Mac OS X Lion and Creating a new Rascal ext3 microSD card

Using this technique it is possible to insert the Rascal ext3 microSD card in the Mac card reader and have it appear on the Mac desktop. According to the README for FUSE-EXT2 it is possible to write to the card but the document states “Although write support is available (and it is pretty stable) please do not mount your filesystems with write support unless you do not have anything to lose”. In any case, as far as I know, it is not possible for Mac OS X to format an SD card as ext3 so I chose not to take the risk.

I have VMWare Fusion installed so it was relatively easy to create a virtual machine running Ubuntu 10.04. Make sure you install VMWare Tools which optimises connectivity between Mac OS X Lion and the virtual machine. Once Ubuntu is running and assuming you have already installed OSXFUSE and FUSE-EXT2, you can do the following:

  1. Insert the Rascal microSD card into the Mac card reader. The “rascal-beta” card should appear on the Mac desktop
  2. In VMWare Fusion choose the Virtual Machine menu, then in the submenu USB & Bluetooth choose “Connect rascal-beta (Apple Internal Memory Card Reader)”. The “rascal-beta” card should disappear from the Mac desktop and in a few moments appear on the Ubuntu desktop
  3. In Ubuntu 10.04 it will have been mounted as /media/rascal-beta. You can then follow Brandon’s recipe for archiving the existing card filesystem.
  4. Having made a copy, you can right-click the mounted SD card in Ubuntu and choose Safely Remove Card. The card will disappear from the Ubuntu desktop but the card reader is still connected to the Ubuntu VM. Then from VMWare Fusion: Virtual Machine: USB & Bluetooth choose “Disconnect rascal-beta (Apple Internal Memory Card Reader)” and the SD card should reappear on the Mac desktop.

I repeated this with a new card, formatting it as ext3 according to Brandon’s recipe and then extracting the saved archive onto it. I’m running my Rascal off this copy.

While repeating these steps before writing this post, after ejecting the card safely from Ubuntu it entered the dreaded state on the Mac “The disk you inserted was not readable by this computer.” with the options Ignore and Eject. I tried everything – multiple restarts of the Mac and Ubuntu, uninstalling and reinstalling FUSE-EXT2 and OSX-FUSE etc. After an hour I concluded that the card must have been corrupted and was about to wipe it in Apple Disk Utility when I noticed it was read only. I had accidentally locked the card when pulling it out of the reader.

Apart from this, the above procedure seems reasonably robust. I did try some experiments without installing OSXFUSE and FUSE-EXT2 on the Mac. If you choose Ignore in the initial card insertion dialogue, it is possible to connect the card reader to the Ubuntu virtual machine and get it to recognise the card. However this seems to be a matter of luck and often requires multiple restarts.

First posted in the Rascal hardware and software forum.

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