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There are few they are expensive, and in my testing they provide four to five times as much Read speed as SD cards did. USB 3 flash drives aren’t all that fast either unless you specifically get one that was designed for speed. 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. ![]() 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). 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. OS X EL CAPITAN BOOTABLE USB SOFTWAREI performed the speed tests for by blog using standard speed test software that is intended for testing hard drives and flash based storage devices. OS X EL CAPITAN BOOTABLE USB MACYes, 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). 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. For about one month after Yosemite was officially released, I did continue to use it for regular startup. 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. I thought this strange, because booting from a USB 2.0 external hard drive is typically slow by quite usable. They would boot, but user experience ranged from unusable to barely usable, not appropriate for testing (USB 3 is probably much better). I tried installing OS X on several sufficiently large USB 2.0 flash drives. Pure transfer rate performance matters less for running an OS. ![]() 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. 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. 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. Running an OS is more about reading data, not writing data (unless the task being performed at the moment is writing data). In my testing, reading data FROM the SD card is about three times faster. It is likely that you did your testing by writing a large amount of data TO the SD card. My Mac mini, which is actually not that new (released in 2011), has a high speed SD card slot.Īlso, there is a significant difference in speed between reading and writing. Therefore, the bottleneck may be the Mac’s interface, not the SDXC card. The “high-speed” SD card slots on more recent Macs are faster. SD card slots on older Macs are slower I believe they use the USB bus. Since I don’t use my SD card slot (on back of my Mac mini) for anything else, I just leave it in there. It becomes a super- “Recovery HD” for maintenance and emergency boot. OS X EL CAPITAN BOOTABLE USB INSTALLProvides accurate user experience for testing the beta.Īfter 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. Faster than booting from USB (2.0) or FireWire. Not as fast as an internal SSD, but on par with an internal hard drive. Run the OS X installer and select it as the target just like any volume. OS X EL CAPITAN BOOTABLE USB MAC OSUse Mac OS Extended (Journaled) as Format. Click Options button and select GUID Partition Table. OS X EL CAPITAN BOOTABLE USB FOR MACRe-initialize it for Mac using Partition tab in Disk Utility. 32GB gets a bit tight on space, if you want to test throughly. I’ve recently seen 64GB SDXC cards for about $30. 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. ![]()
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