Complex sentence: Linux originally used the Minix file system, but it has a number of limitations such as only supporting 14 character names and having a maximum partition size of 64 MB. To replace Minix, the extended file system (or ext) was developed.
Split into simpler sentences: Linux originally used the Minix file system, but it had a number of limitations. For example, the length of filenames was limited to 14 characters and the partition size was limited to 64 MB. To replace the Minix file system, the extended file system (or ext) was developed.