The ThinkPad X1 Carbon has an SSD storage medium which is better than most laptops of this age and spec. Most notebook PCs that have been on the market for a similar time to it have an HDD storage medium. 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 notebook PC's storage medium (SSD) is in fact the best storage medium across all similar spec laptops that were launched more than a year ago.
The worst storage medium amongst comparable types of notebook PC is HDD.
If you would prefer a portable PC with a better storage medium then you might want to consider the Elitebook 820 G2 (SSD), or the EliteBook 820 G2 ($729.99) (SSD) both from HP.