The HP ZBook has an SSD storage medium which is better than the HDD storage medium found on most portable PCs of a comparable age and spec to it. 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 amongst all similar spec portable PCs that are a comparable age to the ZBook.
Amongst similar types of notebook PC the worst storage medium is HDD.
We compared all the other laptops that have an SSD storage media to this notebook PC and we think the ZBook 17, and the ZBook 17 both from HP which has better reviews; or the DELL XPS 15 9530 which is cheaper are also worth considering.
If the storage medium of this portable PC is too bad for you then you might want to consider the HP ZBook 15 (SSD).