The EliteBook 840 has an SSD storage medium which is better than most medium processor core laptops that were released around the same time as it. Most portable PCs of this type and age 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.
An SSD storage medium is actually the best storage medium amongst all portable PCs of this age and spec.
An HDD storage medium is the worst storage medium amongst comparable types of notebook PC.
It may also be worth considering one of the alternative portable PCs that have an SSD storage media currently available including the Elitebook 1040 G2[pl_2951226_price], the Elitebook 1040 G2[pl_2951226_price], or the ProBook 650[pl_2863577_price] all from HP which is cheaper.
If the storage medium of this HP portable PC is too bad for you then you might also want to consider the Toshiba Tecra Z50[plb_2090365_price] (SSD).