Errors when writing NanoBSD images to CF
If an error is received when writing a Compact Flash card with a NanoBSD image, there could be several reasons why it didn't work properly.
Some of these errors stem from the fact that, over time, manufacturers have slowly reduced the size of Compact Flash media to the point that in some cases the images are now larger than the cards, or the same size.
Same Image Size
If the CF size is exactly the same as the NanoBSD image size, it may give an error but work properly. The last few sectors of some cards are reserved for remapping or, per their specs, not available for user data storage.
Image too Large
If the image is too large, an errors will be encountered when writing that may not be obvious when trying to use the cards. The shared config slice is at the end of the card, and it does not usually contain much data (the config file, some config backups, compressed backups of the RRD files and DHCP leases), but should it become full enough to go past the end of the image, it may have issues.
If errors are received randomly when writing the card, or at a certain spot well below the card's actual size, there may be a problem with the CF media itself. Try another CF card if possible, or another CF reader. The blocksize or other write parameters may also need adjusted if using a utility that supports such options (like dd)