The HP EliteBook 840 has an SSD storage medium which is better than most comparable spec laptops that have been available for around the same time as it. Most medium processor core laptops that have been around 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 actually the best storage medium across all notebook PCs of this type and age.
The worst storage medium across similar types of notebook PC is HDD.
Other portable PCs that have an SSD storage media currently available that you might want to look at include the DELL XPS 13 which has better reviews.
If the storage medium of this HP laptop is not good enough for you then you might also want to look at the Lenovo T420s (SSD), or the HP EliteBook 820 (SSD).