What are the pros and cons of using an SD Card for data storage? They’re cheap, easy to use, and my Macs all have SD card slots. But is there a downside?

SD cards are a great storage option—after all, many of us have used them for a long while with cameras, MP3 players, and other electronics devices. But like anything else, there are tradeoffs.

First, let’s talk about the pros for using SD cards to store your data. Because SD cards are small and relatively inexpensive, you will be able to carry one around with you no matter where you go. Thanks to the card slots on late-model Macs, moving files around is quick and easy. Another plus for SD cards: magnets don’t affect them, unlike magnetic internal or external hard drives.

Just like all storage media, SD cards have flaws, too.

But before you invest in a truckload of the tiny cards, understand that they’re not perfect for every situation. Like all flash-memory devices, SD cards have a limited number of read and write cycles. So, you won’t want to store any files that need constant read/write access (think databases and stuff like that). With today’s flash devices, you’re looking at around 100,000 write cycles before errors begin to appear. Many of the modern SD cards implement a software feature called wear leveling that attempts to write to the card in a way that minimizes wear in only one area on the card.
 
Another problem with SD cards is that they can be slow. The fastest SD cards available today are Class 10 SD cards, which can write and read at 10 MB/s. Comparatively, a 5400-rpm magnetic hard drive can read and write at around 300 MB/s. The bottom line is that SD cards are best suited for storing and transporting data, rather than using them for working files.

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