable drive has many benefits and uses. For starters, it makes it easy to install a fresh copy of whatever operating system you have configured on the drive,” Benjamin writes. “Secondly, it makes it easy to install an operating system on a separate partition, or on a virtual machine. Lastly, it’s just smart business to always have a quickly accessible and portable installation media laying around.”

Benjamin writes, “In this tutorial and video walkthrough, I’ll show you how to create a bootable USB drive for OS X El Capitan in just a few easy steps.”

Easy instructions in the full article here.


  1. who cares. they need to spend time fixing yosemite or call it dead and let’s move on. there are enough security flaws to make me start using windows july 29.

  2. USB is sort of, well, OK for traveling, maybe.

    I’ld much rather have a FireWire or Thunderbolt SSD so I can have several clones and an archive on a number of partitions for max flexibility on fixes.

    1. No, Thunderbolt sticks don’t exist. Or, if they do, they’re called SSDs.

      However, USB 3 small SSDs exist and that’s what I’d use instead of a thumb drive. They act like disks and are much faster. More expensive but having one around with a clean install of the latest system you’re using is a worthwhile investment.

    2. Thunderbolt sticks are not yet available (IIRC) but would be a fantastic idea because Thunderbolt is so many time faster than USB3 in the real world. Of course to get maximum speed you would have to arrange the flash memory like an SSD to be able to take advantage of Thunderbolt’s extraordinary speed. I would love to have one for my OS X Betas so I could install it so much faster. Intel did showcase a 128 GB Thunderbolt stick back in 2013 so it has been done, we just need to find someone who is selling (an affordable) one today.

  3. If your Mac has a high-speed SD card slot, like my Mac mini, a better solution is to use an SDXC card that is at least 32GB. I’ve recently seen 64GB SDXC cards for about $30. 32GB gets a bit tight on space, if you want to test throughly.

    Re-initialize it for Mac using Partition tab in Disk Utility. Set Partition Layout to 1 Partition. Click Options button and select GUID Partition Table. Use Mac OS Extended (Journaled) as Format. Name it as desired, and click Apply. Run the OS X installer and select it as the target just like any volume.

    It is surprisingly fast. Not as fast as an internal SSD, but on par with an internal hard drive. Faster than booting from USB (2.0) or FireWire. Provides accurate user experience for testing the beta.

    After beta testing is over, you can put a standard install on it, along with any third-party disk utilities (like TechTool Pro) you may have. It becomes a super- “Recovery HD” for maintenance and emergency boot. Since I don’t use my SD card slot (on back of my Mac mini) for anything else, I just leave it in there.

    1. Actually SDXC cards are built for capacity not speed, none of the ones I ever tested came close to the speed of my stock internal MacBook Pro hard drive (which delivers 80 to 100 Mbps depending on how you test it). The fastest I ever saw in my testing was 24 MBps which is certainly functional but is more in line with the speeds I measured for USB flash drives. Its still a good and convenient idea, its just not faster than a good flash drive and its a lot slower than the fastest flash drive (which can do 100 MBps).

      1. SD card slots on older Macs are slower; I believe they use the USB bus. The “high-speed” SD card slots on more recent Macs are faster. Therefore, the bottleneck may be the Mac’s interface, not the SDXC card. My Mac mini, which is actually not that new (released in 2011), has a high speed SD card slot.

        Also, there is a significant difference in speed between reading and writing. It is likely that you did your testing by writing a large amount of data TO the SD card. In my testing, reading data FROM the SD card is about three times faster. Running an OS is more about reading data, not writing data (unless the task being performed at the moment is writing data).

        In running an OS, solid state storage (whether it’s an SSD or SD card) also has an advantage in non-sequential data access speed, compared to a hard drive. Therefore, if you performed a speed test by writing data to a hard drive, it is likely to be mostly sequential, where the data is efficiently written to adjacent physical locations on the surface of the disk. Accessing data to run an OS is NOT sequential, and with solid state storage it does not matter whereas a hard drive is less efficient. Pure transfer rate performance matters less for running an OS.

        I tried installing OS X on several sufficiently large USB 2.0 flash drives. They would boot, but user experience ranged from unusable to barely usable, not appropriate for testing (USB 3 is probably much better). I thought this strange, because booting from a USB 2.0 external hard drive is typically slow by quite usable. However, my experience using an SDXC card in my Mac mini for Yosemite testing last year was so good that I considered using it as my regular startup disk indefinitely. For about one month after Yosemite was officially released, I did continue to use it for regular startup. But I soon installed an SSD in my Mac mini (and created a DIY Fusion Drive with the stock hard drive); that is obviously faster than using the SDXC card as the startup disk.

        1. Yes, older Macs have the SD card slot connected to the USB bus, newer ones (like mine) are connected to the PCI bus so the Mac interface is as fast as its PCI bus can go (which is many times faster than any SD or SDXC card can go). I performed the speed tests for by blog using standard speed test software that is intended for testing hard drives and flash based storage devices. It tests both read and write and yes, on thee flash devices the Read speeds are common two to five times faster than the Write times, this is normal and also happens on the most expensive SSDs. I found in my testing that SD or SDXC cards really weren’t all that fast (the fastest one tested topped out at 25 Mbps). When I spoke to one of the manufacturers they told me that its because SD and SDXC is intended for digital cameras and they do not have a huge speed demand so no effort is put into making the SD cards ant faster. USB 3 flash drives aren’t all that fast either unless you specifically get one that was designed for speed. There are few they are expensive, and in my testing they provide four to five times as much Read speed as SD cards did. The premium priced high performance USB 3 flash drives do work well for Beta versions of the OS, being as fast or a bit faster than my hard drives (just depend what we are comparing) but there are no where near as fast as a proper SSD (which I tested side by side with the USB 3 flash drives). If speed is not a concern and if you have SD or SDXC cards available, then by all means try them. If you need speed then get an external SSD. If the SSD is too expensive then get a premium USB 3 flash drive (but check before you buy, almost all the USB 3 flash drives I tested were barely able to get up to 20 MBps and some were just as slow as USB 2 flash drive so beware).

          1. Instead of using testing software (which is likely to produce biased results), you should do some “real-world” tests. Such benchmarking software is designed to test removable storage with data transfer in mind, which is what most people need tested. Most people do not need know how well an SDXC card works as a startup disk.

            For example, when I transferred 6GB of data FROM the SDXC card to the internal SSD, it took about 2 minutes. That’s around 50MB/sec, which is inline with the product’s description of “up to 70 MB/sec.”

            Also, try actually installing OS X on an SDXC card (32GB or larger) and running that system as your test. It works really well and runs smooth, based on my actual experience (not benchmarking results). I have a “real” SSD in my Mac mini now (and it is obviously superior), but my 64GB SDCX card (Sony brand) is great for the beta test system. It provides an accurate user experience, with plenty of space for installing and testing with third-party apps (including games), unlike using “a spare USB flash drive laying around,” which is what this tutorial describes.

            I don’t know what a “premium USB 3 flash drive” at 32GB or 64GB costs, but you now can get a “premium-brand” 64GB SDXC card described as “up to 90MB/sec” for about $30…


            (32GB version is less than $20)

            As I said in my original post, “If your Mac has a high-speed SD card slot… a better solution is to use an SDXC card that is at least 32GB.”

  4. Well that was a waste of time. I already know how to create a USB install drive. I thought this was going to allow me to run OS 10.11 from the USB, not give me an install disk to run installation files from. Useless.

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