The Lenovo X240 has a better storage medium than most laptops of this age and type. This notebook PC has an SSD storage media, whereas most portable PCs of this spec and age have an HDD storage media. Solid State Drives (SSD) store data in semiconductors on a circuit board rather than using magnetic or optical media. Solid State Drives have no moving parts which makes them very fast and reliable.
This portable PC's storage medium (SSD) is in fact the best storage medium across all portable PCs that have been available for a comparable time to the X240.
Across comparable types of portable PC the worst storage medium is HDD.