The HP EliteBook 755 G2 has an SSD storage medium which is better than most similar spec laptops that were launched around the same time as it. Most many processor core portable PCs 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 laptop's storage medium (SSD) is actually the best storage medium amongst all many processor core portable PCs that have been on the market for more than two years.
An HDD storage medium is the worst storage medium across comparable types of laptop.