MacBook Pros Can Boot From Media on SD Card Slots
According to Katie Marsal’s article in Apple Insider’s forums, Apple’s Non Retina Display MacBook Pros both the 13 inch and 15 inch have a SD (Secure Digital) card slot feature. The SD card slots on the MacBook Pros are primarily for reading and writing media files to SD cards, but in case of an emergency this slot can act as a lifesaver, allowing you to boot from an SD card if you are not able to boot it from the internal hard drive.
Secure Digital (SD) devices are used as storage media for mobile phones, cameras, digital audio players, car navigation systems and electronic books. To fall into this media category the SD devices must conform to SD standards for non-volatile memory cards.
Aligning with Apple’s usual innovative hardware design philosophy the MacBook Pros with the SD card slots can use these SD slots and media to install Mac OS X on an SD card. You can use the SD card as a startup volume by changing the formatting of the SD card from GUID to the Mac OS Extended file format through Disk Utility.
The MacBook Pros’ ability to boot from the SD card can be particularly useful if you ever run into problems with a MacBook Pro’s internal drive. Of course of your hard drive fails or starts to show early warning signs of failure, you will want to stop any extensive reading and writing from the hard drive or SSD and immediately back up your data to the best of your ability if it has not already been done.
Having a SD card with the Mac OS Extended format and Mac OS X on it can be incredibly useful, by allowing you to boot from the card and troubleshoot or rescue critical files from the problematic drive. It is also possible to run drive diagnostic and repair applications off the SD card boot volume but they function at a fraction of the usual speed.
Apple’s original purpose to move towards SD card slots on the MacBook Pros was to accommodate the rapid transfer of media, such as photos and video.
The MacBook Pros have a maximum speed of 240 Mbit/s for SD media through the SD card slot, which is much faster than the transfer rate of most SD media.
- Class 2 media has a maximum transfer rate of 4 Mbit/s
- Class 4 media has a maximum transfer rate of 4.8 Mbit/s
- Class 6 media has a maximum transfer rate of 45 Mbit/s
Any SD card that is the standard SD 1.x and 2.x is compatible to work in the slots. The MacBook Pros also accept SD cards that are Standard SD (4 MB to 4 GB) and SDHC (4 GB to 32 GB).
Cards Compatible in the MacBook Pro SD Slot:
- MultiMediaCards (MMC)
These cards must first be inserted into a “passive” adapter that makes the above cards conform to the width and thickness specifications for the laptop slot.
The standard SD card specification for a memory card is usually 32 mm by 24 mm by 2.1 mm. But Apple says the MacBook Pros can also use thinner cards, such as the MultiMediaCards. Cards thicker than 2.1mm or that has surfaces larger than 2.1mm should not be used, as you may damage the SD card slot if inserted into the laptop.
The MacBook Pros also accept cards that are larger than 32 GB.