ext2 is still the filesystem of choice for flash-based storage media (such as SD cards, and USB flash drives), since its lack of a journal increases performance and minimizes the number of writes, and flash devices have a limited number of write cycles.
However, a keydrive or any other device may be formatted using another filesystem (for example HFS Plus on an Apple Macintosh, or Ext2 under Linux, or Unix File System under Solaris or BSD).
Stephen Tweedie first revealed that he was working on extending ext2 in Journaling the Linux ext2fs Filesystem in a 1998 paper, and later in a February 1999 kernel mailing list posting.
He is credited as one of the primary developers of the Extended file system (ext) and Second Extended file system (ext2) for Linux.