11.7.2 File System Guidelines
The guidelines are device generic and not related specifically to the Image Creation and Programming. These guidelines are applicable also while programming via Uniflash or MCU host.
- The File System by itself requires 12KB (3 blocks)
- Each file as a minimum consume:
- One block (4KB) for file with no fail safe support
- Two blocks (8KB) for file with fail safe support (twice the original size)
- Two blocks (8KB) for file with fail safe support (twice the original size)
- The most demanding system file in terms of space is the ServicePack file
- It is possible to set the maximum size attribute provided upon file creation (the file system reserves space). In this case, the actual size of the file is irrelevant as file system occupies the allocated space.
- There is no fragmentation in the file system. It means that an existing file which is removed would leave a "hole" in memory. This "hole" may be reallocated by the file system if the new file can fit into it.
- Each file includes a header which enlarges the actual size of the file. The overhead is 440 bytes. If the file size is very close to a multiple of block (4KB), additional block may be allocated. For example, a file of actual size 4000 bytes would result in allocating 2 blocks as 4000+440 > 4096.