On a freshly created and nearly empty filesystem, after extlinux --install creates ldlinux.c32 and ldlinux.sys, they're both fragmented: $ filefrag ldlinux.* ldlinux.c32: 3 extents found ldlinux.sys: 2 extents found extlinux could avoid this in several different ways, most easily by reserving enough space for the file up-front using ftruncate.