Limited disk space
Filesystems and partitions holding user data should be maintained with a maximum amount of free space to accommodate user activity. When considering the physical amount of disk space available, the system administrator may be forced to make a trade-off between the number of partitions in use and the availability of free disk space. Finding the right configuration depends on system requirements and available filesystem resources.
When disk space is limited, you may opt to reduce the number of partitions, thereby combining free space into a single contiguous pool. For example, installing Linux on a PC with only 1 GB of available disk space might best be implemented using only a few partitions:
50 MB. A small /boot filesystem in the first partition ensures that all kernels are below the 1024-cylinder limit for older kernels and BIOS.
850 MB. A large root partition holds everything on the system that’s not in /boot.