14 DAY TRIAL // A support document posted this week by Apple says that Macs can mistakenly erase the content of an SD card if swapped with a similar model at the wrong moment.
The document in question is titled “Mac computers: Don't change SD cards while computer sleeps.” In it, Apple states, “Don't swap an SD card with another one of the same manufacture and capacity while your computer is sleeping. This could potentially lead to data loss.”
KB article HT6210 is terse, providing no additional information on the matter. But it bears just enough information to allow users to draw a very simple conclusion. The key issue lies in the “same manufacture and capacity” thing. A conflict occurs between the data it recorded prior to going to sleep and the data that it woke up to. The two conflicting sets of data have the potential to cancel each other.
To avoid this, “Always wake your computer and eject the SD card before removing it from your Mac,” Apple says.
The Cupertino company doesn’t say if this also happens with USB Flash drives, but it’s reasonable to assume that the same thing applies to these storage mediums as well.
Apple has also posted a KB article about Mac Pros showing a "Boot Configuration" alert when installing Windows 8. Check that out as well if you’re planning to dual boot OS X and Windows on your expensive workstation.